Di ec Measu emen s o
Polyelec oly e B ush Responses using
A omic Fo ce and Op ical Mic oscopy
Disse a ion
Von de Uni e si ä Bay eu h
zu E langung des akademischen G ades eines
Dok o s de Na u wissenscha en (D . e . na .)
genehmig e Abhandlung
Fakul ä ü Biologie, Chemie und Geowissenscha en
Leh s uhl Physikalische Chemie II
on
Johann E a h
Diplom-Physike
gebo en in Wasse los, Alzenau
E s gu ach e : P o . D . And eas Fe y
Zwei gu ach e : P o . D . Geo g Papas a ou
Disse a ion einge eich : 02.07.2013
Wissenscha liches Kolloquium: 11.11.2013
I
Die o liegende A bei wu de in de Zei on Juli 2009 bis Juli 2013 am Leh s uhl
Physikalische Chemie II un e de Be euung on P o . D . And eas Fe y an de Uni-
e si ä Bay eu h ange e ig .
Volls ändige Abd uck de on de Fakul ä ü Biologie, Chemie und Geowissenscha en
de Uni e si ä Bay eu h genehmig en Disse a ion zu E langung des akademischen
G ades eines Dok o s de Na u wissenscha en (D . e . na .).
Disse a ion einge eich : 02.07.2013
Zulassung du ch die P ü ungskommission: 10.07.2013
Wissenscha liches Kolloquium: 11.11.2013
Am ie ende Dekan: P o . D . Rhe Kempe
P ü ungsausschuss:
P o . D . And eas Fe y (E s gu ach e )
P o . D . Geo g Papas a ou (Zwei gu ach e )
P o . D . Jose B eu (Vo si z)
P o . D . And eas G eine
Con en s
Lis o Publica ions 1
1 O e iew 3
1.1 Ou line.................................... 5
1.2 Con en o he Indi idual Chap e s . . . . . . . . . . . . . . . . . . . . 5
1.3 Indi idual Con ibu ions . . . . . . . . . . . . . . . . . . . . . . . . . . 21
1.4 Re e ences.................................. 24
2 Theo y and S a us o he Field 25
2.1 In oduc ion................................. 27
2.2 F om Polyme s o Polyelec oly e B ushes . . . . . . . . . . . . . . . . 28
2.2.1 Neu alPolyme s.......................... 29
2.2.2 Polyelec oly es . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
2.2.3 Sel Assembly o Polyelec oly es . . . . . . . . . . . . . . . . . 38
2.2.4 Func ionaliza ion o Su aces wi h Polyelec oly es . . . . . . . . 41
2.2.5 Polyme B ushes .......................... 42
2.3 Su ace and In e acial Fo ces . . . . . . . . . . . . . . . . . . . . . . . 54
2.3.1 The De jaguin App oxima ion . . . . . . . . . . . . . . . . . . . 55
2.3.2 Van de Waals In e ac ions . . . . . . . . . . . . . . . . . . . . . 56
2.3.3 In e ac ions o Cha ged Sys ems . . . . . . . . . . . . . . . . . . 57
2.3.4 Capilla y In e ac ions . . . . . . . . . . . . . . . . . . . . . . . . 58
2.3.5 S e ic In e ac ions . . . . . . . . . . . . . . . . . . . . . . . . . 60
2.3.6 Con ac Mechanics . . . . . . . . . . . . . . . . . . . . . . . . . 63
2.4 Expe imen al Me hods: A omic Fo ce and Op ical Mic oscopy . . . . . 69
III

CONTENTS IV
2.4.1 A omic Fo ce Mic oscopy (AFM) . . . . . . . . . . . . . . . . . 69
2.4.2 Op ical Techniques . . . . . . . . . . . . . . . . . . . . . . . . . 76
2.5 Re e ences.................................. 81
3 So Colloidal P obe AFM 95
3.1 In oduc ion................................. 97
3.2 Expe imen al ................................ 99
3.3 Resul s and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
3.4 Conclusion and Ou look . . . . . . . . . . . . . . . . . . . . . . . . . . 107
3.5 Re e ences.................................. 109
3.A Suppo ing In o ma ion . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
4 Mechano esponsi e Polyelec oly e B ushes 119
4.1 In oduc ion................................. 121
4.2 Expe imen al ................................ 121
4.3 Resul s and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
4.4 Conclusion and Ou look . . . . . . . . . . . . . . . . . . . . . . . . . . 126
4.5 Re e ences.................................. 128
4.A Suppo ing In o ma ion . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
5 Pho o unable Su ace In e ac ions 145
5.1 In oduc ion................................. 147
5.2 Expe imen al ................................ 149
5.3 Resul s and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
5.4 Conclusion and Ou look . . . . . . . . . . . . . . . . . . . . . . . . . . 156
5.5 Re e ences.................................. 159
5.A Suppo ing In o ma ion . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
6 In e ac ions o Sphe ical Polyelec oly e B ushes 167
6.1 In oduc ion................................. 169
6.2 Expe imen al ................................ 171
6.3 Resul s and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
6.4 Conclusions and Ou look . . . . . . . . . . . . . . . . . . . . . . . . . . 182
6.5 Re e ences.................................. 186
CONTENTS V
7 Swelling Beha io o Block Copolyme Micelles 193
7.1 In oduc ion................................. 195
7.2 Expe imen al ................................ 197
7.3 Resul s and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . 199
7.4 Conclusion and Ou look . . . . . . . . . . . . . . . . . . . . . . . . . . 211
7.5 Re e ences.................................. 213
7.A Suppo ing In o ma ion . . . . . . . . . . . . . . . . . . . . . . . . . . . 220
8 Fu he Pe spec i es 223
8.1 Di ec Measu emen s o Con ac S esses o So Ma e ials . . . . . . . 225
8.2 Con ac and Adhesion o Biomime ic Pa e ned Adhesi es . . . . . . . 227
8.3 Tuning he Response o Mechano esponsi e B ushes . . . . . . . . . . . 239
8.3.1 Unde s anding o he Mechano esponse . . . . . . . . . . . . . . 240
8.3.2 Change o he De ec ion Scheme . . . . . . . . . . . . . . . . . . 244
8.4 Re e ences.................................. 248
9 Summa y 251
10 Zusammen assung 257
A Theo y o Polyme B ushes 265
A.1 Re e ences.................................. 270
B A Li le Coding wi h Igo 271
Danke 273
Lis o Figu es
1.1 The so colloidal p obe echnique . . . . . . . . . . . . . . . . . . . . . 8
1.2 Mechano esponsi e su aces . . . . . . . . . . . . . . . . . . . . . . . . 11
1.3 Pho o unable su ace in e ac ions . . . . . . . . . . . . . . . . . . . . . 14
1.4 In e ac ions o Sphe ical Polyelec oly e B ushes . . . . . . . . . . . . . 16
1.5 Swelling o Block Copolyme Micelles . . . . . . . . . . . . . . . . . . . 18
2.1 Responsi esys ems............................. 27
2.2 Polyme sys ems .............................. 29
2.3 Po en ialo aPE.............................. 35
2.4 Adso p ion o polyelec oly es . . . . . . . . . . . . . . . . . . . . . . . 39
2.5 Sel assembly o polyelec oly es . . . . . . . . . . . . . . . . . . . . . . 40
2.6 Func ionaliza ion o su aces wi h polyelec oly es . . . . . . . . . . . . 43
2.7 Di e en ypes o polyme b ushes . . . . . . . . . . . . . . . . . . . . . 44
2.8 P epa a ion o polyme b ushes . . . . . . . . . . . . . . . . . . . . . . 46
2.9 G a ed polyme chains . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
2.10 Pa ame e o a ca ionic polyme b ush . . . . . . . . . . . . . . . . . . 48
2.11 B ush p ope ies as a unc ion o sal concen a ion . . . . . . . . . . . 52
2.12 Phase diag am o polyme b ushes . . . . . . . . . . . . . . . . . . . . . 53
2.13 The De jaguin app oxima ion . . . . . . . . . . . . . . . . . . . . . . . 55
2.14 In e ac ions o cha ged Su aces . . . . . . . . . . . . . . . . . . . . . . 59
2.15 In e ac ions o polyme b ushes . . . . . . . . . . . . . . . . . . . . . . 62
2.16Con ac pa ame e s............................. 64
2.17 Con ac mechanics o elas ic bodies . . . . . . . . . . . . . . . . . . . . 67
2.18 A ailabili y o con ac mechanic models . . . . . . . . . . . . . . . . . . 68
VII
ABBREVIATIONS AND SYMBOLS XIV
IIonic s eng h
aKuhn leng h
MMolecula weigh
NNumbe o monome es
NA Nume ical ape u e
Pe mi i i y
LpPe sis ence len h
νPoisson a io
UPo en ial
PP essu e
RRadius, educed adius
KReduced modulus
nRe ac i e index
es Resonance equency
kSp ing cons an
iS ain in i di ec ion
σiS ess in i di ec ion
σSSu ace cha ge densi y
µTTabo pa ame e
TTempe a u e
wWo k o adhesion
EYoung’s modulus

Lis o Publica ions
1. Cha ac e iza ion o Adhesion Phenomena and Con ac o Su aces by So Col-
loidal P obe AFM.
E a h, J., Schmid , S., and Fe y, A., So Ma e , 2010. 6(7): p. 1432-1437.
2. Di ec Co ela ion be ween Local P essu e and Fluo escence Ou pu in Mechano e-
sponsi e Polyelec oly e B ushes.
Bunsow, J., E a h, J., Biesheu el, P. M., Fe y, A., Huck, W. T. S., Angewand e
Chemie-In e na ional Edi ion, 2011. 50(41): p. 9629-9632.
3. Sensi i e as Human Skin: Polyme Su aces wi h High P ecision P essu e De ec-
ion.
Fe y, A. and E a h, J., In e na ional Jou nal o Ma e ials Resea ch, 2011.
102(12): p. 1524-1525.
4. Tuning o he Elas ic Modulus o Polyelec oly e Mul ilaye Films buil up om
Polyanions Mix u e.
T enkenschuh, K., E a h, J., Kuzne so , V., Gensel, J., Boulmedais, F., Schaa ,
P., Papas a ou, G., Fe y, A., Mac omolecules, 2011. 44(22): p. 8954-8961.
5. Adso p ion o Sphe ical Polyelec oly e B ushes: om In e ac ions o Su ace
Pa e ning.
Hanske, C., E a h, J., Kueh , C. , T ebbin, M., Schneide , C., Wi emann, A.,
Fe y, A., Zei sch i Fü Physikalische Chemie - In e na ional Jou nal o Resea ch
in Physical Chemis y and Chemical Physics, 2012. 226(7-8): p. 569-584.
6. Re e sible Swelling T ansi ions in S imuli-Responsi e Laye -by-Laye Films con-
aining Block Copolyme Micelles.
Gensel, J., Dewald, I., E a h, J.,Be hausen, E., Muelle , A. H. E., Fe y, A.,
Chemical Science, 2013. 4(1): p. 325-334.
1
LIST OF PUBLICATIONS 2
7. Clay-Based Nanocomposi e Coa ing o Flexible Op oelec onics Applying Com-
me cial Polyme s.
Kunz, D.A., Schmid, J., Feich , P., E a h, J., Fe y, A., B eu J., ACS Nano,
2013. 7(5): p. 4275-80.
8. In-plane Modulus o Singula 2:1-Clay Lamellae Applying a Simple W inkling
Technique.
Kunz, D., E a h, J., Kluge, D., Thu n, H.; Pu z, B.; Fe y, A., B eu, J., ACS
Applied Ma e ials and In e aces, 2013. 5: p. 5851-5855
9. Pho o unable Su ace In e ac ions.
E a h, J., Cui, J., Schmid, J., Kappl, M., del Campo, A., Fe y, A., Langmui ,
2013. 29: p. 12138-12144
Achie emen s
•Bes lec u e awa d: So colloidal p obe AFM: A new me hod o he in es i-
ga ion o adhesion and con ac o so su aces, ACS Sp ing Mee ing 2010 (Bio-
unc ional A chi ec u es Symposium), San F ancisco, USA, Ma ch 21-15, 2010
•Bes pos e awa d: Co ela ion o Local P essu e and Op ical Response o
Mechano esponsi e Polyelec oly e B ushes, In e na ional Con e ence on Scan-
ning P obe Mic oscopy on So Polyme ic Ma e ials: SPM on SPM 2012, Ke k ade,
The Ne he lands, Sep embe 23-26, 2012
•Highligh ed Publica ion: Di ec Co ela ion be ween Local P essu e and Flu-
o escence Ou pu in Mechano esponsi e Polyelec oly e B ushes, published in
Angewand e Chemie in e na ional Edi ion, 2011 was highligh ed in: Na u e Ma-
e ials, 10, 724, 2011
1
O e iew
3
CHAPTER 1. OVERVIEW 5
1.1 Ou line
This hesis add esses di ec measu emen s o he esponse om polyelec oly e (PE)
laye s, composed o polyelec oly e b ushes. In pa icula , sys ems ha a e s udied
a e polyelec oly e b ushes on ha d subs a es and laye s ha a e buil up o colloidal
building blocks, i.e. sphe ical polyelec oly e b ushes and PE micelles composed o
double-end- e he ed annealed polyelec oly e b ushes. Fo he in es iga ion o hese
so-called ”sma ” coa ings, coa ings ha can swi ch hei p ope ies in esponse o ex-
e nal s imuli (o ice e sa), a omic o ce (AFM) and op ical mic oscopy was used.
New echniques by means o combina ion o AFM and op ical mic oscopy we e de el-
oped. Also, es ablished physico-chemical echniques we e used o explo e and cha ac-
e ize p ope ies o he polyme b ush sys ems.
Sma coa ings a e an in e disciplina y esea ch ield and e e yone has some hing o
b ing o he able1: A chemis is o example in e es ed in de eloping new syn he ic
me hodologies o in s udying polyme iza ion in he con ined dimensions o a hin ilm;
an enginee is in e es ed in unde s anding anspo phenomena and ba ie p ope ies
o new coa ings and o design new de ices; a biologis is in e es ed in biomime ic sys-
ems ha enable he eplica ion o in- i o condi ions and cellula in e ac ions; a nan-
o echnology o ien ed scien is hinks abou he unique nanoscale dimension by which
s uc u e-p ope y ela ionships can be de i ed; and a physicis is in e es ed in in e -
acial phenomena, in pa icula he unde s anding o con o ma ional changes and he
esul ing esponse.
We, me and my coope a ion pa ne s, add essed all o hese poin s. By combining
he capabili ies o he in ol ed g oups in polyme syn hesis, chemical cha ac e iza ion,
a omic o ce- and op ical mic oscopy, and mic o-mechanical modeling, we de eloped
new polyme b ush sys ems ha show unique p ope ies, cha ac e ized hese sys ems,
eme ged an unde s anding o he obse ed esponse and ela ed his o possible applica-
ions. Examples a e he a ional design o senso s, ac ua o s, and e e sible adhesi es.
1.2 Con en o he Indi idual Chap e s
A e an in oduc ion Chap e 2 gi es a e iew o he s a us o esea ch on PE lay-
e s and o hei heo e ical ea men . In pa icula he mos impo an aspec s o
PEs, unc ionaliza ion o su aces wi h PEs, and p ope ies o polyme b ushes a e
discussed. Fu he mo e he expe imen al echniques, i.e. AFM and op ical mic oscopy
1The ollowing passage is adap ed om Re . [1].

CHAPTER 1. OVERVIEW 6
and undamen als o in e ac ion o ces and con ac mechanics ha a e ele an o he
expe imen s p esen ed in his hesis a e in oduced.
The hesis consis o i e indi idual chap e s ha p esen issued publica ions in Chap-
e s i e o nine and wo k in p og ess ha is p esen ed as d a s in u he pe -
spec i es (Chap e 8).
The i s pape (Chap e 3) p esen s a no el me hod ha can be used o s udy adhe-
sion and con ac phenomena o su aces based on a so colloidal p obe (SCP), a ached
o an AFM can ile e using he Johnson, Kendall, and Robe s (JKR) app oach. In he
second pa (Chap e 4), a no el me hod is es ablished o map con ac s esses wi h
unp eceden ed p ecision using mechanosensi i e polyme b ush laye s. This sys em is
calib a ed using he SCP p obe echnique, in oduced in Ch. 3.
Fu he , polyme b ushes can be used o he design o esponsi e laye sys ems and o
une su ace p ope ies, such as we abili y, adhesion, and ic ion. Chap e 5 p esen s
an app oach o g adual uning o su ace in e ac ions based on pho o- esponsi e poly-
me b ushes.
Also, esponsi e laye s can be buil om colloidal building blocks. In e ac ion p ope -
ies o sphe ical polyme b ushes (SPBs) wi h mul ilaye s as a unc ion o ionic s eng h
a e s udied in Chap e 6. The measu emen esul s can be used o explain and o
egula e he abso p ion beha io o SPBs and o design unc ional laye sys ems.
Fu he , highly sensi i e coa ings a e designed, based on block copolyme micelles.
These coa ings a e in es iga ed wi h espec o hei swelling beha io which depends
on pH and ionic s eng h (Chap e 7). Also he esul ing changes in hei po osi y
and mechanical p ope ies a e s udied.
In Chap e 8 u he pe spec i es o mechano esponsi e sys ems a e ad essed. A e
discussions abou u he possibili ies o di ec measu emen s o con ac s esses o so
ma e ials (Ch.8.1), mechano esponsi e polyme b ush sys ems a e used in Ch. 8.2
o s udy con ac and adhesion o biomime ic adhesi es. Ch. 8.3 shows possibili ies o
enhance he sensi i i y and esolu ion o he mechano esponsi e polyme b ushes by
a ional design o he b ush laye s.
So Colloidal P obe AFM
Chap e 3: ”So Colloidal P obe AFM” [2] in oduces a no el echnique o cha ac-
e ize adhesion and con ac on he mic on scale.
Such phenomena a e impo an o all kinds o so ma e in e ac ions. Cu en issues
o esea ch a e in e ace phenomena in biological sys ems, as cell mig a ion o cellula
CHAPTER 1. OVERVIEW 7
di e en ia ion. Unde s anding he adhesi e p ope ies o cells o he subs a e will help
o con ol such beha io . Ano he impo an esea ch ield is minia u iza ion o com-
ponen s. The pe o mance o nano and mic onscale componen s is de e mined by hei
in e acial p ope ies. Such, o ma e ials selec ion, de ice design, and pe o mance ac-
cu a e de e mina ion o he in e acial p ope ies is necessa y. Also o g owing in e es
a e in e acial p ope ies o complex syn he ic sys ems, e.g. polyme b ushes, mul i-
laye s and pa e ned su aces, since such sma coa ings can ailo su ace p ope ies
like we abili y, adhesion, pe meabili y o op ical ea u es.
Requi emen s o he cha ac e iza ion o adhesion and con ac phenomena a e ha
in o ma ion on he mic on-sized con ac zone and on dynamics o con ac o ma ion
is accessible. He e, we in oduce a no el app oach o he in es iga ion o such phe-
nomena o so ma e su aces ha combines ad an ages o a mac o scale me hod,
he so-called ”JKR appa a us” and a mic o-scale me hod, namely colloidal p obe (CP)
a omic o ce mic oscopy (AFM).
In his so colloidal p obe (SCP) AFM echnique an elas ome ic colloidal p obe, made
o polydime hylsiloxane (PDMS) is a ached o an AFM can ile e , ende ing he con-
ac a ea be ween p obe and sample much la ge as compa ed o s anda d CPs (e.g.
composed o silicon o glass). This allows o de e mine he con ac beha io o he
p obe, i.e. he con ac a ea, ia in e e ome y as a unc ion o applied load (Figu e
1.1A). The load can be con olled wi h subnanonew on p ecision using he AFM eed-
back loop. We could show ha he con ac si ua ion can be desc ibed using a con ac
mechanics model de eloped by Johnson, Kendall, and Robe s (JKR).
In o de o es ablish he echnique, we de eloped a p o ocol o he SCP p epa a ion
and sol ed he p oblem o op ical le e sensi i i y de e mina ion o can ile e s unc-
ionalized wi h so p obes. SCPs made o PDMS wi h a diame e in he o de o
10 µmand a Young’s modulus in he o de o 1 MPa we e p epa ed ia suspension
polyme iza ion o he p ecu so polyme in enside solu ion. SCPs whe e a ached o
he can ile e in o de o ensu e an adequa e (la ge enough) con ac a ea be ween he
pa icle and he can ile e .
In o de o measu e adhesion ene gies, we p essed he SCP agains he subs a e o
choice and eco ded he con ac a ea by mic o in e e ome y (i.e. e lec ion in e e -
ence con as mic oscopy: RICM) in si u. Fi ing he da a wi h he JKR heo y yields
he adhesion ene gy: he con ac a ea (a) can be desc ibed as a unc ion o applied
load (P), elas ic p ope ies (K) and wo k o adhesion (w), a= (P, K, w), and all pa-
ame e s excep he wo k o adhesion a e known (Figu e 1.1B). We es ed his me hod
a ambien condi ions as well as in aqueous media on well-known su ace chemis ies
CHAPTER 1. OVERVIEW 8
A
B
Figu e 1.1: The so colloidal p obe echnique: 1.1A Expe imen al se up, 1.1B Anal-
ysis o he he modynamic wo k o adhesion
CHAPTER 1. OVERVIEW 9
and can clea ly sepa a e he con ibu ions o capilla y o ces in ai , hyd a ion o ces,
and hyd ophobic in e ac ions in wa e .
Full ensemble o da a ( o e e y load wcan be de e mined) and he la ge con ac a ea
make he SCP app oach an ou s anding me hod o adhesion measu emen s wi h an
enhanced sensi i i y. Addi ionally i is possible o s udy so ma e con ac si ua ions
a con olled condi ions on he mic on scale. This ac can be exploi ed o in es iga e
s ess sensi i e sys ems, because he local s ess can be de e mined om JKR heo y
o an adjus ed applied load. In he con ac zone he sample unde in es iga ion is
exposed o a ious p essu es and i s esponse can be analyzed.
Mechano esponsi e Polyelec oly e B ushes
Chap e 4: ”Mechano esponsi e Polyelec oly e B ushes” [3] in oduces a p omising
echnique o local de ec ion o s ess dis ibu ions wi h ou s anding esolu ion. The e-
o e s ess is ansla ed by a mechano esponsi e polyelec oly e b ush in o an op ical
ou pu .
Accu a e knowledge o s ess dis ibu ion in he con ac a ea is c ucial o unde s and-
ing so ma e con ac si ua ions. The key challenge in he expe imen al s udies o
s ess dis ibu ions in so ma e con ac s is he demand o combining high s ess sen-
si i i y (on he o de o kPa) wi h high la e al esolu ion (below mic ome e ). Classical
solu ions, such as s ess senso s (o en called p essu e senso s) using he de lec ion o
mechanical elemen s like memb anes as a means o quan i ying s esses a e eaching
undamen al limi s in e ms o he la e al dimensions. E en mos sophis ica ed mic o-
elec omechanical sys em app oaches (MEMS) ha e so a only eached he p essu e
sensi i i y o la e al dimensions o >> 10 µm. Mechano esponsi e ma e ials e en in
hei ea ly s ages o de elopmen s, o e come hese undamen al limi a ions. In hese
sys ems, a mechanical s imulus di ec ly a ec s he elec ical, chemical o op ical p op-
e y o a ma e ial senso . Fo hese ma e ial based app oaches, he limi ing ac o in
e ms o la e al esolu ion is how locally he ma e ial esponds o ex e nal p essu e and
how accu a ely hese changes can be ead ou .
Polyme b ushes a e pa icula ly in e es ing in his espec , since hey consis o in-
di idual, su ace g a ed, bu no la e ally c osslinked polyme s. The weak la e al
coupling, indeed, is a necessa y condi ion o high la e al esolu ion. A he same ime,
polyme b ushes a e hemsel es so ma e sys ems and hus ma ch he ypical ange
o elas ic p ope ies and de o mabili y, allowing o sui able sensi i i y. The key chal-
lenge howe e is o modi y he polyme b ushes such ha hei comp ession s a e can
CHAPTER 1. OVERVIEW 16
A B C
Figu e 1.4: In e ac ions o Sphe ical Polyelec oly e B ushes: 1.4A Design o he
SPBs, 1.4B In e ac ions o SPB wi h PE unc ionalized subs a es, 1.4C Adso p ion
beha io o SPBs depending on he sal concen a ion.

CHAPTER 1. OVERVIEW 17
ac ion o ex e nal s imuli a e a e y a ac i e esea ch ield ega ding i s po en ial
applica ions (as shown abo e). Examples a e d ug deli e y, mic o luidic sys ems, cell
issue enginee ing, as well as sensing, o ac ua ion.
Ou goal was o c ea e highly esponsi e and s able coa ings. The e o e we used mi-
cells ha a e composed o a hyd ophobic polybu adiene co e, an annealed anionic
poly(me hac ylic acid) polyme b ush shell and a quenched ca ionic co ona o qua e -
nized poly(2-(dime hylamino)e hyl me hac yla e) as building block. These micelles
we e assembled om solu ion (pH 4 bu e , whe e he shell is uncha ged) wi h a
quenched polyanion (anionic poly(sodium 4-s y enesul ona e: PSS) in o mul ilaye s
as sca ched in Figu e 1.5A using he laye -by-laye (LBL) app oach. This sys em
combines he ad an ages o he highly esponsi e annealed polyme b ushes, he unc-
ionali y and in e nal hie a chy o colloidal building blocks and he simple p epa a ion
p ocedu e o LBL ilms.
These mul ilaye a e s udied wi h espec o mo phology, po osi y swelling deg ee and
he co esponding mechanical p ope ies dependen on he composi ion o he ilm and
he su ounding medium. Using ellipsome y, AFM imaging and o ce spec oscopy we
ollowed he pH igge ed e e sible swelling and con ac ion o he mul ilaye ilms and
he esul ing mechanical p ope ies. Also, he dependence on he numbe o deposi ion
s eps was in es iga ed.
We could show ha mo phology and po osi y s ongly depend on he numbe o de-
posi ion s eps. The po osi y can be uned be ween 0% and 50% o 20 o 1 deposi ion
s eps, espec i ely. The po osi y has a big in luence on he wa e up ake and he
co esponding swelling beha io . We could a y wa e up ake by a ound wo o de s
o magni ude and he swelling deg ee by mo e han h ee o de s o magni ude. The
swelling dec eases wi h inc easing ilm hickness.
Po e opening and closing and he esul ing deg ee o swelling can be egula ed by he
solu ion pH (be ween pH 4 and pH 12). We obse ed a 6- old inc ease in ilm hickness.
This could be associa ed o an inc ease in Young’s modulus om a ew kPa o hund eds
o kPa (Figu e 1.5B).
Fu he Pe spec i es
Chap e 8: ”Fu he Pe spec i es” add esses new aspec s o he mechano esponsi e
sys ems based on ca ionic polyme b ushes (Ch. 4). Unde s anding he na u e and he
dis ibu ion o s esses a he con ac s o de o mable solids is undamen al o he ields
o so mechanics and adhesion. The esul s o mechano esponsi e sys ems based on
CHAPTER 1. OVERVIEW 18
A
B
Figu e 1.5: Swelling o Block Copolyme Micelles: 1.5A Micelles a e composed o a
hyd ophobic polybu adiene co e, an annealed anionic poly(me hac ylic acid) polyme
b ush shell and a quenched ca ionic co ona o qua e nized poly(2-(dime hylamino)e hyl
me hac yla e). These micelles a e assembled in laye -by-laye ilms using PSS. 1.5B
Response o block copolyme micelles o pH.
CHAPTER 1. OVERVIEW 19
ca ionic polyme b ushes a e e y p omising, and se e al undamen al aspec s can be
add essed o ully un old he po en ial o his de ec ion scheme (Ch.8.1).
Also, such su aces a e o pa icula in e es o he unde s anding o bioinspi ed e-
e sible adhesi es as will be discussed in Ch.8.2. Fu he , possible enhancemen o he
sensi i i y and esolu ion o he mechano esponse by a ional design o b ush laye s is
discussed in Ch.8.3.
CHAPTER 1. OVERVIEW 21
1.3 Indi idual Con ibu ions
This wo k is he ou come o close collabo a ions and knowledge ans e be ween di -
e en g oups and indi idual con ibu ions o di e se pe sons besides he au ho .
So Colloidal P obe AFM
•I de eloped he me hod, pe o med and analyzed all expe imen s, and w o e he
manusc ip .
•S. Schmid helped o de elop he me hod and co ec ed he manusc ip .
•A. Fe y analyzed he esul s, helped wi h discussions, and co ec ing he manusc ip .
Mechano esponsi e Polyelec oly e B ushes
•I de eloped he me hod o s ess de ec ion, pe o med and analyzed all expe -
imen s o s ess de ec ion, w o e pa s o he manusc ip and co ec ed he
manusc ip .
•J. Bünsow de eloped he syn hesis p o ocol o he mechano esponsi e polyme
b ushes, cha ac e ized he polyme b ushes, helped o de elop he me hod and
wi h he expe imen s o s ess de ec ion, w o e pa s o he manusc ip , and
co ec ed he manusc ip .
•P. M. Biesheu el helped o analyze and discuss he esul s.
•A. Fe y analyzed he esul s, helped wi h discussions, and co ec ed he manusc ip .
•W.T.S. Huck analyzed he esul s and inalized he manusc ip .
Pho o-Tunable Su ace In e ac ions
•I pe o med and analyzed all expe imen s o he cha ac e iza ion o su ace p op-
e ies o he polyme b ush, and w o e he manusc ip .
•J. Cui syn hesized and cha ac e ized he b ushes subs a es, and co ec ed he
manusc ip .
•J. Schmid helped wi h o ce spec oscopy measu emen s and he de elopmen o
he condensa ion mic oscopy echnique.

CHAPTER 1. OVERVIEW 22
•M. Kappl helped wi h he AFM measu emen s, pa icipa ed in discussions, and
co ec ed he manusc ip .
•A. del Campo analyzed he esul s, helped wi h discussions, and co ec ed he
manusc ip .
•A. Fe y analyzed he esul s, helped wi h discussions, and co ec ed he manusc ip .
In e ac ions o Sphe ical Polyelec oly e B ushes
•I pe o med he AFM in e ac ion measu emen s, analyzed hese expe imen s, was
in ol ed in scien i ic discussions, w o e pa s o he manusc ip , and co ec ed he
manusc ip .
•C. Hanske pe o med adso p ion expe imen s, he mic o con ac p in ing, an-
alyzed hese expe imen s, was in ol ed in scien i ic discussions, and w o e he
manusc ip .
•C. Küh and C. Schneide syn hesized and cha ac e ized he SPBs and he mi-
c opa icles.
•M. T ebbin p oduced a special designed s amp o mic o con ac p in ing using
so li hog aphy.
•A. Wi emann de eloped he syn hesis p o ocol o he SPBs, was in ol ed in
scien i ic discussions, w o e pa s o he manusc ip , and helped co ec ing he
manusc ip .
•A. Fe y analyzed he esul s, helped wi h discussions, and co ec ed he manusc ip .
Swelling o Block Copolyme Micelles
•I pe o med colloidal p obe AFM measu emen s, was in ol ed in scien i ic dis-
cussion, w o e pa s o he manusc ip , and co ec ed he manusc ip .
•J. Gensel and I. Dewald pe o med mos o he expe imen s, and analyzed hese
expe imen s. J. Gensel w o e he manusc ip .
•E. Be hausen conduc ed he syn hesis and cha ac e iza ion o he polyme used,
was in ol ed in scien i ic discussions, and co ec ed he manusc ip .
CHAPTER 1. OVERVIEW 23
•A. H. E. Mülle helped wi h discussions, and co ec ed he manusc ip .
•A. Fe y analyzed he esul s, helped wi h discussions, and co ec ed he manusc ip .
Fu he pe spec i es
Di ec measu emen s o con ac s esses o so ma e ials o
a ional design o e e sible adhesi es
•I w o e he manusc ip .
•M. Chaudu hi helped wi h discussions.
•A. del Campo helped wi h discussions.
•A. Fe y helped wi h discussions.
Con ac and Adhesion o Biomime ic Pa e ned Adhesi es
•I de eloped he me hod o s udy s ess dis ibu ions o biomime ic con ac s,
pe o med and analyzed he expe imen s and w o e he manusc ip .
•D. D o le p oduced mas e s o he biomime ic subs a es and pe o med he
adhesion and he SEM measu emen s.
•I. Dewald syn hesized and cha ac e ized he mechano esponsi e b ush subs a es.
•J. Bünsow helped o de elop he me hod o s udy s ess dis ibu ions o biomime ic
con ac s, de eloped he syn hesis p o ocol o he mechano esponsi e b ush sub-
s a es, and co ec ed he manusc ip .
•M. Chaudu hi helped wi h discussions.
•A. del Campo analyzed he esul s, helped wi h discussions, and co ec ed he
manusc ip .
•A. Fe y analyzed he esul s, helped wi h discussions, and co ec ed he manusc ip .
CHAPTER 1. OVERVIEW 24
Tuning he esponse o mechano esponsi e b ushes
•I pe o med and analyzed all expe imen s, de eloped he heo e ical models, and
w o e he manusc ip .
•J. Neubaue and I. Dewald syn hesized he b ush subs a es. J. Neubaue helped
wi h o ce spec oscopy expe imen s and he analysis o he da a.
•S. Block helped o analyze he expe imen s, and de eloped he heo e ical model.
•J. Bünsow helped wi h discussions.
•S. Ca egal and W. Pa ak de eloped he syn hesis p o ocol o a achmen o
SNARF molecules.
•A. del Campo helped wi h discussions.
•A. Fe y helped wi h discussions.
1.4 Re e ences
[1] Knoll. Func ional Polyme Films. Vol. 1. Wiley-VCH. Weinheim, Ge many,
2011.
[2] J. E a h, S. Schmid , and A. Fe y. “Cha ac e iza ion o adhesion phenomena
and con ac o su aces by so colloidal p obe AFM”. In: So Ma e 6.7 (2010),
pp. 1432–1437.
[3] J. Bunsow e al. “Di ec Co ela ion be ween Local P essu e and Fluo escence
Ou pu in Mechano esponsi e Polyelec oly e B ushes”. In: Angewand e Chemie-
In e na ional Edi ion 50.41 (2011), pp. 9629–9632.
[4] J. E a h e al. “Pho o unable su ace in e ac ions”. In: Langmui 29.39 (2013),
pp. 12138–44.
[5] C. Hanske e al. “Adso p ion o Sphe ical Polyelec oly e B ushes: om In-
e ac ions o Su ace Pa e ning”. In: Zei sch i Fu Physikalische Chemie-
In e na ional Jou nal o Resea ch in Physical Chemis y and Chemical Physics
226.7-8 (2012), pp. 569–584.
[6] J. Gensel e al. “Re e sible swelling ansi ions in s imuli- esponsi e laye -by-
laye ilms con aining block copolyme micelles”. In: Chemical Science 4.1 (2013),
pp. 325–334.
2
Theo y and S a us o he Field
25
CHAPTER 2. THEORY AND STATUS OF THE FIELD 32
chain a e pa ame e s o cha ac e ize PEs [16]. The bulk concen a ion Cjo species j
leads o an ionic s eng h I(in mol/l) o
I=1
2X
j
z2
jCj(~ ),(2.9)
and he local cha ge densi y ρ(~ )is ela ed o he local ion concen a ion cjby
ρ(~ ) = eX
j
zjcj(~ ),(2.10)
whe e eis he elemen a y cha ge, cjlocal ion concen a ion, and zj he alency o
species j.
Fo PEs, he excluded olume (monome -monome epulsion) is much la ge compa ed
o neu al polyme s due o he elec os a ic Coulomb po en ial ha de e mines he
con o ma ion and in e ac ions o he polyme .
The Coulomb po en ial u(~ )is de e mined by he Poisson equa ion o elec os a ics
∇2u(~ ) = −ρ(~ )
,(2.11)
whe e 3is he dielec ic pe meabili y. Dissol ing he PE in aqueous (sal ) solu ion
(elec oly e solu ion) leads o immobilized coun e -cha ges, i.e. coun e ions ha main-
ain elec ic neu ali y and a e a ac ed by he cha ged uni s o he PE. A ac ion
leads o sc eening o he Coulomb in e ac ions. The dis ibu ion o he mobile coun-
e ions is go e ned by he elec ic ield a ound he PE and he balance o elec os a ic
ene gy and en opic con ibu ions (S∝kBTln( )) [22].
The Coloumb po en ial o he PE is de e mined by he Poisson equa ion Eq. 2.11 and
depends on i s geome y
u(~ )∝








1/ o a poin like sys em
o a plana sys em
ln( ) o a line like sys em.
(2.12)
Fo a poin like sys em, he en opic con ibu ion o he ene gy is la ge compa ed
o he elec os a ic ene gy and coun e ions a e unbound. Fo a plana sys em mos
coun e ions a e bound o he su ace and o m he so called Gouy-Chapman laye (Eq.
3·0≡

CHAPTER 2. THEORY AND STATUS OF THE FIELD 33
2.28). In case o a line like cha ge he balance depends on he cha ge densi y (bo h
con ibu ions ∝ln ).
I he PE sys em (i.e. a cha ged su ace) is in he modynamic equilib ium he esul ing
cha ge densi y o he ions a posi ion ~ ollows a Bol zmann-like beha io
ρj(~ ) = Cjexp(−uij(~ )
kBT).(2.13)
The many-body in e ac ions uij can be a e aged and app oxima ed by a mean ield
po en ial o low molecula weigh and weakly cha ged PEs. Following he heo y o
Debye Hückel (DH) he mean ield po en ial can be exp essed as
umean =zjehφ(~ )i(2.14)
whe e in e -pa icle co ela ions a e neglec ed and hφ(~ )iis a ime-a e aged po en ial
(each coun e ion in e ac s wi h a di use cloud o he o he coun e ions). Addi ionally,
elec o neu ali y can be assumed
X
j
zjeCj
= 0.(2.15)
Inse ion in o Eq. 2.11 yields he Poisson Bol zmann equa ion (PB equa ion), connec -
ing he elec os a ic po en ial o he cha ge densi y o he ions
∇2umean =X
j
zje
Cjexp(−umean
kBT).(2.16)
Fo weak po en ials umean << kBT/zj , his equa ion can be expanded using a Taylo
se ies and hen linea ized. This esul s in he Debye Hückel equa ion [23]:
∇2umean =1
λ2
D
umean,(2.17)
wi h he so called ”Debye leng h” λD
λD=sKbT
Pj(z2
jCj(~ ))e2= KbT
2Ie2.(2.18)
CHAPTER 2. THEORY AND STATUS OF THE FIELD 34
The Debye Hückel equa ion (2.17) can be sol ed (PE on a su ace) using
umean(~ ) = u0exp(−
λD
).(2.19)
This (2.19) shows ha he Debye leng h can be in e p e ed as a sc eening leng h o he
Coloumb po en ial (Figu e 2.3). Assuming an n:n sal solu ion (AnBn→An++Bn−)
he Debye leng h is λD=0.304 nm
n√I. Fo << λD he elec os a ic in e ac ions a e pu ely
Coulomb and o >> λD, he elec os a ic in e ac ions a e sc eened comple ely and
he beha io o he PE con e ges o a neu al polyme . I he elec oly e solu ion
sc eens he elec os a ic epulsion, he PE s a s o coil.
Two bounda y condi ions ha e o be ul illed. The i s condi ion demands ha he
o al cha ge (su ace cha ge plus he cha ge o he mobile ions) mus be ze o [24]. The
su ace cha ge densi y σand he dis ibu ion o he ions ρa e ela ed in he G aham
equa ion, wha can be deduc ed om elec o neu ali y condi ions o he sys em
σ=−Z∞
0
ρd =p8cKBTsinh eumean
2KBT≈umean
λD
.(2.20)
Fu he mo e he po en ial has o anish o la ge dis ances.
Fo nonlinea PB heo y one can show ha
u(~ ) = 2KBT
ze ln "1 + ξexp(−
λD
1−ξexp(−
λD#(2.21)
≈4KBT
ze ξexp(−
λD
) o >> λD,(2.22)
wi h ξ= anh(zeuo)/(4KBT)[24]. In summa y he po en ial o a PE decays wi h he
debye leng h. The p e ac o depends on he geome y o he objec and he bound-
a y condi ions (see Ch. 2.3 o mo e de ails on he in e ac ions o wo cha ged su aces).
Howe e , hese app oxima ions ail in case o s ong cha ged PEs whe e coun e ions
condense o educe he elec os a ic po en ial. Tha meanes he coun e ions become
apped by he PE in o de o balance he elec os a ic ene gy by a dec ease in en opy.
Tha e ec is called ”coun e ion condensa ion” [25, 26]. Depending on he co espond-
ing pa ame e s, Coulomb in e ac ions o he loss o en opy domina e and de e mine
he coun e ion-dis ibu ion [16]. I he elec os a ic ene gy (Eq. 2.12) is small com-
pa ed o en opic con ibu ions, coun e ions canno be s abilized and no coun e ion
condensa ion occu s. Tha is he case i he numbe o cha ges pe uni leng h (Γ)
CHAPTER 2. THEORY AND STATUS OF THE FIELD 35
A
B
Figu e 2.3: 2.3A Po en ial o a PE: Umean( ) o (U0= 66 mV,T= 293.15 K and
ionic s eng h I= 0.1−0.001 M). Inse displays a log plo o hese po en ials. 2.3B
Debye leng h λD o a 1:1 sal as a unc ion o he ionic s eng h I.
CHAPTER 2. THEORY AND STATUS OF THE FIELD 36
is smalle han one cha ge pe Bje um leng h Γ<1/lB. The Bje um leng h lBis
de ined as he leng h a which wo elec on cha ges ha e an in e ac ion ene gy in he
magni ude o he he mal ene gy
lB=e2
4πKbT.(2.23)
In pu e wa e a s anda d lab p essu e and empe a u e lB≈0.7 nm. I he elec o-
s a ic ene gy is la ge compa ed o en opic con ibu ions (i he numbe o cha ges
pe uni leng h is highe han one cha ge pe Bje um leng h Γ>1/lB), coun e ion
condensa ion o he PE occu s o educe he cha ge densi y un il a maximum o one
cha ge pe Bje um leng h ρmax =e/lbis eached. Uncompensa ed coun e ions can
be desc ibed using he DH app oach. The e ec o coun e ion condensa ion can be
desc ibed using he model p oposed by Oosawa 4[27].
Due o elec os a ic e ec s, PEs a e qui e s i . This s i nes e ec can be desc ibed
using an elec os a ic pe sis ence leng h, ”Odijk leng h” Lp. One can show ha he
pe sis ence leng h Lpo he PE, desc ibing i s s i ness, is p opo ional o he Debye
leng h λ2
D o lexible poyelec oly es [28, 29, 30]. I he PE is dilu ed in an elec oly e
solu ion o low sal concen a ion, he polyme is s ongly s e ched (L=Lmax/(Γ/lB),
wi h L he leng h o he s e ched PE, Lmax he maximal leng h aligning he monome
uni s o he polyme , and Γ he numbe o cha ges pe uni leng h ( ice e sa o high
concen a ed elec oly e solu ions).
The excluded olume o PEs esul s in an inc eased excluded olume compa ed o
neu al polyme s due o he elec os a ic in e ac ions ( 2∝LpλD).
In case o annealed PEs, bo h he ionic s eng h and he pH o he solu ion s ongly
a ec he p ope ies o he polyme . The pH de e mines he deg ee o dissocia ion and
hus he ac ual cha ge densi y. This dependence makes such sys ems in e es ing o
many applica ions [31]. The chemical equilib ium o annealed PEs is desc ibed by a
modi ied e sion o he Hende son-Hasselbalch equa ion [16] which ela es he pH o
he solu ion and he ac ion o cha ged g oups. Fo molecula acids his esul s in:
pKa(app)=pH +log1−α
α(2.24)
4The PE is locally s i en and can be app oxima ed as a cylinde , ha aps all coun ions inside a
cylind ic cell [27]
CHAPTER 2. THEORY AND STATUS OF THE FIELD 37
whe e αdesc ibes he ac ual deg ee o dissocia ion and he pKais de ined by he law
o mass. O e beek showed ha he expe imen ally obse ed appa en pKa(app)(Eq.
2.24) o an annealed PEs, depends on he in insic alue pK0
a
pKa(app)=pK0
a+1
ln(10)RT
dG
dα (2.25)
wi h he e m dG/dα desc ibing he wo k necessa y o ca y cha ges agains he elec-
os a ic a ac ion om a PE o in ini e dis ance [32]. In o he wo ds, he second e m
ep esen s he shi in he dissocia ion cons an due o changes in he elec os a ic ee
ene gy o a PE upon a ia ion o he numbe o cha ged g oups [1].
In con as o neu al polyme s (Ch. 2.2.1), he s uc u al p ope ies o adso bed PEs
a e mos ly domina ed by elec os a ic in e ac ions. A cha ged su ace can be neu al-
ized by a opposi ely cha ged PE, which is en opically a o able and he e o e p omo es
PE adso p ion [20, 33, 34, 35, 36]. Se e al heo e ical app oaches like sel -consis en
ield heo y (SCF), Mon e-Ca lo simula ions, o scaling app oaches ha e been applied
o desc ibe he adso p ion beha io . Possible con o ma ions depending on he adso p-
ion ene gy a e so called ains (all PEs a e in con ac wi h he subs a e), loops (pa s
o he PE a e no in con ac wi h he subs a e), and ails (non-adso bed ends o he
PE) as ske ched in Figu e 2.4A [37, 38]. One adso bed laye o PEs has a hickness in
he o de o he chain diame e (≈1 nm).
The adso p ion is accomplished by a con inemen o he PE, which in ol es an inc ease
in ee ene gy. Fo compensa ion o his inc ease an addi ional a ac i e in e ac ion
mus s abilize he adso p ion. The d i ing o ces o adso p ion a e he gain o en opy
by complexa ion wi h opposi ely cha ged su aces and elease o coun e ions as well as
he elease o sol en molecules, on he ul illmen o elec o neu ali y. Howe e , o en
mo e PEs a e adso bed han necessa y o elec oneu ali y, which is called ”cha ge
o e compensa ion”. This can lead o a cha ge e e sal o he su ace.
Since elec os a ic in e ac ions a e dominan , pa ame e s like su ace cha ge, ionic
s eng h, pH and he a chi ec u e o he PE go e n he adso p ion. I depends on he
balance be ween elec os a ic and non-elec os a ic in e ac ions whe he an inc ease in
sal concen a ion leads o an inc ease o dec ease in adso p ion [39]. Two egimes
we e p oposed o desc ibe his e ec . In he so called ”sc eening educed” adso p ion
egime (high su ace cha ge, low cha ge densi y o he PE, weak non-elec os a ic con-
ibu ion), Coulomb in e ac ions be ween segmen s and he su ace domina e. I he
a ac ion be ween polyelec oly e and su ace is pu ely elec os a ic only his egime

CHAPTER 2. THEORY AND STATUS OF THE FIELD 38
is alid. Se e al adso bed laye s o PE a e possible, due o he long ange na u e o
he Coulomb in e ac ions. The adso bed amoun dec eases wi h an inc ease in ionic
s eng h due o sc eening e ec s. The PE can be eleased om he su ace when a
c i ical sal concen a ion is eached. In he egime o ”sc eening enhanced” adso p ion
(gene ally quenched PEs) non-elec os a ic in e ac ions (sho ange in e ac ions) be-
ween he segmen s and he su ace a e dominan . The adso p ion inc eases wi h ionic
s eng h because sal sc eens he epulsion be ween he equally cha ged g oups on he
polyme . In he in e media e case, when bo h o ces a e o oughly equal impo ance,
changing he sal concen a ion will ha dly a ec he adso p ion [39]. The di e en
adso p ion egimes a e shown in Figu e 2.4B
The adso bed laye hickness can be calcula ed by minimizing he ee ene gy [40, 41].
Assuming ha he Debye leng h λDis la ge han he adso bed laye hickness d( alid
o no oo high ionic s eng h, see 2.18), wo egimes can be ob ained o he laye
hickness: one o ela i ely la ge sal concen a ions (o a he s i polyme s) and
small laye hickness and one whe e he laye hickness is la ge han he pe sis ence
leng h bu smalle han he sc eening leng h
d∝






ln(lBσSΓL2
P
lBσSΓL1/3
P3/5
o d<λD< Lp
LP
lBσSΓ1/3 o Lp< d < λD
(2.26)
wi h σS he cha ge densi y o he su ace, Γ he cha ge densi y o he chain, and Lp
he e ec i e pe sis ence leng h [41].
2.2.3 Sel Assembly o Polyelec oly es
I PEs a e dissol ed in aqueous solu ion wi h sui able coun e pa s ha a e opposi ely
cha ged, hey o m agg ega es due o elec os a ic in e ac ions (o he in e molecula
o ces a e possible as well) [42]. These agg ega es can build up in e polyelec oly e
complexes (IPECs), which o m a new class o mac omolecules [43, 44]. The com-
plexa ion is d i en by he elease o coun e ions which leads o an inc ease in en opy.
Se e al heo ies and s udies exis o desc ibe he ea u es and physical p ope ies o
he esul ing IPECs [45]. IPECs can consis o a PE wi h a second opposi ely cha ged
PE, wi h low molecula coun e ions, ionic su ac an s, colloidal pa icles, and o he s
(Figu e 2.5A). These IPECS a e in e es ing o nume ous applica ions. Examples a e
he build up o polyelec oly e mul ilaye s, whe e many opposi ely cha ged PEs a e
adso bed in laye s in al e ing o de [46].
CHAPTER 2. THEORY AND STATUS OF THE FIELD 39
A
B
Figu e 2.4: Adso p ion o PEs: 2.4A Adso bed polyelec oly e chain o m ains,
loops and ails. 2.4B Di e en Adso p ion egimes o PEs depending on cha ge densi y
and sal concen a ion: (I) low cha ge densi y, low sal concen a ion: o ma ion o
loops and ails, high adso bed amoun ; (II) PE has he same cha ge as he subs a e,
low sal concen a ion: PE eleases om he su ace; (III) s ong cha ge densi y, low
sal concen a ion: PE lies la and s able on he su ace, weake adso p ion as in
(I); (IV) low cha ge densi y, high sal concen a ion: sc eening o elec os a ic in e -
ac ions, adso p ion amoun can inc ease o dec ease; (V) PE has he same cha ge as
he subs a e, high sal concen a ion: elec os a ic epulsion is sc eened, adso p ion
is possible; (VI) high cha ge densi y, high sal concen a ion: simila o (I) due o
sc eening o elec os a ic in e ac ions; (VII) abo e a c i ical sal concen a ion all PEs
elease om he su ace.
CHAPTER 2. THEORY AND STATUS OF THE FIELD 40
I he polyme consis s o wo o mo e blocks, ha a e dis inguishable by he chemi-
cal and physical p ope ies and linked by co alen bonds, he sys em phase sepa a es
and can sel -assemble o complex s uc u es like sphe es, cylinde s, o lamellae. These
di e en a chi ec u es esul in a big numbe o unc ionali ies, as epo ed in Re .
[47]. The geome y and he physical p ope ies o hese complex sys ems a e unable
by pa ame e s like block leng h, numbe o blocks, sol en quali y, ionic s eng h, and
-in case o annealed PEs- pH. The complexi y o he s uc u es and he numbe o
di e en mo phologies inc ease d as ically wi h he numbe o blocks, as o example
desc ibed o ABC iblock e polyme s in Re . [48]. When a block copolyme is dis-
sol ed a a concen a ion exceeding he c i ical micella concen a ion (cmc) and i one
o he blocks is soluble whe eas he o he is no hey o m micella s uc u es wi h a
sol ophobic co e and co ona poin ing in o he solu ion (Figu e 2.5B)[49].
A
B
Figu e 2.5: Sel assembly o polyelec oly es: 2.5A Fo ma ion o an in e polyelec-
oly e complexes ( ep oduced om [44] c
RSC). 2.5B Fo ma ion o a block copolyme s
micelle.
CHAPTER 2. THEORY AND STATUS OF THE FIELD 41
2.2.4 Func ionaliza ion o Su aces wi h Polyelec oly es
The e a e many possibili ies o unc ionalize su aces wi h PEs (Figu e 2.6). I is
beyond he scope o his wo k o explain all possible echniques in de ail. He e an
o e iew o e se e al echniques is gi en, ollowing he scope made in Re . [1].
Two ways o su ace unc ionaliza ions can be dis inguished: physical o chemical unc-
ionaliza ion. In case o physical unc ionaliza ion he molecules a e coupled o he
subs a e ia physical in e ac ions, while chemical unc ionaliza ion in ol es co alen
a achemen o molecules [50].
O en he Langmui Blodge echnique was ex ensi ely used o unc ionaliza ion o
su aces wi h polyme s [51] (Figu e 2.6A). A e equilib a ion o polyme monolaye s
a an ai -liquid in e ace he PEs we e ans e ed o a subs a e o choice by dipping
he subs a e in o he liquid. Using se e al dipping s eps, mul ilaye s can be ealized.
Howe e , his echnique has some limi a ions wi h espec o ype, opog aphy, and
size o he subs a e and equi es special equipmen . Ano he app oach o p oduce
sma su aces is based on sel -assembly o monolaye s (SAM) due o chemical adso p-
ion (Figu e 2.6B) [52, 53, 54, 55]. Mul ilaye s can be ob ained by a ge ed molecula
design o he monolaye s. Howe e , hese ilms a e limi ed o ce ain classes o co alen
o coo dina i e chemis y.
An elegan app oach o he o ma ion o unc ional su aces, is he laye -by-laye depo-
si ion echnique (LBL) (Figu e 2.6C). He e opposi ely cha ged PEs (o o he molecules)
a e deposi ed as ilms ia dipping, spin, o sp ay coa ing in al e ing o de on o he
sample subs a e. This p ocess is d i en by elec os a ic in e ac ions and he gain o
en opy by elease o coun e ions and sol en molecules and complex o ma ion (see
Ch. 2.2.3) [56]. The echnique was es ablished by Deche [57]5and has nowadays a lo
o applica ions, pa icula ly in he de elopmen o esponsi e coa ings [59, 60]. This
is due o ad an ages like easy handling, low cos equipmen , and no es ic ions wi h
espec o opog aphy, geome y, chemis y, and size o he subs a es. In addi ion,
he hickness o he ilm and he esul ing cha ge o he sample can be adjus ed by he
numbe o deposi ion s eps (1 up o a ound 1000), he PE used (e.g. molecula weigh
[61]), and he p ope ies o he solu ion (concen a ion, ionic s eng h, pH [62, 63] and
dipping ime) [64, 62]. Fo example LBLs a e used o biomedical applica ions and cell
subs a es [65, 66], o coa ings (walls) o mic ocapsules ha can be used o e.g. d ug
deli e y [67, 68], con oling su ace we abili y [69], o he design o op ical senso s
[70], o he p epe a ion o ligh emmi ing diodes [71], o uel cell memb anes [72]. The
5al eady i s epo ed by Ile [58]
CHAPTER 2. THEORY AND STATUS OF THE FIELD 48
he polyme b ush p ope ies a e unc ions o he dis ance om he su ace. Fo mo e
de ails, he eade is e e ed o [82].
The discussion so a was o neu al polyme s. I he monome uni s a e cha ged and
he g a ing densi y is high, a PE polyme b ush is o med. Fo sys em neu ali y,
coun e ions ha lead o an osmo ic p essu e a e p esen in he b ush (see Ch. 2.2.2).
The polyme chains a e s e ched by segmen -segmen in e ac ions and elec os a ic
(Coulomb) in e ac ions in equilib ium wi h he elas ic ee ene gy gained by he en-
opic es o ing o ce o he chain (see Ch. 2.2.1). These PE b ushes can be ei he
quenched (cha ges a e ixed inside he b ush), o annealed (cha ges a e mobile in he
b ush).
The cha ge can be accoun ed o he deg ee o ioniza ion α. The main impo an pa-
ame e s o PE b ushes 1/σ and αa e combined in he so called ”Gouy-Chapman”
leng h
Λ = σ
lBNα (2.28)
ha de ines he cha ac e is ic hickness o he coun e ion cloud (Figu e 2.10). I he
Figu e 2.10: Pa ame e s o a ca ionic polyme b ush in sal solu ion
chains a e densly packed (σsmall) and s ongly cha ged (la ge α) he Gouy-Chapman
leng h is small and can be smalle han he b ush heigh H(Λ< H). In ha case he
coun e ions a e apped inside he b ush and compensa e he immobilized cha ges o
he polyions. I he g a ing is ela i e spa e and he deg ee o ioniza ion is low, he
Guoy-Chapman leng h becomes la ge han he b ush heigh H(Λ> H). In ha case,
he coun e ions sp ead in o he solu ion beyond he edge o he b ush.

CHAPTER 2. THEORY AND STATUS OF THE FIELD 49
The analy ic exp ession o he cha ge and coun e ion dis ibu ions and he s uc u e
o he PE b ush can be calcula ed using sel -consis en ield heo y (SCF) [106, 107,
108, 109].
I he solu ion is sal ed, an addi ional sc eening o he Coulomb in e ac ions be ween
chain segmen s is p o ided by coions and coun e ions o he sal . This sc eening can
be desc ibed by he Debye sc eening leng h λD(see Eq. 2.18).
Fo an unde s anding o he physical beha io and he in e nal s uc u e o polyme
b ushes di e en models and app oaches can be used. The i s ime, he in luence
o con inemen on endg a ed polyme chains was s udied by Alexande [110] and de
Gennes [111] (AdG model). Using scaling a gumen s and desc ibing he b ush segmen s
as so called ”blobs”7 hey could show ha he densi y o he b ush eaches a homogenous
pla eau o σ < z < H and d ops down quickly o z > H, whe e zis he dis ance om
he su ace. This beha io can be desc ibed by a s ep p o ile (see Figu e 2.9C)
ρ∝N
Hσ (2.29)
o 0< z < H and ze o elswhe e. This co esponds o a b ush heigh o
H∝Nσ−1/3.(2.30)
The b ush heigh scales linea ly wi h he leng h o he a ached polyme .
To desc ibe he physics o polyme b ushes, models based on hese ideas and new
app oaches like SCF heo ies o nume ical me hods we e applied. Also, he cu a u e
o he subs a e, polydispe si y, changes in he en i onmen , and o he aspec s we e
aken in o accoun . To desc ibe all o his is much beyond o he scope o his wo k
and he eade is e e ed o example o Re . [77]. In he ollowing, jus some aspec s
will be discussed ollowing he conclusions o [107, 108, 109] ( o de ails see Appendix
A).
Di e en models a e alid o di e en limi s o beha io . In case o local compensa ion
o immobilized cha ges by mobile ions, he ”Local Elec on neu ali y App oxima ion”
(LEA) can be used [107]. This app oxima ion is applicable i Coulomb in e ac ions
in he polyme b ush a e sc eened by apped coun e ions o by added sal on a scale
smalle han he b ush hickness. On he con a y, i he sys em is unable o e ain
coun e ions inside he b ush, he sys em can be app oxima ed by a capaci o model
[112]. In gene al (mos o he expe imen al sys ems), jus a pa ial cha ge neu aliza ion
7one blob con ains a polyme segmen ha beha es like an ideal polyme
CHAPTER 2. THEORY AND STATUS OF THE FIELD 50
akes place and a ac ion o mobile ions sp eads beyond he edge o he b ush. In ha
case, Sel Consis en Field (SCF) is he heo y o choice [106, 107, 108, 109].
The LEA assumes ha he cha ge and he o ce is locally balanced inside he b ush
(see Appendix A o mo e de ails). In case o a neu al polyme b ush i is su icien o
balance be ween he s e ic excluded olume in e ac ions Fconc and he es o ing o ce
associa ed wi h he loss in en opy o he polyme chain upon s e ching Fcon (also
o en called as elas ic ene gy). Sol ing his balance esul s in a scaling law o he
b ush heigh , depending on he sol en quali y. In case o a good sol en , he b ush
heigh Hscales as ollows [107]:
H∝Nσ−1/3,(2.31)
which is he same as he esul o AdG (eq. 2.30). In case o PE b ushes, he sho ange
in e ac ions a e weak compa ed o elec os a ic o ces. He e elec os a ic in e ac ions
Fion a e balanced by Fcon . Addi ional balance o he cha ges leads o wo di e en
scaling egimes o PE b ushes in a sal solu ion whe e he b ush heigh scales linea ly
wi h he polyme con ou leng h [107]:
H∝Naα1/2, o cS< cCI (2.32)
H∝N(a2α2σ−1C−1
S)1/3, o cS> cCI,(2.33)
whe e CSis he sal concen a ion and CCI he concen a ion o he coun e ions.
PE b ushes ha can be desc ibed by eq. 2.32 a e called ”osmo ic b ush” (OsB). This
is he case i he sal concen a ion o he solu ion is low and he concen a ion o
coun e ions inside he b ush is equal o ha o he immobilized cha ge. An impo an
ea u e o he OsB is ha he a e age hickness is independen o he g a ing densi y
(Eq. 2.32). Abo e a ce ain sal concen a ion, sal ions domina e o e he immobilized
cha ges inside he b ush (Eq. 2.33) and a so called ”sal ed b ush” (SB) is o med. He e,
he b ush heigh dec eases con inuously wi h inc easeing sal concen a ion and g a -
ing densi y due o sc eening e ec s. Only ee coun e ions con ibu e o he osmo ic
p essu e. The ansi ion om he OSB egime o he SB egime occu s when he bulk
sal concen a ion equals he concen a ion o he ee mobile coun e ions.
Equa ions 2.32 and 2.33 a e qui e gene al and apply o bo h quenched and annealed
PE b ushes [107]. Fo quenched b ushes his is he inal esul . Fo he annealed case,
he si ua ion is mo e complex. The dissocia ion deg ee and he appa en pKa o he
PE b ush depend on i s local elec ic ield (en i onmen ), in pa icula on he solu ion
CHAPTER 2. THEORY AND STATUS OF THE FIELD 51
pH, he ionic s eng h, and on he g a ing densi y. In case o weak polyacid b ushes,
he pKa shi s o highe alues compa ed o he pKa o he polyme in bulk solu ion
(o ice e sa o basic b ushes). Adding sal o he solu ion shi s he appa en pKa
o lowe alues (close o pKa in bulk solu ion).
The deg ee o dissocia ion wi hin he b ush is close o ze o a low sal concen a ions.
I inc eases in he OsB egime and eaches he bulk le el (αBo an indi idual polyacid
molecule imme sed in he solu ion [113]) in he sal ed b ush egime.
Also, he b ush heigh is a ec ed by he ionic s eng h. Using scaling models o SCF
one can show ha he b ush heigh (o an annealed polyme b ush) passes a maximum
ha is loca ed a he OsB/SB ansi ion [107, 113, 114, 115, 116] (Figu e 2.11). In
addi ion, o annealed PE b ushes he b ush heigh is a unc ion o he solu ion pH.
The heigh inc eases o basic PEs wi h inc easing pH and dec eases unde acidic con-
di ions (o ice e sa o acidic PEs).
In addi ion o he OsB and he SB egime, ou o he b ush egimes can be dis inguished
which a e sepe a ed by he g a ing densi y and he deg ee o ioniza ion. Figu e 2.12
summa izes hese beha io s in phase diag ams o he sal - ee and he sal ed case
[107].
•Low g a ing densi y (small 1/σ); elec os a ic in e ac ions weak (small α) com-
pa ed o he olume in e ac ions (Fion << Fconc) lead o g a ed indi idual neu-
al coils (NC: mush oom egime H∝aN3/5ν1/5
2) o isola ed cha ged chains in
sal ed wa e (SC), espec i ely.
•Low g a ing densi y (small 1/σ), high elec os a ic in e ac ions (big α) lead o
isola ed g a ed polyions s e ched due o in amolecula Coulomb epulsion (IS:
H∝aNα2/3).
•High g a ing densi y, weak elec os a ic in e ac ions (small α) compa ed o ol-
ume in e ac ions (Fion << Fconc) lead o a quasineu al egime, meaning ha
he b ush beha es like a neu al b ush whe e he b ush heigh is balanced by he
equlib ium o en opic s e ching and s e ic in e ac ions (NB: H∝Nσ−1/3).
•In e media e egime (cha ged Pincus b ush (PB): H∝a2N3ασ−1): mobile ions
a e dis ibu ed in he space abo e he g a ing su ace (Λ> H). This egime
appea s jus in sal ee solu ions.
The abo e desc ibed LEA dono p o ide in o ma ion on he in insic s uc u e o ee
and con ined b ushes as a unc ion o he b ush pa ame e s (g a ing densi y, molecula
CHAPTER 2. THEORY AND STATUS OF THE FIELD 52
Figu e 2.11: B ush p ope ies as a unc ion o sal concen a ion: B ushheigh H
o quenched (solid line) and annealed (do ed line) b ushes and deg ee o dissocia ion
wi hin he b ush α o quenched (solid line) and annealed (do ed line) b ushes (adap ed
om ([113] c
Ame ican Chemical Socie y)
weigh , deg ee o ioniza ion, solu ion p ope ies). To ul ill hese equi emen s a heo y
is needed wich wo ks wi hou a p io i assump ions and ha gi e analy ic exp essions
o he densi y p o ile o he monome s, he equilib ium dis ibu ion o he mobile
ions inside and ou side he b ush, and he a e age hickness. An ansa z o sol e his
p oblem can be he sel -consis en ield heo y (SCF [108, 109, 116]). He e, he in insic
s uc u e is ob ained by minimiza ion o he o al ee ene gy o . The o al ee ene gy
has h ee epulsi e con ibu ions: 1) The con o ma ion ee ene gy which desc ibes
he s e ic epulsion be ween chain segmen s ( conc), 2) he ee ene gy associa ed o
he en opy Sion con ining coun e ions o a laye o hickness H:−KbTSion, and 3)
he di ec elec os a ic con ibu ion ion i he PE b ush is no locally elec o neu al
h oughou he sys em. The a ac i e con ibu ion o he o al ee ene gy o is he
en opic ee ene gy loss con [108].
o = con + conc + ion −KbTSion.(2.34)
Minimiza ion (o his unc ional) and ull exp essions o he indi idual e ms lead o
unc ions o he polyme densi y p o ile inside he b ush (pa abolic o m as sca ched in
Figu e 2.9C, o he b ush heigh , and o he cha ge densi y inside and ou side he b ush
and hus he speci ic elec os a ic po en ials. Fo de ails see Re . [108, 109, 116]. Also,
he su ace p essu e, he con o ma ion and he beha io o PE b ushes in con inemen
can be ob ained.
CHAPTER 2. THEORY AND STATUS OF THE FIELD 53
A
B
C
Figu e 2.12: Phase diag am o polyme b ushes ( ep oduced om [107] c
Ame ican
Chemical Socie y): Type o polyme b ush depending on he g a ing densi y σ−1and
deg ee o dissocia ion α o he sal ee case 2.12A and he sal ed case 2.12B. 2.12C
Heigh as a unc ion o he g a ing densi y σ−1along he black do ed line o 2.12B.
(Quenched polyme b ush: solid lines, annealed polyme b ush: do ed line)

CHAPTER 2. THEORY AND STATUS OF THE FIELD 54
Also, PE b ushes can be modeled using nume ical me hods, o example molecula
dynamics (MD) simula ions [117]. Resul s om SCF and MD simula ions show he
same beha io o polyme b ush pa ame e s.
2.3 Su ace and In e acial Fo ces
In e ac ions and adhesion play a majo oles in na u al science since hey con ol su -
ace p ope ies and a e c ucial o many applica ions especially o objec s o e ec s on
he colloidal scale (o de o mic ons). Examples a e coa ings o su aces wi h polyme s
o su ace p o ec ion [118], composi es [119], pain ings and adhesi es (o nons icking
su aces). Examples in na u e a e cell adhesion [120, 121], ecep o -ligand in e ac ions
[122], and he e ec o con ac shape o animal pads on hei s icking beha io [123].
De ails on heo e ical aspec s a e explained elsewhe e [33, 124, 125, 24, 126, 127]. He e,
jus an o e iew is gi en wi h emphasis explaining he obse ed sys ems and he used
echniques ha a e p esen ed in he indi idual chap e s. The p esen a ion is o ien ed
on [33, 124, 125, 24, 126, 127] and he ci ed li e a u e.
Su ace and in e acial o ces a e e.g. ionic, me allic, o co alen bonds, an de Waals
o ces, elec os a ic o magne ic in e ac ions as well as sol en o ces like hyd ophobic
and hyd ophilic in e ac ions, hyd ogen bonding and capilla y o ces. The ype o in-
e ac ion o ce depends on he ype o he in e ac ing ma e ial, i s en i onmen and
he dis ance (long ange 1−100 nm o sho ange <1 nm).
When wo bodies a e b ough in o con ac , he in e ac ion o ces lead o adhesion
and he bodies can de o m. The adhesion is cha ac e ized by he s ess and he wo k
needed o sepa a e he in e aces, plus aspec s like mechanical in e locking and in e -
pene a ion [126]. The o al adhesion o ce ( o ce needed o sepa a e wo bodies) is he
supe posi ion o all epulsi e and a ac i e o ces. The adhesion ene gy (also called
Dup és wo k o adhesion) is he sum o he su ace ene gies γo he con ac ing su aces
iand j(in medium m) lowe ed by he in e acial ene gy γij [24, 126]
wadh =γim +γjm −γij.(2.35)
I wadh is posi i e he bodies a ac each o he . I wadh is nega i e hey epel each
o he . Measu ed esul s a e in gene al lowe han his heo e ical alue due o su ace
he e ogenei ies, oughness and we ing e ec s.
CHAPTER 2. THEORY AND STATUS OF THE FIELD 55
2.3.1 The De jaguin App oxima ion
In e ac ion o ces F(D)o wo bodies o any shape can be ela ed o he in e ac ion
ene gy pe uni a ea w(D)be ween wo plana pla es as a unc ion o he sepa a ion
dis ance Dand he ma e ial p ope ies using he De jaguin app oxima ion8[128, 129].
Fo wo in e ac ing sphe es wi h adii Riand Rji can be shown ha
F(D)≈Z∞
D
2πRP(D∗)dD∗= 2πRw(D),(2.36)
whe e R=RiRj/(Ri+Rj)is he educed adius and P(D)is he no mal o ce pe
uni a ea ac ing be ween wo plana su aces (Figu e 2.13). This app oxima ion is
alid o any ype o in e ac ion i he cu a u e o he p obes is la ge compa ed o he
sepa a ion dis ance and he con o ma ion o he in e ac ing sys em is independen o
he dis ance om he su ace (e.g. no alid o SPBs).
Figu e 2.13: The De jaguin app oxima ion: Two in e ac ing sphe es wi h adii R1
and R2<< R1a sepa a ion dis ance D(adap ed om [128] c
Else ie ).
8This is help ul as in many cases i is much easie o model he in e ac ions o he plana case
and measu e o ces be ween sphe es o cylinde s.
CHAPTER 2. THEORY AND STATUS OF THE FIELD 56
2.3.2 Van de Waals In e ac ions
Van de Waals ( dW) o ces a e o uni e sal impo ance since hey exis be ween any
combina ion o molecules and su aces independen o he cha ge, he ma e ial, o he
su ounding medium [24, 126]. They a e he sum o di e se dipole-dipole in e ac ions,
i.e. Keesom, Debye and London in e ac ions. Keesom in e ac ions desc ibe he in e -
play be ween cons an dipoles o he molecules dependen on he o ien a ion and on he
absolu e empe a u e. Debye in e ac ions ake in o accoun dipole induced in e ac ions
wi h a cons an cha ge dependen on he o ien a ion. London dispe sion in e ac ions
ac be ween all molecules and ha e quan um mechanical o igin. They can be desc ibed
by luc ua ion induced dipoles. All po en ials desc ibing hese in e ac ions ha e a 1/ 6
dependence, whe e is he dis ance o he in e ac ing molecules:
U dW( ) = −CD+CK+CL
6=−CVdW
6(2.37)
and CD,CK,CLa e p opo ionali y cons an s conside ing he Debye (D), Keesom (K)
and London (L) con ibu ion. They accoun he cha ge, he pola i y, and he op ical
p ope ies o he molecules o a oms, and he su ounding medium.
In case o mac oscopic bodies, he o ce depends on he local dis ance o he bod-
ies (de e mined by he geome y). The in e ac ions can be app oxima ed using he
Hammake app oach (o mo e complex app oaches like he Li schi z heo y o spec al
me hods). Fo example, o he in e ac ion o wo sphe ical objec s wi h adii Riand
Rja dis ance D he VdW po en ial and he esul ing dW o ce be ween wo sphe es
can be app oxima ed wi h
U dW(D) = −AR
6D,
⇒F(D) = AR
6D2(2.38)
whe e A=π2CVdWρiρjis he Hammaka cons an (wi h ρ he molecula densi y o
he ma e ial) and R=RiRj/(Ri+Rj)is he educed adius o he sys em. In mo e
ex ended heo ies, Ais a complex unc ion o he empe a u e, he dielec ic p ope -
ies, and he abso p ion equencies o he ma e ial. Typical alues o he Hamake
cons an o condensed phases in acuum a e abou 10−19 J.
CHAPTER 2. THEORY AND STATUS OF THE FIELD 57
2.3.3 In e ac ions o Cha ged Sys ems
I he bodies a e cha ged, long ange Coulomb in e ac ions play a dominan ole. The
po en ial is de e mined by he Poisson equa ion (Eq. 2.11). Fo wo poin cha ges,
he in e ac ion po en ial is gi en by a 1/ dependency which can ei he be a ac i e
o epulsi e depending on he signs o he cha ges (Eq. 2.12). Fo mac oscopic bodies
he po en ial esul s, depending on he geome y, in di e se p opo ionali ies o he
dis ance (eq. 2.12).
In sol en , mos su aces a e cha ged, since i is ene ge ically a o able o cha ge he
su ace wi h espec o he he mal ene gy KBT[33]. This occu s by dissocia ion
o ionizable g oups o by he adso p ion o cha ged species (Ch.2.2.2). Fo elec o-
neu ali y, opposi ely cha ged coun e ions a e immobilized. This cha ging esul s in an
elec ic double laye consis ing o he so called inne ”S e n” o ”Helmhol z” laye whe e
coun e ions a e bound close o he su ace and he di use Gouy-Chapman laye con-
sis ing o a di use coun e ion a mosphe e [126] (Figu e 2.14). In elec oly e solu ions
he po en ial in he di use laye decays exponen ially ( a away om he su ace). This
beha io is desc ibed quan i a ely by he Debye sc eening leng h and is de e mined by
he PB equa ion (U∝e−Dλ−1
D, see Eq. 2.16). The PB equa ion ela es he ion dis i-
bu ion o he su ace po en ial, by using he elec o-neu ali y condi ion.
I wo cha ged su aces a e b ough nea o each o he , he ion dis ibu ion o e lap.
The e o e an inc ease o he osmo ic p essu e due o he inc ease o mixing en opy o
he ion clouds occu es and he elec os a ic double laye o ce a ise (Figu e 2.14A). One
can show ha i is enough o conside he coun e ion dis ibu ion a he midplane o
bo h su aces and he su ace cha ge densi y σS(con ac alue heo em 9). In addi ion
o elec o-neu ali y, he su ace cha ge densi y σSo he in e ac ing objec s in luences
he po en ial. Tha leads o addi ional bounda y condi ions. Th ee ypes can be iden-
i ied: 1) Cons an cha ge (cc: he su ace cha ge densi y is cons an . Sol ing he PB
equa ion esul s in a dis ance dependence be ween σS,0[24]), 2) he cons an po en ial
U0(cp): he su ace po en ial is independen o he dis ance, and 3) he cons an eg-
ula ion app oxima ion (c : he su ace cha ge depends on he cha ge densi y and on
he dis ance).
Taking in o accoun hese condi ions, he elec os a ic double laye o ce be ween wo
9gene al and also alid o o he in e ac ions
CHAPTER 2. THEORY AND STATUS OF THE FIELD 64
limi o 0.5 [24], whe eas glass has a Poisson a io o a ound 0.1 o example.
Con ac Mechanic Models
The i s model o desc ibe he con ac be ween wo non- adhe ing, iso opic, linea
elas ic sphe es was gi en by H. He z in 1881[143]. H. He z calcula ed he de o ma ion
δand con ac a ea aas a unc ion o applied load F, geome ical e ms (R=RiRj/(Ri+
Rj)), and ma e ial pa ame e s as accoun ed o he educed modulus K
K=4
31−ν2
i
Ei
+1−ν2
j
Ej−1
.(2.54)
The esul ing con ac pa ame e s as well as he s ess dis ibu ion σ( )in he con ac
zone (as a unc ion o dis ance om he axial cen e ) a e summa ized in Figu e 2.17
and Tab. 2.2 [127, 128]. Applying some simple con e sions, he o ce o achie e a
ce ain de o ma ion δcan be ob ained by
FHe z(δ) = KR1/2δ3/2.(2.55)
Taking adhesion in he con ac a ea in o accoun , Johnson, Kendall and Robe s (JKR)
Figu e 2.16: Con ac pa ame e s o a sphe e p essed agains a la subs a e
de eloped a mo e ealis ic model o so con ac s [144]. By balancing su ace ene gies
and he elas ic po en ial, hey calcula ed he con ac a ea and he de o ma ion as a
unc ion o applied load and su ace ene gy pe uni a ea w, as well as he esul ing
s ess dis ibu ion (Figu e 2.17 and Tab. 2.2). The JKR heo y is alid o so samples

CHAPTER 2. THEORY AND STATUS OF THE FIELD 65
wi h a la ge educed adius and la ge adhesion o ces. In case o ze o ex e nal load,
ini e con ac adius, de o ma ion, and s ess a e obse ed due o adhesion [127]
a0JKR =6πwR2
K1/3
,(2.56)
a a de o ma ion o
δJKR
0=a2
0
R−2
3 6πwa0
K.(2.57)
Due o he s eng h o adhesion, he in e ac ing bodies s ill adhe e while pulling (neg-
a i e loads) un il a c i ical o ce Fadh is eached (see Tab. 2.2). I should be no ed
ha he exp ession o he adhesion o ce is independen o he elas ic p ope ies o
he ma e ial. Fu he mo e, he aspec o expe imen ally obse ed adhesion hys e esis
can be explained using he JKR heo y. The con ac a ea is la ge when unloading
han in he loading case un il up u e a a c i ical con ac adius o ac= 0.63a0and a
(nega i e) de o ma ion o δc=−(πw2R/12K)1/3.
A he same ime De jaguin, Mulle , und Topo o (DMT) de eloped an al e na i e
model whe e adhesion is p esen a ound he con ac zone [145]. The DMT model as-
sumes ha he su ace p o ile is he same as o He zian con ac s. Adhesion is included
by an addi ional load caused by he su ace o ces a ound he con ac a ea. The DMT
heo y can be applied o con ac s o s i samples wi h small adii and small adhesion.
In case o ze o ex e nal load, ini e con ac adius, de o ma ion, and s ess occu
aDMT
0=2πwR2
K1/3
,(2.58)
a a de o ma ion o
δDMT
0=a2
0
R.(2.59)
Due o adhesion, he in e ac ing bodies adhe e while pulling (nega i e loads) un il a
c i ical o ce is eached. The de o ma ion pa ame e s a e summa ized in Figu e 2.17
and Tab. 2.2.
I he in e ac ion ene gy is negligible o o e y high loads (F > 103πwR), he esul s
o JKR and DMT models educe o he equa ions gi en by he He z model.
As men ioned abo e, bo h he JKR and he DMT model a e alid o di e en limi s o
ma e ial pa ame e s. Fo quan i ica ion o he alidi y o he pa icula model, Tabo
in oduced ” he Tabo pa ame e ” which is de ined by he a io be ween neck heigh
CHAPTER 2. THEORY AND STATUS OF THE FIELD 66
Table 2.2: Exp essions o con ac pa ame e s o di e en con ac mechanic models.
Adap ed om Re . [128].
He z JKR DMT
a3FR
K
R
KF+ 3πRw +p6πRwF + (3πRw)2F R
K+2πwR2
K
δa2
R=F2
K2R1/3a2
R−q8πaw
3K
a2
R=(F+2πRw)2
K2R1/3
σ3Ka
2πR p1− 2/a23Ka
2πR p1− 2/a2−q3Kw
2πa
1
√1− 2/a2
3Ka
2πR p1− 2/a2
Fadh 0−3
2πwR −2πwR
a c i ical de o ma ion due o adhesion and he ange o su ace o ces z0[146]
µT=16Rw2
9K2z3
01/3
.(2.60)
Fo µT<< 1, he DMT model is alid and o µT>> 1JKR heo y applies.
Maugis in oduced a mo e gene al heo y, which desc ibes he ansi ion ange be ween
he JKR and he DMT model and applies o all ma e ials om la ge ha d sphe es wi h
high su ace ene gy o small so bodies wi h low su ace ene gies. The Maugis heo y
desc ibes in e ac ions by a Dugdale model and esul s in exp essions o he con ac
pa ame e s as a unc ion o he so-called ”Maugis pa ame e ” (µM≈1.16µT). Fo
analy ic exp essions o he con ac pa ame e s, he eade is e e ed o Re . [127, 147].
Figu e 2.18 shows an o e iew o he a ailabili y o he p esen ed con ac mechanic
models.
A gene al exp ession o he con ac pa ame e s o wo axisymme ic elas ic bodies (i.e.
sphe e, pa abola, o cone) was gi en by Sneddon’s solu ion [127]. The eade should
no ice ha he con ac adius mus be known o hese exp essions. Also, one can show
o any punch ha he load displacemen can be w i en in he o m
F(δ) = αδn,(2.61)
wi h αincluding ma e ial pa ame e s and ndependen on he geome y (n= 1 o la
cylinde s, n= 2 o cones, n= 1.5 o pa aboloids i.e. sphe es) [128].
The exp essions o he s ess dis ibu ions p esen ed abo e (see Tab. 2.2) ha e limi a-
ions in hei phyical meanings, since he s esses in he desc ip ions a e in ini e a he
edge o con ac . This unphysical si ua ion can be esol ed using addi ional pa ame e s.
One can show ha he peak s ess can only be in he o de o he elas ic modulus o
CHAPTER 2. THEORY AND STATUS OF THE FIELD 67
A
B
C
Figu e 2.17: Con ac mechanics o elas ic bodies: 2.17A Con ac adius as a unc ion
o applied load, 2.17B De o ma ion as a unc ion o applied load o a so sphe e
(R= 10 µm,E= 1 MPa,w= 10 mJ/m2) p essed agains a ha d subs a e (do ed
lines show he hys e esis cha ac e o he JKR heo y). 2.17C S ess in he con ac
zone o a so sphe e o an applied load o F= 1 µN(do ed lines show he con ac
adius).
CHAPTER 2. THEORY AND STATUS OF THE FIELD 68
Figu e 2.18: A ailabili y o con ac mechanic models ( ep oduced om [148]
c
Else ie )
so ma e ials o he p edic ed VdW s ess o he in e ace.
Abo e, only o al linea elas ic de o ma ions we e ea ed. Fo inden a ions whe e plas-
ic de o ma ion o iscoelas ic phenomena occu he si ua ion is e en mo e complex
due o nonlinea beha io . App oaches o model hese con ac p oblems we e de el-
oped o example by Oli e and Pha [149]. Also, he e ogenei ies and oughness a e
neglec ed in he con inuum elas ic heo ies desc ibed abo e and should be aken in o
accoun o a ull ealis ic desc ip ion [150, 151].
CHAPTER 2. THEORY AND STATUS OF THE FIELD 69
Table 2.3: Expe imen al me hods o s udy esponsi e laye s, FTIR: Fou ie ans-
o m in a ed spec oscopy, QMB: Qua z c ys al mic o balance, SFA: Su ace o ce
appa a us, AFM: A omic o ce mic oscope, JKR: JKR appa a us
p ope ies me hods
chemical s uc u e FTIR, QMB, spec oscopy
hickness and densi y sca e ing echniques, ellipsome y, e lec ome y
spec oscopy, mic oscopy, SFA, AFM
su ace in e ac ions and mechanics SFA, AFM, JKR, mic oscopy
2.4 Expe imen al Me hods: A omic Fo ce and Op i-
cal Mic oscopy
Fo cha ac e iza ion and unde s anding o esponsi e su aces expe imen al echniques
a e necessa y. No el scanning p obe mic oscopy app oaches and op ical me hods can
gi e insigh s in o he beha io o su aces and in e aces [125]. Exempla y expe imen al
app oaches o s udy he chemical s uc u e, he hickness and densi y o esponsi e PE
su ace, as well as su ace in e ac ions and mechanical p ope ies a e summa ized in
Table 2.3 [1, 17]. These me hods a e accomplished by new heo e ical app oaches
and modeling echniques. This sec ion ocus on he used echniques in his hesis, in
pa icula a omic o ce and op ical mic oscopy. The discussion is o ien ed on [124, 125,
24, 126] and he ci ed li e a u e.
2.4.1 A omic Fo ce Mic oscopy (AFM)
Se e al cha ac e iza ion me hods a e known o s udy he esponse o sma coa ings
(Table 2.3). In his hesis, he ocus is se on changes o in e ac ions and mechanical
p ope ies o such sys ems on he colloidal scale. One o he mos sui able echniques
o su ace cha ac e iza ion in his egime is a omic o ce mic oscopy (AFM) [152].
Complemen a y me hods can be e.g. he su ace o ce appa a us [153, 154], he JRK
appa a us [155], o op ical o magne ic weeze s [156].
The AFM was in en ed by Binnig e al. in he 1980s [157] on he basis o he scan-
ning unneling mic oscope. Nowadays, he AFM has many ields o applica ions [158].
Besides he o iginal in en ion o imaging su ace opog aphies, he AFM allows o
de ec ing su ace and in e acial o ces, molecula in e ac ions and cha ac e iza ion o
he mechanical and he elec ical p ope ies o he su ace o he s udied ma e ial, jus
o name a ew.

CHAPTER 2. THEORY AND STATUS OF THE FIELD 70
Figu e 2.19: Wo king p inciple o an AFM
The wo king p inciple o an AFM is based on in e ac ions be ween he sample and
a p obe as a unc ion o hei dis ance. The p obe is commonly a can ile e which
de lec s owa ds o away om he su ace depending on a ac i e o epulsi e o ces.
The de lec ion can be de ec ed a high p ecision using se e al me hods. The mos com-
mon de ec ion me hod is he op ical le e app oach whe e a lase beam is ocused on
he backside o he can ile e and is e lec ed o a posi ion-sensi i e pho odiode (Fig-
u e 2.19). The posi ion-sensi i i y is achie ed by subdi ision o he de ec o ( ypically
qua e ized), which esul s in di e en in ensi ies on he indi idual a eas and inaly in
a cu en signal. The cu en can be ans o med in o he equi ed in o ma ion, in pa -
icula heigh changes ( hese can be u he con e ed o in e ac ion o ces, ha dness,
and oughness.)
The ac ing o ce can be calcula ed om he de lec ion o he can ile e by Hooks law
F(δc) = kcδc,(2.62)
whe e kcis he sp ing cons an and δc he de lec ion o he can ile e .
The ela i e posi ion o can ile e and sample is con olled by piezoelec ic elemen s
wi h a p ecession o 0.1 nm in x-, y-, and z- di ec ion. Typical can ile e s a e made om
CHAPTER 2. THEORY AND STATUS OF THE FIELD 71
silicon o silicon ni id and ha e a sp ing cons an in he o de o (0.001 −100) N/m.
Fo enhancemen o he e lec i i y o he can ile e , he backside o he can ile e can
be coa ed wi h a me al.
The ad an ages o an AFM a e i s high spa ial esolu ion on he nm scale (de e mined
by he con olu ion o he ip and he sample), high sensi i i y owa ds o ces in he
ange om pN up o some µN, and a esolu ion o de o ma ions smalle han 1 nm
(de e mined by he sp ing cons an o he can ile e ). These p os and he abili y o
s udy nea ly any kind o solid (o liquid) in e ace in a ious en i onmen s in a big em-
pe a u e ange ha e made he AFM one o he mos popula ools in su ace science.
Also, o he su ace p ope ies can bes s udied, as o example elec ical p ope ies by
con oling an elec ic po en ial applied o he can ile e . Fo ins ance la e al elec ic
p ope ies a e impo an in he semiconduc o and ha d disc indus y [159].
D awbacks o he AFM a e ha he echnique is ela i ely slow and limi ed o su ace
( a he han bulk) p ope ies. Addi ionally, he ope a ing dis ances a e limi ed by he
used piezos ( ypically in he ange o 10 µm o z-, and 100 µmin x- and y- di ec ion).
Imaging AFM
Fo imaging, ( ypically) sha p ip can ile e s a e scanned in x- and y- di ec ion o e he
sample subs a e. Th ee main ope a ion modes can be dis inguished: 1) he con ac
mode, 2) he noncon ac mode, and 3) he apping mode. In con ac mode, in e ac ion
o ces a e de ec ed while he can ile e ip emains in con ac wi h he sample du ing
scanning. The esul ing de lec ion (cons an heigh ) o he applied o ce o keep he
de lec ion cons an (cons a o ce), a e used as he signal. Using a eedback loop he
signal can be di ec ly con e ed in o a opog aphic image. The noncon ac and he
apping mode a e dynamic modes. He e he can ile e is oscilla ed nea i s esonance
equency and shi s o ampli ude and equency a e de ec ed. In case o he noncon ac
mode, shi s o he esonance equency a e de ec ed while mo ing he can ile e abo e
he su ace (no con ac ). The apping mode combines bene i s o bo h, he con ac
and non-con ac mode, by oscilla ing he can ile e nea i s esonance equency, while
allowing o small impac s o he can ile e ip in o he sample.
The esul ing image o hese modes is ma hema ically a con olu ion o he sample and
he p obe. As a esul he spa ial esolu ion is limi ed by he geome y o can ile e
ip11. An o e iew o he di e en imaging modes is gi en in Re . [158, 160, 161].
11Addi ional ac o s a e ex e nal and in e nal ib a ions and he damping quali y o he can ile e .
CHAPTER 2. THEORY AND STATUS OF THE FIELD 72
Fo ce Spec oscopy
Besides imaging, he AFM can be used o di ec o ce measu emen s [128, 152]. Fo
his, he can ile e is d i en in z- di ec ion owa ds o away om he su ace. The
can ile e de lec ion δcis eco ded as a unc ion o he piezo hub Z. This ou come can
be ans o med in o a o ce e sus dis ance (FD) cu e (o en named o ce-sepa a ion
o o ce-inden a ion cu e, depending on he expe imen ). Fo ha pu pose he ol age
o he pho odiode mus be ela ed o he o ce ac ing on he can ile e . I no a i ac s
occu s (e.g. due o e y la ge can ile e de lec ions), he de lec ion o he can ile e is
linea p opo ional o he ol age o he pho odiode V
δc=SV, (2.63)
whe e Sis he so-called ”in e ed op ical le e sensi i i y” (In OLS). I he sp ing
cons an o he can ile e kcis known p ecisely12 ( om calib a ion measu emen s, see
below), he de lec ion can be ans o med in o he ac ing o ce using Hooks law (eq.
2.62)
F(Z) = kcSV. (2.64)
The sepa a ion o a can ile e om he su ace Dis ela ed o he mo emen o he
z-piezo Zas
D=Z−(δC+δS),(2.65)
whe e δcis he can ile e de lec ion and δS he de o ma ion o he sample su ace. FD
cu es e lec he con ibu ions o su ace in e ac ions and Hooks law o he can ile e .
A schema ic example o a FD cu e is shown in Figu e 2.20.
When he can ile e is a away om he su ace, no in e ac ions occu e and can ile e
de lec ion is ze o. This pa o he FD cu e is called ”baseline”.
I he can ile e comes close o he su ace, he can ile e will s a o bend due o
su ace o ces. In case o a ac i e o ces, he can ile e will bend owa ds he su ace
and jump in o con ac (j c) when he g adien o he a ac i e o ces o e comes he
sp ing cons an o he can ile e . When he su ace o ces a e epulsi e (e.g. due o
elec os a ic di use laye oces, Ch. 2.3.3) he can ile e s a s o bend away om he
su ace which esul s in an inc ease o he de ec ed o ce.
I he can ile e mo emen is sus ained, he can ile e will de lec as desc ibed by Eq.
2.62 in combina ion wi h he de o ma ion o he sample (Tab. 2.2). In case o a ha d
subs a e (s i ness o he can ile e is much smalle han he s i ness o he subs a e),
12Manu ac u e alues a e ypically no ealible, see below o se e al calib a ion me hods
CHAPTER 2. THEORY AND STATUS OF THE FIELD 73
his esul s in he cons an complian egion, whe e p obe and sample su ace mo e
in pa allel. A a ce ain poin , he piezo mo emen is u ned back and he can ile e
e ac s. T ace and e ace in con ac a e named as con ac pa , con ain in o ma ion
on he mechanics o he sample. They can be desc ibed by con ac mechanical models
(Ch. 2.3.6).
In case o a ac i e o ces (adhesion be ween he sample and he p obe), he can ile e
will s ay in con ac un il he es o ing o ce o he can ile e o e comes he adhesion
o ce Fadh and he can ile e jumps ou o con ac (joc) (Fo exp essions o Fadh see
Tab. 2.2). The included a ea be ween ace and e ace o he FD cu e con ains
in o ma ion on he wo k o adhesion (adhesion hys e esis).
A B
Figu e 2.20: Fo ce dis ance cu e: 2.20A Can ile e mo emen , 2.20B De ec ed aw
da a, op (schema ic o ha d ip in e ac ing wi h a ha d subs a e) con e ed o a o ce
dis ance cu e, bo om.
The p esen ed FD cu e (Figu e 2.20) is jus a simpli ied example. Fo comple e in e -
p e a ion o he expe imen ally de ec ed FD cu es, including all su ace and molecula
in e ac ions, mechanical p ope ies (as in oduced in Ch. 2.3) and hyd odynamic e -
ec s o he sample, he eade is e e ed o Re . [128, 152]. In hese e iews also many
CHAPTER 2. THEORY AND STATUS OF THE FIELD 80
wi h I1and I2 he in ensi ies o he e lec ed ligh o he subs a e and he sample,
h(x) he local heigh o he specimen, k= 2πn/λ he wa e numbe o he ligh and δ
accoun ing o possible phase shi s.
Recons uc ion o he specimen is possible by he use o an a ccos- a o o Eq. 2.74
ha can be adop ed s epwise o he in e e ence pa e n. Fo ha pu pose, a ough
knowledge o he sample geome y is needed, in o de o conside he igh cu a u e
o he objec . Fo absolu e dis ance measu emen s, a ce ain e e ence poin mus be
known. Wi hou his knowledge, he absolu e dis ance pe pendicula o he su ace
can onloy be measu ed wi h wo-colo RICM [179].
Figu e 2.23: P inciple o e lec ion in e e ence con as mic oscopy (RICM): I0inci-
den ligh , I1 e lec ed ligh om he subs a e, I2 e lec ed ligh om he sample and
in e e ence pa e n (o a glass sphe e) on he de ec o .

CHAPTER 2. THEORY AND STATUS OF THE FIELD 81
2.5 Re e ences
[1] Knoll. Func ional Polyme Films. Vol. 1. Wiley-VCH. Weinheim, Ge many,
2011.
[2] T. P. Russell. “Su ace- esponsi e ma e ials”. In: Science 297.5583 (2002), pp. 964–
967.
[3] A. Sido enko e al. “Swi ching o polyme b ushes”. In: Langmui 15.24 (1999),
pp. 8349–8355.
[4] K. Glinel e al. “Responsi e polyelec oly e mul ilaye s”. In: Colloids and Su -
aces a-Physicochemical and Enginee ing Aspec s 303.1-2 (2007), pp. 3–13.
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CHAPTER 3. SOFT COLLOIDAL PROBE AFM 97
Abs ac
We p esen a me hod based on colloidal p obe a omic o ce mic oscopy (AFM) o mea-
su e adhesion ene gies and o s udy o he con ac phenomena o su aces. The me hod
employs an elas ome ic colloidal p obe, ende ing he con ac a ea be ween p obe and
sample much la ge as compa ed o s anda d a omic o ce mic oscopy echniques. The
echnique allows us o de e mine he con ac a ea ia mic oin e e ome y and measu e
he applied o ces a he same ime. The adhesion p ope ies can hen be accessed by
using he Johnson-Kendall-Robe s (JKR) app oach, i.e. measu ing (a) he con ac
a ea as a unc ion o applied load, and (b) he elas ic pa ame e s and he he mo-
dynamic wo k o adhesion. We es his me hod in ambien condi ions as well as in
aqueous media on well-known su ace chemis ies, and can clea ly cha ac e ize he con-
ibu ions o capilla y in ai , hyd a ion o ces and hyd ophobic in e ac ions in wa e .
This no el me hod p o ides a means o s udy he con ac beha io o so colloids and
enhanced sensi i i y o adhesion measu emen s.
3.1 In oduc ion
Adhesion and con ac phenomena a e impo an in many b anches o na u e and
echnology. Two cen u ies o esea ch ha e p o en hei signi icance in ields such
as nano(bio) echnology [1, 2, 3] and biophysics [4, 5]. Fo example, adhesion o ces
de e mine cell di e en ia ion [6] and allow liza ds o climb shee walls [7, 8]. Adhesion
echnology is i al in coa ings, composi e ma e ials [9, 10] o adhesi es [11]. The e
a e s ill many open ques ions on adhesion and con ac phenomena o so ma e sys-
ems. Cu en esea ch ocuses on he beha io o (bio)polyme s in wa e [12, 13, 14],
biosys ems ha make use o a ious adhesion s a egies on mul iple leng h scales [4]
o dynamic phenomena like ea angemen o polyme s inside he con ac a ea [15, 16]
o swi chable polyme b ushes ha change hei adhesion p ope ies by changing hei
en i onmen al condi ions [17]. To ackle such challenges se e al me hods sui able o
di e en leng h scales we e de eloped [18, 19, 20]. Wi h ega d o he size o con ac
a eas ha a e accessible, exis ing me hods can be g ouped in o mac o- and mic o-
scalecon ac me hods. The e o e, de elopmen s in adhesion measu emen me hods
allowed he s udy o mac o- and mic oscale-con ac phenomena: mac o-scale con ac s
a e cha ac e ized using Peel and o sion es s [20, 21, 22] and we ing me hods like
con ac -angle measu emen s [23, 24]. Fo ul a- hin ilms, he su ace o ce appa a us
(SFA) [25, 26, 27] p o ides an unpa alleled sensi i i y and e ical esolu ion on he
CHAPTER 3. SOFT COLLOIDAL PROBE AFM 98
nanome e-scale o mac o-scale con ac s. The so-called JKR appa a us akes ad an-
age o he ac ha he con ac a ea o la ge elas ome ic lenses can be modeled using
he Johnson-Kendall-Robe s heo y [28]. He e, adhesion ene gies a e de i ed using
he dependence o con ac a ea on he applied load. This me hod has been success ully
applied h ough he las yea s, o example as desc ibed in Re . [20] and [29, 30, 31,
32].
The ad an age o mac o-scale me hods is he well-de ined con ac a ea. Howe e , hese
me hods a e limi ed o smoo h and chemically homogenous samples o e a ew hund ed
µm2. On he mic o- and nanoscale he esolu ion o an a omic o ce mic oscope (AFM)
[33] is equi ed in o de o s udy su ace in e ac ions. [18] He e, su ace in e ac ions a e
measu ed by o ce-dis ance measu emen s, [34] whe e a sha p AFM ip ( ypical adius
o cu a u e in he ange o 5−20 nm) is b ough in o con ac wi h he sample. In
his mode usually he pull-o o ce o he AFM p obe om he sample su ace is used
as a measu e o he su ace-p obe in e ac ions. While his echnique allows access o
ex emely small con ac a eas, he con ac a ea is a he illde ined and canno be inde-
penden ly de e mined. The eason is ha he shape o AFM ips canno be accu a ely
con olled in he manu ac u ing p ocess o e en du ing measu emen and he e o e,
AFM ips do no sa is y he demand o a well-de ined con ac geome y. A majo
s ep owa ds sol ing his p oblem was he in oduc ion o he colloidal p obe-AFM
echnique [35] by Ducke e al. [36] and Bu [37] in he 1990s. Colloidal pa icles o
se e al mic ome es in size a e a ached o AFM can ile e s. Typically silica sphe es o
plas ic beads wi h a diame e in he ange o 1−50 mm and wi h su ace oughnesses
o only a ew nanome es a e used [18, 35]. While he p obe geome y is well de ined as
compa ed o s anda d AFM ips, he con ac adii wi h ha d subs a es a e s ill in he
o de o 100 nm and hus ha d o de e mine in si u. Because o ha majo d awback,
one s ill has o ely on assump ions a he han di ec measu emen o he con ac
a ea which is p oblema ic o de e mining he wo k o adhesion. In he las yea s he
colloidal p obe echnique was ex ended o measu e in e ac ion o ces o o desc ibe he
con ac beha io be ween o he kinds o p obes, o example segmen s o hai s [38] o
so p obes like d ople s [39, 40, 41, 42] o bubbles [43].
In his pape we desc ibe a no el echnique combining he ad an ages o he JKR
me hod wi h he colloidal p obe AFM app oach. We modi y he colloidal p obe ech-
nique o ob ain a la ge con ac a ea be ween p obe and sample by using so colloidal
pa icles, made o c oss-linked polydime hylsiloxane (PDMS). The elas ic p ope ies,
he size o he p obe and hus he size o he con ac a ea can be con olled by a ying
he p epa a ion me hodology o he so p obes. Unde sui able condi ions he con ac
CHAPTER 3. SOFT COLLOIDAL PROBE AFM 99
a eas a e su icien ly la ge o allow in si u measu emen using mic oin e e ome y [44,
45]. Consequen ly, he adhesion p ope ies o he sys em can be accessed by using he
JKR app oach.
3.2 Expe imen al
Ma e ials and me hods
The ins umen al se up elies on a combina ion o in e e ence mic oscopy and AFM
as ske ched in Figu e 3.1 and he use o no el p obe pa icles. In he ollowing, we
summa ize he p obe p epa a ion and moun ing p ocedu e, can ile e calib a ion, as
well as echnical de ails o he se up.
Fab ica ion and cha ac e iza ion o so colloidal p obes (SCPs)
The so p obes we e p epa ed ia c oss-linking d ople s o he p ecu so polyme in
solu ion. PDMS (Sylga d 184 ki ) was pu chased om Dow Co ning, USA. Fi s he
p epolyme was mixed wi h he cu ing agen using a 10 : 3 a io. Then, a Milli-Q wa-
e dispe sion con aining 5 w % PDMS p ecu so and 0.1 w % sodium dodecyl sul a e
(CAS numbe 151-21-3, Sigma-Ald ich, Ge many) was p epa ed. A e cu ing o h ee
days a oom empe a u e, he c oss-linked PDMS d ople s we e ex ac ed by eeze-
d ying. The esul ing pa icles we e cha ac e ized wi h an in e ed op ical mic oscope
(Axio e 200, Zeiss, Ge many) o de e mine pa icle sizes. Using AFM o ce-dis ance
measu emen s (Nanowiza d I, JPK Ins umen s AG, Ge many) he Young’s modu-
lus was de e mined as well. The mean diame e o he pa icles was in a ange o
10 o 30 µmand he co esponding Young’s modulus in he o de o 1 MPa.
Figu e 3.1: Schema ic o he expe imen al se up: Combina ion o AFM and op ics.
CHAPTER 3. SOFT COLLOIDAL PROBE AFM 100
Moun ing he p obes and calib a ion
The colloidal pa icles we e a ached wi h epoxy esin (UHU schnell es , Ge many)
on p e-calib a ed AFM can ile e s (7−28 Nm1, ipples NSC 12, Mic omash, Es onia)
using a mic omanipula o (MP-285, Shu e Ins umen , USA). The o ce cons an was
de ec ed wi h he he mal noise me hod, in oduced by Hu e and Bechhoe e [46]. A
ypical PDMS pa icle a ached o a can ile e is shown in Figu e 3.2. Delibe a ely,
we es ablished a la ge con ac a ea be ween can ile e and pa icle, such ha du ing
measu emen , he pa icle de o ma ion ook place mainly a he subs a e-p obe in e -
ace (see Figu e 3.3A). A e a achmen , he SCP was washed in Milli-Q wa e and
d ied by a s eam o ni ogen. A e wa ds, he SCP was ea ed o 40 s in 1 mba
ai plasma a 0.1 kW in ensi y (PDC-32 G plasma cleane , Ha ick, USA) in o de o
emo e su ace impu i ies and o p o ide a well-de ined silica-like laye on he SCP
su ace. Unde hose condi ions he hickness o he oxide laye is on he nanoscale
[47]. Thus, he elas ic p ope ies o he p obe a e no signi ican ly a ec ed by his
p ocess.
A B
Figu e 3.2: A ached PDMS pa icle on can ile e : 3.2A ligh mic oscopy image and
3.2B REM image.
Fo ce spec oscopy
A comme cial AFM (Nanowiza d I, JPK Ins umen s AG, Ge many) was used o all
AFM measu emen s. SCPs we e moun ed in o he AFM se up and he op ical le e
sensi i i y was de ec ed (see Resul s and discussion sec ion: Bounda y condi ions, cal-
ib a ion and modeling o he SCP). The maximum applied o ce was be ween 1600 nN
and 2500 nN. Fo he JKR app oach, he load was changed s epwise in in e als o
CHAPTER 3. SOFT COLLOIDAL PROBE AFM 101
A B
Figu e 3.3: 3.3A Schema ic o he con ac beha io o he sys ems, p obe-subs a e
and p obe-can ile e ; 3.3B ske ch illus a ing he con ac pa ame e s: he do ed line
ep esen s he unde o med p obe, he solid line ep esen s he de o med p obe.
a ound 200 nN. The p esen ed measu emen s show he mean alue o ou di e en de-
ec ion posi ions o he p obe on he subs a e. The o ce-dis ance cu es we e eco ded
using he ollowing pa ame e s: he speed o he piezo ac ua o was se o 8µms−1.
The o ce-dis ance cu es we e measu ed on di e en spo s using he o ce-mapping
mode o he AFM. Measu emen s we e unde aken on a leas 64 spo s on a 100 µm2
g id on he subs a e.
Re lec ion in e e ence con as mic oscopy
We used e lec ion in e e ence con as mic oscopy [48, 49] (RICM) o e alua e he
con ac a ea o he SCPs wi h a ha d subs a e ( unc ionalized glass su ace) in si u.
Du ing RICM, he sample was illumina ed wi h monoch oma ic ligh in e lec ion ge-
ome y. Ligh was e lec ed by he subs a e and he SCP in e ace. Due o phase shi
and he pa h leng h di e ence be ween he e lec ed beams an in e e ence pa e n sim-
ila o New on ings can be obse ed. This in e e ence pa e n p o ides in o ma ion
abou he local dis ance be ween he SCP and he subs a e, as well as he con ac
a ea. To enhance he in e e ence pa e n we used he an i lex echnique in oduced by
Ploem [50]. Fo illumina ion we used a Hg- apo lamp wi h wo di e en monoch o-
ma o s (481 nm and 546 nm). A Zeiss An i lex 63 X NO 1.25 oil-imme sion objec i e,
addi ional pola ize s o a oid in e nal e lec ions and a Zeiss AxiocamHRm came a
we e used o image he RICM pa e ns. De ails o he calib a ion o he RICM se up
and he e alua ion p ocess o he con ac a ea a e summa ized in Ch. 3.A and u he

CHAPTER 3. SOFT COLLOIDAL PROBE AFM 102
de ails o he se up a e epo ed in Re .[44, 45, 51] and [52].
Tes su ace p epa a ion
To es he me hod, we s udied samples wi h known su ace chemis y. He e, sym-
me ically unc ionalized su aces (SCP-subs a e), i.e. hyd ophilic-hyd ophilic and
hyd ophobic-hyd ophobic sys ems, we e s udied. The su aces we e modi ied ia silani-
sa ion agen s by gas phase deposi ion. Hyd ophilic su aces we e p epa ed using
[hyd oxy(polye hyleneoxy)p opyl] ie hoxysilane (8-12EO), 50% e hanol (ABCR, Ge -
many); hyd ophobic su aces we e p epa ed using (hep adeca luo o-1,1,2,2- e ahyd odecyl)
dime hylchlo osilane (ABCR, Ge many).
3.3 Resul s and Discussion
Bounda y condi ions, calib a ion and modeling o he SCP
The de o ma ion o he SCP can only be obse ed a he side o he p obe acing he
subs a e. The e o e, he main de o ma ion o he so p obe should be loca ed in he
con ac egime o p obe and su ace. This can be ensu ed by ende ing he con ac a ea
o pa icle and can ile e much la ge han he con ac a ea o p obe and su ace (see
Figu e 3.3A). Hence we used SCPs whe e he con ac be ween colloidal pa icle and
can ile e was adequa e (la ge enough) a e he a achmen . In o de o pe o m AFM
o ce-dis ance measu emen s he sp ing cons an o he can ile e as well as i s in e ed
op ical le e sensi i i y (In OLS) a e equi ed. The In OLS is he p opo ionali y
cons an be ween pho odiode signal and he can ile e de lec ion. Measu ing bo h
pa ame e s allows calcula ion o he In OLS. In he case o a SCP-modi ied can ile e
his leads o some special challenges: Usually, he can ile e de lec ion is de e mined
by p essing he can ile e on a ha d, non-de o mable subs a e. In his case he piezo
displacemen is iden ical o he can ile e de lec ion and he In OLS can be di ec ly
ead om o ce-dis ance cu es eco ded on ha d subs a es. This is no possible wi h
an SCP a ached o he can ile e . The e o e, we de eloped wo al e na i e app oaches
o de e mine In OLS: o measu emen s in ai , we used a noncon ac app oach o
de e mine In OLS [53]. We use can ile e s o which he sp ing cons an has been
de e mined ex si u and ca y ou a sp ing cons an de e mina ion using he he mal
noise me hod in si u. As his me hod equi es he In OLS as an inpu pa ame e , i
can be used o de i e i by adjus ing he In OLS un il i ma ches he known sp ing
cons an (see Ch. 3.A). In liquid he he mal noise me hod canno be used due o
CHAPTER 3. SOFT COLLOIDAL PROBE AFM 103
high damping [18]. In his case, we de ec ed he op ical le e sensi i i y by analysis
o he slope o a o ce-dis ance cu e in con ac egion, while p essing he apex o he
can ile e agains a sha p edge.
In o de o de i e adhesion ene gies he sys em has o be modelled using he p ope
con ac -mechanic heo y [54]. The i s analy ical desc ip ion o con ac be ween wo
iso opic, homogeneous, linea elas ic bodies, bu wi hou adhesion con ibu ion, was
gi en by He z. [55] Rega ding he adhesion con ibu ion he e a e se e al heo ies
which apply o ce ain limi s o con ac beha io . The espec i e limi ing cases a e
desc ibed by he elas ic and adhesi e p ope ies o he sys em [54]. Con ac pa ame e s
like con ac adius, de o ma ion, p essu e dis ibu ion, e c. a e unc ions o load, elas ic
pa ame e s o he sys em and he adhesion in e ac ion. The wo mos common heo ies
we e de eloped by Johnson, Kendall and Robe s [28] (JKR heo y) and De jaguin,
Mulle and Topo o [56] (DMT heo y). Tabo [57] showed ha i is possible o
sepa a e ( o quan i y) he di e en limi s o con ac beha io wi h a pa ame e µT
( espec i ely Maugis [58] λ∝µT) by compa ing he elas ic de o ma ion caused by he
su ace in e ac ions wi h he ange o su ace o ces:
µT=16Rw2
9K2z3
01/3
(3.1)
whe e Ris he e ec i e adius o cu a u e, Kis he e ec i e elas ic modulus o he
sys em, wis he he modynamic wo k o adhesion and z0is he equilib ium sepa a-
ion o he su aces (in e a omic equilib ium dis ance o solid-solid in e ac ions in he
Lenna d-Jones po en ial, ypically on he ange o 0.3 o 0.5 nm). Rand Ka e gi en
by:
1
R=1
R1
+1
R2
and 1
K=3
41−ν2
1
E1
+1−ν2
2
E2(3.2)
he e R1and R2a e he adii o cu a u e o he in e ac ing su aces, E1and E2a e
hei Young’s moduli, and ν1and ν2 hei Poisson a ios (Figu e 3.3B. In he case o
so solids, la ge adius o cu a u e and la ge adhesion ene gy (µT>5), he JKR
heo y is alid. Fo s i solids, small adius o cu a u e and weak ene gy o adhesion
(µT<5) he DMT heo y is alid [54].
To analyze ou da a we ha e o decide i s o all which heo y is sui able o desc ibe ou
sys em. We a e in e es ed in la , ha d su aces in e ac ing wi h he so p obes. Fo an
elas ome ic sphe e (R1,E1,ν1= 0.5) ouching such a su ace (R2→ ∞,E2>> E1),
he e ec i e adius o cu a u e R educes o R1and he e ec i e modulus o he sys em
Kequals 16/9E1(see Eq. 3.2). Wi h a p obe adius in he ange o R1= 10 µm, a
CHAPTER 3. SOFT COLLOIDAL PROBE AFM 104
Young’s modulus on he o de o E1= 1 MPa and a ypical he modynamic wo k o
adhesion in he ange o w= 10 mJm−2 he Tabo pa ame e (Eq. 3.1) lies in he
ange o µT>50. The e o e, we a e in he limi o he JKR heo y. Following he JKR
heo y he con ac adius be ween wo sphe es p essed oge he by a load Pis gi en
by:
a3=R
KP+ 3πRw +p6πRwP + (3πRw)2(3.3)
Adhesion measu emen s
JKR desc ibe he con ac a ea as a unc ion o load P, elas ic p ope ies K, and he ad-
hesion ene gy w:a= (P, K, w), see Eq. 3.3. In o de o ob ain he adhesion ene gy we
p ess he SCP agains he subs a e o choice, which can be done wi h subnanonew on
p ecision using he AFM eedback loop. Simul aneously, we eco d he adhesion a ea
by mic oin e e ome ic imaging. The da a a e collec ed a disc e e load- o ce in e als
o ∆P > 100 nN. Figu e 3.4 shows a ypical expe imen o a hyd ophilic unc ionalized
SCP agains a hyd ophilic ha d subs a e in wa e . The JKR i , as shown in Figu e
3.4B, was compu ed using Eq. 3.3, yielding he adhesion ene gy and he Young’s mod-
ulus as i pa ame e s. To c osscheck he Young’s modulus we de ec ed o ce-dis ance
cu es o SCPs on a ha d subs a e. The o ce-dis ance cu es we e ans o med in o
o ce-de o ma ion cu es o he so p obe by sub ac ing he e ec o he can ile e
de lec ion. Then we i ed he con ac egion o he o ce de o ma ion cu es wi h he
He z model [55]. Bo h moduli a e in he same ange ( a ia ion <25%). This is
in ag eemen wi h indings epo ed in li e a u e, e.g. Re . [59] To es he me hod
u he , we in es iga ed su aces wi h known su ace chemis y. Adhesion in e ac ion
o symme ically unc ionalized su aces, hyd ophilic p obe-hyd ophilic subs a e and
hyd ophobic p obe-hyd ophobic subs a e, was in es iga ed and compa ed o li e a u e
esul s.
Hyd ophilic in e ac ions
Fo he hyd ophilic p obe and he hyd ophilic subs a e in wa e we expec ela i ely
small adhesion o ces due o hyd ophilic in e ac ions [60]. The JKR app oach leads
o alues o wwa e = 1.8±0.3 mJm−2(Figu e 3.5A) using a pa icle wi h a adius o
R= 10.9µmcon ac wi h he hyd ophilic su ace. The Young’s modulus o he pa icle
de ec ed by he JKR i was E= 0.7±0.1 MPa. The alue o 1.8 mJm−2is a he de-
ec ion limi o adhesion ene gies o he SCP me hod a his s age, bu in a easonable
ange conside ing ha he hyd ophilic su ace migh be sligh ly con amina ed. Values
CHAPTER 3. SOFT COLLOIDAL PROBE AFM 105
A
B
C
Figu e 3.4: Analysis o he he modynamic wo k o adhesion wby ex ac ion o he
con ac adius a o a ying loads P. 3.4A Fo ce-dis ance cu e o a hyd ophilic so
colloidal p obe agains a hyd ophilic su ace (solid line ep esen s app oach cycle, do -
ed line ep esen s he e ac ion cycle, and dashed lines show eadings o he con ac
a ea as shown in 3.4B. 3.4B RICM images o he SCP allowed de e mina ion o he
con ac adius. 3.4C The plo o aagains P ollows he JKR p edic ions. The he mo-
dynamic wo k w is ex ac ed om he JKR i s (c oss-make s, X, deno e expe imen al
da a, black line deno es he JKR i ).
CHAPTER 3. SOFT COLLOIDAL PROBE AFM 112
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3.A Suppo ing In o ma ion
RICM
In o de o econs uc he heigh p o ile o he objec om he RICM images, h ee
di e en app oaches a e possible: The simple heo y (conside s ligh which en e s he
sample in di ec ion no mal o he plane o he subs a e), he ini e ape u e heo y
(co ec ion o ini e ape u e e ec s) and he non-local heo y (co ec ion o ini e
ape u e e ec s and co ec ions due o cu ed in e aces) [49]. To ge he in ensi y
dis ibu ion o e he dis ance om aw da a we ake he a e age o in ensi y p o iles
o e an angle ϕ, shown in Figu e 3.6A. Fo analysis o he in ensi y dis ibu ion we used
he simple heo y wi h co ec ion ac o s o ini e ape u e and geome y e ec s [52].
To ob ain he co ec ion ac o s, we imaged glass beads (Polysciences Inc., Wa ing on,
PA) on a glass su ace in RICM mode. We eco ded 10 glass beads wi h a diame e
in he ange o 30 −50 µmand ex ac ed he in ensi y p o ile, see Figu e 3.6B. Using
he p o iles, we econs uc ed he shape o he beads and compa ed i o he calcula ed
shapes (Rby measu ing hei size wi h ligh mic oscope), and de e mined he co ec ion
ac o s co esponding o ou expe imen al se up p esen ed in Figu e 3.6C.
Op ical Le e Sensi i i y
In o de o accu a ely de e mine he o ce om can ile e de lec ion he op ical le e
sensi i i y is equi ed. Howe e , since we a ached so p obes on he can ile e s,
we canno use he s anda d p ocedu e in o de o measu e he op ical le e sensi i i y,
i.e. o ce-dis ance measu emen s on a ha d subs a e o ob ain he can ile e de lec ion
om he z-piezo displacemen . He e we use he sp ing cons an o he can ile e , which
was measu ed be o e, in combina ion wi h he The mal Noise Me hod o de e mine he
op ical le e sensi i i y [53].
CHAPTER 3. SOFT COLLOIDAL PROBE AFM 116
A
B
C
Figu e 3.6: E alua ion o he RICM immages: 3.6A RICM image o a glass bead,
3.6B ex ac ed in ensi y p o ile, 3.6C econs uc ion o bead p o ile
CHAPTER 3. SOFT COLLOIDAL PROBE AFM 117
The de e mina ion p ocess is shown in he ollowing low cha :
1. De ec ion o sp ing cons an o can ile e (wi hou so p obe) ⇒kc
2. De ec ion o sensi i i y o can ile e wi h so p obe on o a ha d subs a e ⇒S0
3. The mal Noise Me hod wi h so p obe on can ile e ⇒k0
c
4. I ⇒k0
c6=kcchange sensi i i y and go back o 3.
I ⇒k0
c=kcsensi i i y o he cu en se up.
In liquid he The mal Noise Me hod canno 1be used due o high damping [18]. In his
case, we de ec he op ical le e sensi i i y by using he s anda d p ocedu e, i.e. o ce-
dis ance measu emen on a ha d subs a e, bu a oiding de o ma ion o he colloidal
p obe. This can be done by app oaching he e y ip o he can ile e apex on o a
sha p edge, no ouching he so colloidal p obe. Any s eep li hog aphic su ace can
be used as a sha p edge, he e we use a can ile e chip (CSC38, Îij-mash, Es onia) glued
on o a glass su ace.
Fo ce spec oscopy mode
In addi ion o he JKR app oach shown in he main ex , he so colloidal p obe se up
also allows o ob ain he adhesion om AFM o ce-dis ance cu es. Fo m o ce-dis ance
cu es as shown in Figu e 3.7 we de e mine he wo k o adhesion Wadh (a ea o he
o ce cu e unde he baseline [34]). Simul aneously we measu e he con ac adius a
o he adhesion a ea a maximum load ia RICM. The adhesion ene gy pe uni a ea
wcan hen be calcula ed acco ding o di iding Wadh by πa2. Fo s a is ics, we de ec
he o ce-dis ance cu es in mapping mode, de ining a 100 µm2g id on he subs a e
wi h a leas 64 da a poin s. A e wa ds, he o ce-displacemen measu emen s a e
done on each poin o he g id. Fo he hyd ophilic sys em in wa e we ound wwa e =
(0.9±0.1) mJ/m2, and in ai wai = (40 ±10) mJ/m2. Fo he hyd ophobic p obes in
wa e we ob ained wwa e = (45 ±10) mJ/m2and wai = (11 ±5) mJ/m2in ai . These
alues ag ee well wi h alues epo ed in he li e a u e. The capilla y o ce is a line
e ec , so in ai win uni s J/m2 ep esen s a e e ence alue.
1can jus app oxima ely used (included a e publica ion)

CHAPTER 3. SOFT COLLOIDAL PROBE AFM 118
Figu e 3.7: Analysis o he he modynamic wo k o adhesion: Collec o ce dis ance
cu e, e alua ing wo k o adhesion Wadh (g ay a ea) and measu ing simul aneously
he pa icle-su ace con ac a ea a maximum load by mic o in e e ome y (RICM).
4
Di ec Co ela ion be ween Local P essu e
and Fluo escence Ou pu in
Mechano esponsi e Polyelec oly e B ushes
Rep oduced by pe mission o John Wiley and Sons, Angewand e Chemie-In e na ional
Edi ion, 2011. 50(41): p. 9629-9632.
Copy igh c
(2011) WILEY-VCH Ve lag GmbH & Co. KGaA, Weinheim
Bunsow, J., E a h, J., Biesheu el, P. M., Fe y, A., Huck, W. T. S., Di ec Co ela ion
be ween Local P essu e and Fluo escence Ou pu in Mechano esponsi e Polyelec oly e
B ushes. Angewand e Chemie-In e na ional Edi ion, 2011. 50(41): p. 9629-9632.
119
CHAPTER 4. MECHANORESPONSIVE POLYELECTROLYTE BRUSHES 121
4.1 In oduc ion
In ecen yea s, he e has been huge p og ess in he de elopmen o s imuli- esponsi e
polyme ic ma e ials [1], and especially mechano esponsi e polyme s, which con e me-
chanical s imuli in o op ical, elec ical o chemical signals a e a pa icula ly a ac i e
class o ma e ials [2, 3, 4, 5]. An ul ima e goal o such ma e ials would be o emula e
he unique esponsi eness o human skin, which can de ec gen le ouches o a ound
1 kPa a a spa ial esolu ion o abou 40 µm[6].
He e, we in oduce a new concep o op ical o ce mapping based on mechano espon-
si e polyelec oly e b ushes, which in addi ion o hei esponse o o ce also espond
o changes in he chemical en i onmen [7]. Dense, s ong polyelec oly e b ushes a e
ha d o comp ess due o he inc ease o he osmo ic p essu e o he coun e -ions and he
excluded olume in e ac ions be ween he indi idual chains [8, 9]. Thus, hey a e no
mechanically esponsi e pe se, and o gene a e an op ical signal a ”mechanopho e” [10]
needs o be in oduced. P e iously, we used a pH-sensi i e dye o ac as a mechanosen-
si i e building block, whe e he dissocia ion cons an o he dye was a unc ion o b ush
comp ession [7]. Howe e , he dye was only in il a ed in o he b ush and no a co alen
pa o i . Fu he mo e, only quali a i e in o ma ion on he co ela ion be ween p es-
su e and op ical esponse was ob ained. The key ad ance in he p esen wo k is he
quan i a i e cha ac e iza ion o he mechano esponsi e p ope ies o polyelec oly e
b ushes unc ionalized by co alen a achmen o luo escen dye molecules. We ha e
de e mined a esponse unc ion I(p), which co ela es local luo escence in ensi y (I)
o local p essu e (p) and we ha e ound an excellen p essu e sensi i i y in he o de
o 10 kPa and a la e al esolu ion be e han 1µm.
4.2 Expe imen al
Full expe imen al de ails on polyme b ush o ma ion and cha ac e iza ion and de e -
mina ion o luo escen monome loading in b ushes as well as a de ailed desc ip ion
o so colloidal p obe expe imen s and JKR analysis is a ailable in he Suppo ing
In o ma ion sec ion 4.A.
CHAPTER 4. MECHANORESPONSIVE POLYELECTROLYTE BRUSHES 128
Acknowledgemen s
W.T.S.H. g a e ully acknowledges unding om he F ied ich Wilhelm Bessel Awa d o
he Humbold Founda ion. J.B. hanks he Ge man Resea ch Founda ion (Deu sche
Fo schungsgemeinscha , DFG) o unding. J.E. and A.F. g a e ully acknowledge i-
nancial suppo om he Deu sche Fo schungsgemeinscha (Fo sche g uppe 608: TP:
Fe 600/10-1). We hank Pe a Zippelius o help ul assis ance in ca ying ou some o
he expe imen s.
4.5 Re e ences
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CHAPTER 4. MECHANORESPONSIVE POLYELECTROLYTE BRUSHES 129
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CHAPTER 4. MECHANORESPONSIVE POLYELECTROLYTE BRUSHES 130
4.A Suppo ing In o ma ion
Expe imen al
Ma e ials
METAC (80 w .%in wa e ), AEMA, HEMA, CuB , CuCl, CuCl2, CuB 2, 2,2’-bipy idyl
(bipy), ie hylamine, 5(6)-ca boxy luo escein N-hyd oxysuccinimide es e (CF-NHS)
and sodium dodecyl sul a e we e pu chased om Sigma Ald ich and used as ecei ed
unless o he wise s a ed. NaCl and NaClO4we e om G uessing (Ge many). P io
o polyme isa ion, METAC and HEMA we e ac i a ed by passing o e a neu al alu-
mina column. T ie hylamine was dis illed om KOH and s o ed o e molecula sie e
(4 Å, Sigma Ald ich). CuB and CuCl we e s o ed unde acuum. High pu i y wa-
e o a esis ance o 18.2 MΩcm was ob ained om a Millipo e Syne gy sys em. The
ATRP ini ia o 2-b omo-2-me hylp opionic acid 3- ichlo osilanlyp opyl es e was syn-
hesised acco ding o Re . [21, 22]. Round co e slips (ø= 24 mm) we e pu chased
om VWR and cleaned by 10 min sonica ion in e hanol. 5(6)-ca boxy luo escein N-
hyd oxysuccinimide es e was s o ed a −20 ◦C. The PDMS p ecu so ki Sylga d 184
was ob ained om Dow Co ning (USA).
Ini ia o Immobilisa ion on Glass
Glass co e slips we e cleaned in ai plasma (Emi ech, model K1050X) o 10 min a a
powe o 100 W.50.4µL ie hylamine we e mixed wi h 30 mL d y oluene and 10 µL
o he ATRP ini ia o we e added unde shaking. The mix u e was ans e ed o
he pe i dish con aining he glass slides and ini ia o immobilisa ion p oceeded unde
gen le shaking (50 pm) o e nigh . The modi ied glass slides we e insed wi h oluene,
e hanol and wa e , d ied wi h ni ogen and baked in an o en a 150◦C o 3 o 4 hou s.
Syn hesis o Polyme B ushes
METAC (7 g, 30 mmol), AEMA (0.5 g, 3 mmol), bipy (214 mg, 1.4 mmol) and CuCl2
(3.6 mg, 0.03 mmol) we e dissol ed in a mix u e o wa e (2.4 mL) and isop opanol
(9 mL). The solu ion was degassed wi h N2 o 30 min. CuB (80 mg, 0.56 mmol) and
ini ia o modi ied glass co e slips we e placed in sepa a e Schlenk ubes and degassed
by e acua ing and lushing wi h N2in a leas h ee subsequen cycles. CuB was
dissol ed in he monome solu ion by sonica ion. The eac an mix u e was added o
he co e slips and kep a oom empe a u e unde N2 o 5 hou s. Samples we e
CHAPTER 4. MECHANORESPONSIVE POLYELECTROLYTE BRUSHES 131
insed wi h e hanol, wa e , and ace one; and sonica ed in wa e o 10 mins o emo e
non-co alen ly a ached polyme . Samples we e d ied wi h N2and kep unde N2un il
u he use.
A achmen o Ca boxy luo escein
CF-NHS was dissol ed in dime hylsul oxide a a concen a ion o 1 mg/mL. B ushes
on glass slides we e imme sed in 2 mL 0.1 M aqueous NaHCO3and 200 µlo he dye
s ock solu ion we e added unde shaking. Dye immobilisa ion was allowed o p oceed
in he da k o e nigh unde shaking (100 pm). Samples we e insed wi h wa e and
sonica ed o 10 min in 1 M NaCl and wa e , espec i ely, o emo e non-co alen ly
a ached dye.
Syn hesis o neu al P(HEMA-co-AEMA) b ushes
Hyd oxye hylme hac yla e (HEMA) was pu chased om Sigma Ald ich and ac i a ed
by passing o e neu al alumina. P(HEMA-co-AEMA) b ushes we e p epa ed om
a solu ion o HEMA (6 mL, 50 mmol), AEMA (0.9 g, 5 mmol), bipy (163 mg, 2
mmol) and CuB 2 (24 mg, 0.1 mmol) in wa e (6.5 mL). A e degassing wi h ni ogen
o 30 min, he monome solu ion was added o degassed CuCl (37 mg, 0.35 mmol)
in a Schlenk ube. The eac an mix u e was added o he co e slips and kep a
oom empe a u e unde N2 o 5 hou s. Samples we e insed wi h e hanol, wa e , and
ace one; and sonica ed in wa e o 10 mins o emo e nonco alen ly a ached polyme .
Samples we e d ied wi h N2and kep unde N2un il u he use.
Comp ession Expe imen s
Comp ession expe imen s we e ca ied ou wi h a combina ion o an AFM (MFP 3D
I,Asylum Resea ch, USA) and a CLSM (LSM710, Zeiss, Ge many). Using he SCP
echnique, we comp essed he polyelec oly e b ushes in he di ec ion no mal o he
su ace and eco ded he op ical esponse ia CLSM. Measu emen s we e pe o med in
a 0.1 ml liquid d ople . Samples we e s o ed in wa e o gua an ee ull hyd a ion o
he b ushes. A e measu emen s in 0.1 M NaClO4solu ion, samples we e egene a ed
by ex ensi e insing in 1 M NaCl and wa e .
AFM
PDMS beads wi h diame e s o 20 o 40 µmwe e p epa ed acco ding o Re . [11],
ans e ed o a polys y ene dish by dip-coa ing, and glued wi h an epoxy esin (UHU
CHAPTER 4. MECHANORESPONSIVE POLYELECTROLYTE BRUSHES 132
schnell es , Ge many) o p e-calib a ed can ile e s (728 N/m, NSC 12, ipless, noAl,
Mic omash, Es onia) using a mic omanipula o (MP-285, Shu e Ins umen , USA)
and an in e ed op ical mic oscope (Axio e 200, Zeiss, Ge many). Fo ce cons an s
o he can ile e s we e de e mined by he he mal noise me hod. Using AFM o cedis-
ance measu emen s and He z analysis (neglec ing adhesion and de o ma ion o he
b ush), he YoungâĂŹs Modulus o he bead was de e mined o be in he o de o
1 MPa. The SCP was washed wi h wa e , d ied in a s eam o ni ogen and moun ed
in o he AFM holde . P io o e e y measu emen , he op ical le e sensi i i y (IN-
VOLS) was de e mined ia a noncon ac app oach wi h an e o o he applied load
o abou 15 %. The SCP was p essed agains he subs a e wi h a de ined o ce using
he AFM eedback loop. Da a we e collec ed a disc e e load- o ce in e als o 500 nN
wi h a maximum o ce o 8µN. All da a a e a e aged alues o measu emen s on a
leas h ee di e en la e al posi ions on he subs a e.
CLSM
The CLSM was equipped wi h an EC ”Plan-Neo lua ” 20x/0.50 M27 objec i e. Images
we e acqui ed wi h a esolu ion o (0.104X0.104) µm2a a pinhole size o 1 ai y uni
(= 4.4µm). Fluo escence was exci ed a a wa eleng h o 488 nm and emission was
de ec ed om 492 o 625 nm. The ocus plane was se o he plane o maximum luo-
escence in ensi y. Fo P(METAC-co-AEMA) b ushes, he mas e gain (a measu e o
he powe applied o he pho ode ec o ) was se o 650 a a lase powe o 5%. Neu-
al b ushes showed a highe luo escence in ensi y and s ong bleaching which made
i necessa y o educe he lase powe o 0.5%. Images we e p ocessed wi h an ImageJ
mac o. The adial in ensi y dis ibu ion om he cen e o he comp ession zone o
he undis u bed backg ound was ex ac ed by a e aging he g ey alue o he images
o e an angle phi (see below).
Cha ac e iza ion o ca ionic and neu al b ushes
G ow h kine ics o ca ionic homo-and copolyme b ushes
G ow h kine ics o ca ionic homo-and copolyme b ushes: Figu e 4.5
Film hickness and luo escence in ensi y o ca ionic and neu al b ushes
Co ela ion o ilm hickness as a unc ion o sal concen a ion and luo escence in en-
si y o ca ionic and neu al b ushes see Figu e 4.6.
CHAPTER 4. MECHANORESPONSIVE POLYELECTROLYTE BRUSHES 133
Figu e 4.5: G ow h kine ics o PMETAC (black ) and P(METAC-co-AEMA) ( ed
) wi h an AEMA concen a ion o 10 mol −%in he eed. The d y ilm hickness d
inc eases linea ly wi h polyme isa ion ime. G ow h kine ics o homo- and copolyme
b ushes a e e y simila .

CHAPTER 4. MECHANORESPONSIVE POLYELECTROLYTE BRUSHES 134
A
B
Figu e 4.6: 4.6A Film hickness measu ed by AFM in liquid o P(METAC-co-AEMA)
(black ) and P(HEMA-co-AEMA) ( ed ◦) b ushes in wa e , NaCl solu ions and 0.1
M NaClO4solu ion a e he co alen a achmen o ca boxy luo escein. Values on
he le side e e o wa e and NaCl solu ions o a ious concen a ions; he alue on
he igh side was measu ed in 0.1 mol/Laqueous NaClO4. The hickness o ca ionic
b ushes depends s ongly on he sal concen a ion whe eas neu al b ushes show li le
esponse o he addi ion o sal . 4.6B Fluo escence in ensi y o uncomp essed b ushes
imme sed in wa e and sal solu ions. Ca ionic b ushes show a s ong dec ease o
luo escence in ensi y wi h inc easing sal concen a ion; he luo escence in ensi y o
neu al b ushes is much less a ec ed by he addi ion o sal .
CHAPTER 4. MECHANORESPONSIVE POLYELECTROLYTE BRUSHES 135
Appa en dye concen a ion
The appa en dye concen a ion in he b ushes was measu ed by UV- is spec oscopy
using he ollowing p ocedu e. Calib a ion was ealized by dissol ing 0.002−0.08 mmol/L
ca boxy luo escein in wa e . Spec a we e acqui ed in a wa eleng h egime om
400 −600 nm. The peak heigh a 480 nm was plo ed e sus he bulk concen a-
ion and he slope o a linea i o he da a was de e mined o be 8.2. Wi h Bee ’s
law 4.3
Eλ=−lg I1
I0
=λcd, (4.3)
whe e Eλis he ex inc ion, I1and I0a e he in ensi ies o ansmi ed and i adia ed
ligh , espec i ely, λis he mola abso b i i y, cis he dye concen a ion, and dis he
pa h leng h (he e: hickness o cu e e, 0.1 dm) i ollows ha λ= 82 dm2/mmpl.
A d ople o wa e was added o he su ace o glass co e slips co e ed wi h b ushes.
Samples we e sandwiched be ween wo PDMS slides and moun ed in a home-buil
holde wi h a hole (Ø≈1 cm) h ough which he ligh beam could pass. The maximum
in ensi y was de ec ed a 480 nm. The dye concen a ion was calcula ed om
capp =Eλ
λdb ush
,(4.4)
whe e capp is he appa en dye concen a ion in he b ush and db ush is he hickness o
he b ush in wa e .
pKa o ca boxy luo escein a ached o cha ged and neu al b ushes
The pKa o ca boxy luo escein co alen ly a ached o b ushes was measu ed wi h he
CLSM by de ec ing he luo escence in ensi y o b ushes in con ac wi h dilu ed HCl
and NaOH solu ions whose o al sal concen a ion was adjus ed o 10 mmol/Lby
addi ion o NaCl. Ti a ion cu es we e i ed wi h a sigmoidal i using Mic ocal
O igin 6.0. The in lec ion poin o he i is he pKa o he dye bound o he b ush.
(see Figu e 4.7)
Film hickness and luo escence in ensi y o ca ionic and neu al b ushes
Co ela ion o ilm hickness as a unc ion o sal concen a ion and luo escence in en-
si y o ca ionic and neu al b ushes see Figu e 4.6.
CHAPTER 4. MECHANORESPONSIVE POLYELECTROLYTE BRUSHES 136
A B
Figu e 4.7: Fluo escence in ensi y, no malized o maximum alue, o wo i a-
ion expe imen s on 4.7A ca ionic P(METAC-co-AEMA) (squa es) and 4.7B neu al
P(HEMA-co-AEMA) (ci cles)) b ushes as a unc ion o pH. S aigh lines ep esen
sigmoidal i s o he cu es. The in lec ion poin o he i cu e co esponds o he
pKa o he dye in he b ush. The a e age pKa was 1 and 3.8 in cha ged and neu al
b ushes, espec i ely.
Bulk Expe imen s o CF-solu ions
Va ia ion o NaCl concen a ion
The luo escence o 0.03 mM CF-solu ion is no a ec ed by he sal concen a ion.
Dependence o luo escence on pH
The pKa o ca boxy luo escein in bulk solu ion was de e mined by luo escence spec-
oscopy o a solu ion o 0.03 mmol/Ldye in dilu ed HCl and NaOH solu ions wi h an
ionic s eng h 0.01 M NaCl (see Figu e 4.8).
Sel quenching o CF
Sel quenching o CF, see Figu e 4.9.
Quenching o he dye by METAC
Quenching o CF by he monome o he polyme b ush (METAC), see Figu e 4.10.
CHAPTER 4. MECHANORESPONSIVE POLYELECTROLYTE BRUSHES 137
Figu e 4.8: Change o pH, CF concen a ion: 0.03 mM, sal concen a ion: 0.01 M
NaCl; Dec ease o luo escence by dec ease o pH, pKa o bulk solu ion: 5.2. (Li .:
pKa o bulk solu ion: a: 6.5)
De ails on o ce expe imen s
Fo ce-dis ance cu es
Exempla y o ce dis ance cu e o a so colloidal p obe in e ac ing wi h he b ush, see
Figu e 4.11.
Adhesion in wa e and NaCl solu ions
In e ac ion enge gy be ween p obe and b ush, depending on he solu ion condi ions,
see Figu e 4.12.
Hys e esis
Adhesion hys e esis be ween p obe and b ush, see Figu e 4.13
Co ela ion o in ensi y and p essu e p o ile
De ails on JKR heo y [17]
The sys em PDMS bead p essed agains a subs a e unc ionalized wi h a P(METAC-
co-AEMA) b ush can be desc ibed by con ac -mechanic heo y. H. He z p esen ed he
i s analy ic desc ip ion o wo iso opic, homogeneous linea elas ic bodies in con ac ,
bu wi hou adhesion. I one akes adhesion in o accoun he e a e se e al models which
apply o ce ain condi ions o con ac beha io . The wo mos common heo ies we e
de eloped by Johnson, Kendall and Robe s (JKR heo y) and De jaguin, Mulle and
CHAPTER 8. FURTHER PERSPECTIVES 240
The sensi i i y o he esponse and he o ce ange can possibly be ex ended by com-
bining o he mechanopho es wi h al e na i e b ush composi ions and a chi ec u es
[23]. Fo ins ance annealed polyelec oly e b ushes allow ex e nall igge ing o he
mechanochemical esponse by pH o ionic s eng h, o ice e sa. Tha means ha
e ical comp ession o he b ush could lead o a shi o he dissocia ion equilib ium.
This a ia ion could be measu ed using pH-sensi i e indica o s o example.
An al e na i e could be o use polyelec oly e gel ilms a he han polyme b ushes.
Polyme gels sys ems could allow al e na i e ou es o su ace unc ionaliza ion and
he usage o o he mechanopho es. They a e lexible in handling and s e ic hind ance
o he mechanopho e could be o e come. Also, measu emen s in ai could be possible.
Fo he unde s anding o he p ocesses in s ongly comp essed PMETAC b ushes, we
combined AFM o ce spec oscopy wi h polyme b ush heo y. Fi s expe imen s a e
unde way o s udy he e ec o b ush pa ame e s on he comp essibili y. These expe -
imen s a e e alua ed on basis o AdG heo y (de eloped by Alexande and de Gennes
[29, 30]). Also, he ela ion be ween esponse and comp essibili y, i.e. he s a e o
quenching as a unc ion o applied o ce is in es iga ed.
Fu he o he ypes o esponse will be add essed. A mo e speci ic esponse han
quenching is possible by using dyes, which show a shi in he emission spec um
( a he han a shi in in ensi y) in esponse o changes in he chemical en i onmen .
Fo ins ance seminaph ha hoda luo (SNARF), which esponds o changes o he dis-
socia ion equilib ium. Fo his pu pose, we ha e es ablished a syn hesis p o ocol o
he a achmen o SNARF dye o PMETAC polyme b ushes. In o de o quan i y he
esponse o SNARF dye, he de ec ion scheme was changed om luo escence in ensi y
mapping o mapping o spec oscopic p ope ies.
8.3.1 Unde s anding o he Mechano esponse
Fo he design o mechano esponsi e sys ems based on polyme b ushes we ha e o
unde s and how he b ush is a ec ed by he en i onmen and he applied o ce, and
how he esponse is ela ed o he comp ession s a e o he b ush.
B ush Comp esssion
We pe o med ( i s ) o ce spec oscopic expe imen s o gain in o ma ion abou he
comp essibili y o ca ionic PMETAC polyme b ushes wi h a co alen ly a ached 5(6)ca -
boxy luo escein (CF) [1] dependen on he ionic s eng h. We used he colloidal p obe

CHAPTER 8. FURTHER PERSPECTIVES 241
(CP) echnique, whe e a CP was a ached o an AFM can ile e using mic omanipu-
la ion. In a u he s ep he CP was unc ionalized wi h a 3-Aminop opyl di isop opyl
e hoxysilane (97%) o a oid elec os a ic a ac ion be ween he CP and he ca ionic
b ush. A e silaniza ion o ce dis ance da a we e eco ded in a d ople o aqueous
NaCl solu ion.
As expec ed, we could obse e ha he epulsi e o ces inc ease (s eng h and ange)
as he ionic s eng h Iis dec eased. This can be a ibu ed o mul iple o igins. On he
one hand he elec os a ic in e ac ions a e sc eened. In addi ion he b ush swells and
s e ic in e ac ions a e mo e dominan .
In a i s app oxima ion, we analyzed he measu emen s in e ms o he AdG heo y o
an asymme ic si ua ion (b ush/ no b ush; elec o s a ic in e ac ions a e neglec ed).
F(D)
2πR =2kBTH
35σ3/2"7D
H−5/4
+D
H7/4
−12# o D < H, (8.1)
As i can be seen in Figu e 8.7 he AdG model i s well o he eco ded da a (Fo he
Figu e 8.7: Fo ce measu emen s a PMETAC b ushes: Fo ce p o iles o NaCl sal
concen a ions o 0.1 M and 0.01 M Measu ed da a a e i ed wi h he AdG model.
i ing p ocedu e we included a displacemen pa ame e δbecause we could no each
he cons an compliance egime: D=D0−δ). The esul ing b ush pa ame e s a e
physically in he igh o de . The b ush heigh was 150 ±30 nm, and he sepa a ion
dis ance o g a ing poin s σ1/2= 15 ±3 nm o a sal concen a ion o 0.1 M. Fo a
concen a ion o 0.01 M he b ush heigh was 300 ±50 nm, and a sepa a ion dis ance
o g a ing poin s σ1/2= 19 ±4 nm. The ob ained alues o he b ush heigh a e
sligh ly o la ge compa ed o alues de ec ed using ellipsome y [1]. Howe e his can
CHAPTER 8. FURTHER PERSPECTIVES 242
a ibu ed o he elec os a ic epulsion o he sample and he p obe.
To analyze he e ec o swelling, we no malized he o ce p o iles as sugges ed by S.
Block [31]. The AdG model p edic s ha he s e ic in e ac ions scale linea wi h he
b ush heigh . The b ush heigh again scales wi h he sal concen a ion as H∝I−1/3.
Ob iously, he o ce p o iles should show he same beha io i hey a e plo ed o e
DI1/3, whe e Dis he sepa a ion dis ance o he p obe and he b ush. No maliza ion
o he esul ing o ce p o iles by I1/3should lead o a collapse o he cu es o di e en
sal concen a ions on o a mas e cu e. Following his p ocedu e he e ec o swelling
and he esul ing s e ic in e ac ions could be con i med as poin ed ou in Figu e 8.8
(The same p ocedu e can be applied o mean ield (MF) heo ies (and o he s). Fo
he MF app oach he o ce p o iles mus be no malized by I2/3. Howe e , escaling is
jus sucess ul i he o ce p o iles a e shi ed).
Figu e 8.8: No maliza ion o he o ce p o iles using he AdG model: Fo ce p o iles
collapse on o a mas e cu e i hey a e no malized as p edic ed by he AdG model.
Inse shows escaling using a mean ield model. Rescaling in ha case is jus sucess ull
i he o ce p o iles a e shi ed
In e p e a ion o he Response Func ion
In ou p e ious s udy on mechano esponsi e polyme b ushes we analyzed he mechano e-
sponse in he con ac zone o a so colloidal p obe ha is p essed agains he PMETAC
polyme b ush laye . In ou case, we could obse e luo escence quenching as esponse
o p essu e. F om hese measu emen s we could de e mine a esponse unc ion I(p),
which co ela es local luo escence in ensi y (I) o local p essu e (p). The p essu e
is calcula ed wi h use o he JKR heo y. To ela e he mechano esponse, i.e. s a e
CHAPTER 8. FURTHER PERSPECTIVES 243
o quenching o he applied o ce and he comp essibili y o he polyme b ush, we
can assume ha he applied p essu e pin he con ac zone o he colloidal p obe is
p opo ional o he osmo ic p essu e inside he polyme b ush
p(D) = posm =kBT
σ3/2"D
L−9/4
−D
L3/4#.(8.2)
In e molecula deac i a ion p ocesses, such as quenching, can be desc ibed using he
S e n-Volme equa ion [32].
I0
IQ
= 1 + KcQ,(8.3)
whe e I0is he in ensi y o luo escence wi hou quenching, IQis he in ensi y wi h
he quenche o he concen a ion cQand Kis he quenche a e. We could show in
ou p e ious s udy [1] ha he luo escence in ensi y o 5(6)ca boxy luo escein (CF)
is mainly quenched by METAC molecules (KcMETAC >> 1). Thus he in ensi y o
luo escein wi h METAC can be exp essed by
IMe ac =I0
1 + KcMe ac ≈I0
KcMe ac
=I0σ
KNMe ac
D⇒I∝D. (8.4)
This assump ion allows o in e p e he de ec ed ”in e se” esponse unc ion p(I)di-
ec ly as o ce-dis ance p o iles. Fo a con i ma ion o his hypo hesis we i ed he
eco ded esponse unc ions wi h Eq.8.2 whe e Dis eplaced by I. The shown cu es
Figu e 8.9: In e p e a ion o he Response Func ion: Response unc ions o H2O,
0.1 M NaCl and 1 M NaCl solu ion: da apoin s ( ep oduced om Re . [1]) i ed wi h
AdG p o iles (solid lines).
CHAPTER 8. FURTHER PERSPECTIVES 244
(Figu e 8.9) demons a e ha he measu ed da a poin s a e loca ed on he alling
edge o he AdG p o iles. Howe e , acco ding o he i he g a ing densi y dec eases
wi h dec easing sal concen a ion. Fu he expe imn s a e necessa y o a i y hese
p esump ions.
Conclusion and Ou look
In summa y, we in es iga ed he s e ic in e ac ions o mechano esponsi e polyme
b ush sys ems. We could show ha he AdG model can desc ibe he s e ic in e -
ac ions in he b ush laye s. Fu he expe imen s a e necessa y o con i m he obse ed
beha io . In u u e, we will pe o m o ce spec oscopic measu emen s on pa e ned
subs a e (a eas wi h and a eas wi hou b ush) o achie e an in e nal e e ence o he
b ush heigh . Also, his will help o sepa a e long and sho ange in e ac ions. The
e ec o b ush pa ame e s on o ce p o iles should be s udied as well. Fo his pu pose
he b ush heigh can be a ied by a change o he polyme iza ion ime. The g a -
ing densi y can be a ied using di e en silanes as ini ia o s o blocking he ini ia o
(g a ing si es) using sui able blocking molecules (Also o he a ia ions o he syn he-
sis p o ocol a e possible, e.g. ype ligand, sol en ). This will help o unde s and he
in luence o he b ush pa ame e s on comp essibili y and he mechano esponse. Fu -
he o ce expe imen s and escaling e alua ion can help o p o e expe imen ally, he
alidi y and limi a ion o he exis ing heo ies on polyme b ushes.
8.3.2 Change o he De ec ion Scheme
A mo e speci ic de ec ion scheme han luo escence quenching will help o unde s and
how mechanical ene gy con e s in o changes o he chemical en i onmen inside he
b ush. He e we in oduce an al e na i e o luo escence quenching using a pH sensi i e
luo opho e, i.e. seminaph ha hoda luo (SNARF). The physical p ope ies o his ype
o dye a e igge ed by he dissocia ion equilib ium inside he b ush. Va ia ion o his
equilib ium esul s in changes o he emission spec a.
Dye A achmen
The a ge was o bind SNARF molecules o he p ima y amine o he polyme
PMETAC b ushes, like shown in Figu e 8.10. Fo his pu pose, we used NHS-SNARF
so ha he succinimidyl es e eac s wi h he p ima y amine o ming a pep ide bond.
A e syn hesis o he copolyme PMETAC b ush (on glass slides) as es ablished in Re .
[1], a unc ionalized glass slide was sonica ed o 10 min in 1 M aqueous NaCl solu ion,
CHAPTER 8. FURTHER PERSPECTIVES 245
washed wi h wa e and d ied in a N2s eam. The NHS-SNARF (In i ogen # S22801)
was ea ed wi h 10 µldime hylsul oxid (DMSO) and incuba ed a oom empe a u e
o ca. 5 min. The dye solu ion was mixed wi h wa e o ge a inal dye concen a ion
o 0.281 mM, and was illed on he bo om o a cen i uge cap. A glass slide (wi h
he copolyme PMETAC polyme b ush) was placed in he cap, wi h he polyme ilm
owa ds he dye solu ion. A e eac ion ime o e nigh a oom empe a u e he glass
slide was insed wi h wa e and sonica ed 2 imes, each ca. 5 min, in 1 M aqueous NaCl
solu ion. Finally, he slide was washed wi h wa e and d ied in a N2-s eam.
Figu e 8.10: A achemen o SNARF o polyme b ushes
Cha ac e iza ion
Fo he cha ac e iza ion o he dye a achmen and o he esponse o he polyme
b ushes wi h co alen a ached SNARF dye we pe o med luo escence mic oscopy and
luo escence spec oscopy. The unc ionalized glass slides we e placed on a luo escence
mic oscope and images we e ake in a ange o pH 4 o pH 9 (pH solu ions wi h di e en
bu e s lis ed in Tab. 8.1). A colo change is clea ly isible (Figu e 8.11). This can be
ela ed o a shi in he emission spec a o he subs a es. To quan i y his al e a ion
we analyzed he a io o he in ensi y om he ed channel I ( ed luo escen emis-
sion) o he luo escen mic oscope and Iy he in ensi y o he yellow channel, ollowing
Re . [33, 34] (Figu e 8.12). F om hese calib a ion cu es we could de e mine pKa
o he co alen ly a ached SNARF [33, 34]. The mean alue o h ee slides could be
de e mined o pKa = 9 ±1.
Fu he mo e, we pe o med luo escence spec oscopy. Fo his pu pose he unc ion-
alized glass slides we e analyzed using a con ocal mic oscope in spec oscopy mode.
He e, o each wa eleng h in e al (3 nm) an in ensi y image was de ec ed o c ea e

CHAPTER 8. FURTHER PERSPECTIVES 246
Table 8.1: Bu e s ha we e used o s udy he esponse o PMETAC-SNARF b ushes
on pH.
pH composi ion
4 ci ic acid / NaCl / NaOH
5 ci ic acid / NaOH
6 ci ic acid / NaOH
7 KH2PO4/ Na2HPO4
8 Na2B4O7/ HCl
9 Na2B4O7/ KCl
10 Na2B4O7/ NaOH
11 Na2B4O7/ NaOH / KCl
12 Na2HPO4/ NaOH
A B C
D E F
G H I
Figu e 8.11: Fluo escence Mic oscope Images o SNARF unc ionalized b ushes: pH4
(8.11A) - pH12 (8.11I)
CHAPTER 8. FURTHER PERSPECTIVES 247
Figu e 8.12: Calib a ion cu e o he SNARF unc ionalized b ushes
spec al p o iles o he dye. Fo wo pH alues a clea change o he emission spec a
could be iden i ied (Figu e 8.13).
Figu e 8.13: Emission spec a o SNARF unc ionalized b ushes a pH7 and pH10
Conclusion and Ou look
In summa y, we ha e es ablished a p o ocol o a ach he pH-sensi i e dye seminaph-
ha hoda luo co alen ly o PMETAC polyme b ushes. The ob ained subs a es we e
cha ac e ized wi h espec o unc ionaliza ion and he esul ing luo escence p ope ies
as a unc ion o pH. Fu he s udies will e i y hese esul s. Follow up p ojec s a e
planned o s udy he chemical en i onmen inside polyelec oly e b ushes, wi h and
CHAPTER 8. FURTHER PERSPECTIVES 248
wi hou comp ession, by analysis o luo escence p ope ies o he b ush depending on
he con o ma ion o he polyme b ush. A quan i a i e e alua ion on he e ec o
hese chemical modi ica ions on esponse, in pa icula p essu e sensi i i y could be
ca ied ou in hese expe imen s. In ha con ex , annealed PE polyme b ushes and
polyelec oly e gels could be es ed as well.
Beside he ques ion abou comp essibili y and po en ial esponses such an app oach
can help o ”look” inside a b ush and, he eby, allows p o ing he exis ing heo ies on
polyme b ushes.
8.4 Re e ences
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Chemie-In e na ional Edi ion 50.41 (2011), pp. 9629–9632.
[2] M. K. Chaudhu y and G. M. Whi esides. “How o Make Wa e Run Uphill”. In:
Science 256.5063 (1992), pp. 1539–1541.
[3] M. K. Chaudhu y and P. S. Goohpa ade . “Noise-ac i a ed dissocia ion o so
elas ic con ac s”. In: Eu opean Physical Jou nal E 35.12 (2012).
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[6] E. A z , S. Go b, and R. Spolenak. “F om mic o o nano con ac s in biological
a achmen de ices”. In: P oceedings o he Na ional Academy o Sciences o he
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ome y mimicking bioa achmen de ices”. In: Ad anced Ma e ials 19.15 (2007),
pp. 1973–+.
[8] A. del Campo, C. G eine , and E. A z . “Con ac shape con ols adhesion o
bioinspi ed ib illa su aces”. In: Langmui 23.20 (2007), pp. 10235–10243.
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[9] L. F. Boesel e al. “Gecko-Inspi ed Su aces: A Pa h o S ong and Re e sible
D y Adhesi es”. In: Ad anced Ma e ials 22.19 (2010), pp. 2125–2137.
[10] D.-M. D o le e al. “Insigh s in o he Adhesi e Mechanisms o T ee F ogs using
A i i cial Mimics”. In: Ad anced Func ional Ma e ials (2012).
[11] C. G eine , A. del Campo, and E. A z . “Adhesion o bioinspi ed mic opa e ned
su aces: E ec s o pilla adius, aspec a io, and p eload”. In: Langmui 23.7
(2007), pp. 3495–3502.
[12] J. Cui, V. San Miguel, and A. del Campo. “Ligh -T igge ed Mul i unc ionali y
a Su aces Media ed by Pho olabile P o ec ing G oups”. In: Mac omolecula
Rapid Communica ions 34.4 (2012), pp. 310–329.
[13] C. Y. Hui e al. “Design o biomime ic ib illa in e aces: 2. Mechanics o en-
hanced adhesion”. In: Jou nal o he Royal Socie y In e ace 1.1 (2004), pp. 35–
48.
[14] Y. Menguec e al. “Gecko-Inspi ed Con ollable Adhesi e S uc u es Applied o
Mic omanipula ion”. In: Ad anced Func ional Ma e ials 22.6 (2012), pp. 1246–
1254.
[15] M. P. Mu phy, B. Aksak, and M. Si i. “Gecko-inspi ed Di ec ional and Con-
ollable Adhesion”. In: Small 5.2 (2009), pp. 170–175.
[16] D. Pa e ka e al. “Bioinspi ed p essu e ac ua ed adhesi e sys em”. In: Ma e ials
Science andja Enginee ing C-Ma e ials o Biological Applica ions 31.6 (2011),
pp. 1152–1159.
[17] J. Yu e al. “Gecko-Inspi ed D y Adhesi e o Robo ic Applica ions”. In: Ad-
anced Func ional Ma e ials 21.16 (2011), pp. 3010–3018.
[18] G. Ca bone and E. Pie o. “S icky Bio-inspi ed Mic opilla s: Finding he Bes
Shape”. In: Small 8.9 (2012), pp. 1449–1454.
[19] G. Ca bone, E. Pie o, and S. N. Go b. “O igin o he supe io adhesi e pe -
o mance o mush oom-shaped mic os uc u ed su aces”. In: So Ma e 7.12
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[20] M. Scha go , V. L. Popo , and S. Go b. “Sp ing model o biological a achmen
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CHAPTER 9. SUMMARY 256
su aces has been in es iga ed. The obse a ions a e co ela ed o o ce-spec oscopic
measu emen s. Fo his pu pose mic on sized model pa icles we e p epa ed which
could be used as p obes in a colloidal p obe AFM se up. These p obes we e used
o measu e he in e ac ions be ween hese ”mic o SPBs” and posi i ely o nega i ely
cha ged su aces. We showed ha he adhesi e p ope ies o he SPBs can be con-
olled by he ionic s eng h o he su ounding solu ion and he subs a e cha ge. A
low ionic s eng h, he nega i ely cha ged SPBs p e e ably adso b on o he posi i ely
cha ged subs a es. Abo e a c i ical ionic s eng h, his selec i i y is los . Due o
seconda y in e ac ions he pa icles adso b in hese condi ion on bo h sys ems equally.
The obse a ions ha e been used o build up hie a chical s uc u es om SPBs, which
a e adso bed om a suspension. The hie a chy can be con olled by he mic o-con ac
p in ing echnique. Such sys ems can be exempla ily used o op ical applica ions, i a
me al co e is employed.
Fu he mo e, highly ac i e su aces ha e been p epa ed on basis o polyelec oly e-
copolyme micelles. Fo his, a iblock e polyme is used (BMAADq: polybu adi-
ene (B), poly(me hac ylic acid) (MAA), and qua e nized poly(2-(dime hylamino)e hyl
me hac yla e) (Dq)) which o ms micelles in solu ion composed o a hyd ophobic co e,
a middle block o an annealed polyme b ush, and a posi i ely cha ged co ona. These
micelles ha e been disposed in mul ilaye s using he laye -by-laye me hod wi h a neg-
a i e polyme . The ad an age o he micelles used in his app oach is ha he cen al
block is shielded by he o he wo blocks om complexa ion wi h he mul ilaye . Be-
cause o he cen al block, he micelles and hus he mul ilaye s a e s ongly dependen
on he pH o he en i onmen . A a low pH, he middle block con ac s, whe eas i
is highly swollen a high pH. In his hesis we in es iga e he swelling beha io o he
mul ilaye -sys em on he numbe o deposi ion s eps and as a unc ion o he pH alue.
Fu he , we co ela e he swelling beha io wi h po osi y and mechanical p ope ies o
he mul ilaye s. Due o hei high sensi i i y, hese esponsi e laye s a e sui able o
he design o ac ua o s.
In summa y, his wo k b idges om undamen al polyme chemis y (chemis y o
polyme b ushes) o e physics (con ac mechanics, adhesion, and polyme physics) o
po en ial applica ions (senso s and ac ua o s). Scien i ic inpu has been p o ided o
he esea ch on polyme b ushes, mechano esponsi e sys ems, o ce sensing, and ac i e
ma e ials, as well as con ac mechanics, colloidal a angemen , and (bio) adhesion.

10
Zusammen assung
257
CHAPTER 10. ZUSAMMENFASSUNG 259
In diese A bei we den sogenann e ”geladene Polyme Bü s en” un e such . Dabei lieg
de Fokus au de Un e suchung und dem Ve s ändnis de schal ba en Eigenscha en
diese Polyme Obe lächen. Dazu we den sowohl neue Me hoden aus Kombina ion
on K a Spek oskopie und op ische Mik oskopie einge üh , sowie be ei s e ablie e
physikalisch-chemische Techniken e wende .
Polyme Bü s en bilden sich aus, wenn iele Polyme ke en in einem Mindes abs and
an eine Subs a Obe läche angebunden we den, so dass de en Wechselwi kungspo en-
iale übe lappen. Dadu ch ich en sich die Polyme e aus und bilden einen esponsi en
Film. Das Anbinden de Polyme ke en e olg in diese A bei mi de sogenann en
”G a ing om” Me hode, bei de eine Polyme isa ion di ek on de Obe läche aus-
ge üh wi d.
Die Syn hese de Polyme Bü s en is seh lexibel im Hinblick au ih e molekula e
A chi ek u , da jede A on Polyme isa ion anwendba is , solange de benö ig e
Ini ia o an die Obe läche gebunden we den kann. Des Wei e en häng die Kon o -
ma ion und dami die physikalischen Eigenscha en de Polyme Bü s en, s a k on
de en Umgebung ab, insbesonde e bei geladenen Polyme Bü s en. Auße dem is es
möglich unk ionelle G uppen an die Polyme e anzubinden, so dass diese du ch ex e ne
S imuli geschal e we den können. Dami e weisen sich geladene Polyme Bü s en
als exzellen e Baus eine ü schal ba e Obe lächen. Schal en lassen sich Obe läch-
eneigenscha en, wie zum Beispiel Adhäsion, Ladung, Reibung, Mechanik, op ische
Eigenscha en, Po osi ä ode Biokompa ibili ä . Dieses Schal en kann du ch Ve än-
de ung de Umgebung wie Ionens ä ke, pH-We ode Tempe a u und du ch ex e ne
S imuli wie elek ische ode magne ische Felde , D uck ode Lich ausgelös we den.
Dami eignen sich solche Sys eme ideal, um Senso en au Umgebungseigenscha en ode
ex e ne S imuli bzw. Ak ua o en au zubauen.
Diese lassen sich zum Beispiel in de S ammzellen o schung einse zen um Zellen zu
s imulie en und de en Wachs um und Eigenscha en zu kon ollie en.
Fü solche Anwendungen is ein undamen ales Ve s ändnis de Polyme Bü s en, de en
Schal eigenscha en und den dami e bundenen Obe lächeneigenscha en no wendig.
Im e s en Teil diese A bei we den neue Messme hoden ü die Un e suchung on
schal ba en Sys emen o ges ell . Deswei e en we den geladene Polyme Bü s en ü
den Au bau on Senso en und ü die geziel e Eins ellung on Obe lächeneigenscha en
e wende .
CHAPTER 10. ZUSAMMENFASSUNG 260
Es is die kolloidale K a -Spek oskopie mi weichen Pa ikeln (engl. So colloidal
p obe: SCP) en wickel wo den. Diese Me hode kombinie die Vo eile eines JKR-
Messge ä s (g oße Kon ak läche) und de AFM K a spek oskopie (hohe K a au lö-
sung). Du ch ein am o de en Ende eine AFM-Bla ede (Can ile e ) angeb ach es
weiches Pa ikel aus Polydime hylsiloxan (PDMS) wi d ein de inie e mik oskopische
Kon ak e zeug . Dazu wi d das Pa ikel mi kon ollie e K a gegen eine Obe läche
ge ah en, wodu ch sich eine Kon ak läche ausbilde . Diese kann mi els Mik oin e -
e ome ie beobach e we den. Mi Hil e on Kon ak -Mechanik Modellen lassen sich
so aus den gemessenen G ößen e schiedene Pa ame e wie e wa die Adhäsionsene gie
p o Einhei s läche und Spannungs e eilung in de Kon ak zone bes immen.
Diese Me hode is an e schiedenen Modellsys emen mi bekann e Obe lächenchemie
zu Bes immung de Adhäsionsene gie p o Einhei s läche ge es e wo den. Dabei kann
kla zwischen kapilla en, hyd ophilen und hyd ophoben Wechselwi kungen un e schieden
we den. Des Wei e en e möglich die SCP Me hode du ch ih e hohe Sensi i i ä die Un-
e suchung eines b ei en Spek ums an Sys emen und die Au klä ung wissenscha liche
F agen.
Kenn nisse übe die Spannungs e eilung inne halb eines Kon ak s sind undamen al
ü das Ve s ändnis on Kon ak phänomenen, insbesonde e au de kolloidalen Skala.
Au de Basis on mechano esponsi en Bü s ensys emen is ein Senso en en wickel
wo den, de seine op ischen Eigenscha en als Funk ion de angeleg en K a ände .
Dies e möglich Spannungs e eilungen mi hohe la e ale Au lösung (<1µm) und
hohe D uckemp indlichkei (<10 kPa) zu de ek ie en.
Diese Senso bes eh aus ka ionischen, luo eszenzma kie en Polyelek oly Bü s en
(Poly [2 - (Me hac yloyloxy) e hyl] ime hyl-ammoniumchlo id (PMETAC) Bü s en,
ma kie mi einem ko alen angebundenen Fluo eszenz a bs o , 5 (6) Ca boxy luo-
escein (CF)). Die Polyme Bü s en ände n ih e Fluo eszenzeigenscha en abhängig
on ih em Komp essionszus and. Dieses Sys em is mi de SCP Me hode un e such
und kalib ie wo den. Dazu wi das weiche Pa ikel mi de Polyme Bü s e in Kon-
ak geb ach . Un e Komp ession bilde sich eine Kon ak läche aus. Die op ischen
Signale aus de Kon ak läche, Fluo eszenzände ungen, können mi einem Kon okalen
Mik oskop mi hohe Au lösung de ek ie we den. Dabei kann in de Kon ak läche
eine lokal om O abhängige Fluo eszenzin ensi ä s-Ve eilung beobach e we den.
Um den Ve lau diese Ve eilung zu e s ehen, is die Kon ak zone mi einem Kon ak -
mechanik Modell, en wickel on Johnson, Kendall und Robe s, besch ieben wo den.
Dabei zeig sich, dass un e Komp ession die Fluo eszenzin ensi ä kleine wi d. An-
CHAPTER 10. ZUSAMMENFASSUNG 261
de e sei s nimm die Fluo eszenzin ensi ä zu, wenn man an den Bü s en zieh . Mi
diesen Übe legungen is es möglich eine An wo unk ion zu bes immen, die de lokalen
Fluo eszenzin ensi ä einen lokalen D uck zuo dne . Physikalisch/Chemisch kann die
Fluo eszenzände ungen einem ”Quenching Mechanismus” zugeo dne we den. Auße -
dem is das Signal e e sibel und s abil. All diese Eigenscha en machen ein solches
mechano esponsi es Sys em zu eine einziga igen Basis ü den Au bau on D uck
Senso en.
Da übe hinaus we den d ei Pe spek i en de mechano esponsi en Polyme Bü s en
disku ie : 1) Analy ische Besch eibung des Zusammenhangs on Komp ession und Än-
de ung des Fluo eszenzsignals; 2) Al e na i e De ek ionsmechanismen wie Ände ung
des Emissionsspek ums als Funk ion de Bü s enkomp ession du ch Modi ika ion des
Mechanopho s und 3) Anwendungsmöglichkei en au die Un e suchung on biomime is-
chen Sys emen, wie zu Au klä ung de beme kenswe en Ha eigenscha en on Geck-
o üßen.
Lich kann nich nu als An wo unk ion e wende we den, sonde n auch als T igge .
Es is ein Sys em on Polyme Bü s en e ablie wo den, das au g und de Eins ahlung
on Lich seine chemische S uk u ände . Diese Polyme Bü s en (PNVOCMA)
bes ehen aus einem Me hac yla Rückg a mi ionisie ba em -COOH Sei eng uppen,
die du ch Bes ahlung des pho osensi i en 6-ni o e a yloxy Ca bonyl (NVOC) ei
we den und eine Poly (Me hac ylsäu e) (PMAA) Bü s e ausbilden. Dadu ch ände
sich die Obe läche on neu al zu nega i geladen und wi d hyd ophil. Mi diesen
pho o esponsi en Sys emen is es möglich Obe lächeneigenscha en nich nu zwis-
chen ih en Ex emwe en hin und he zu schal en, sonde n diese du ch Anpassung de
Belich ungszei und In ensi ä de inie einzus ellen und dami ü die gewünsch e An-
wendung zu op imie en.
In diese A bei wi d gezeig , wie sich die Belich ungszei au den Umwandlungszu-
s and de Polyme Bü s e auswi k und wiede um was ü einen Ein luss das au
Bene zba kei , Adhäsion und Reibung ha . Mi Zunahme de Belich ungszei wi d die
Wasse au nahme de Bü s e g öße . Auße dem e ände n sich mi de Pho okon e sion
auch die Obe lächenk ä e. Mi Zunahme de Bes ahlungsdaue we den Reichwei e
und S ä ke on epulsi en Wechselwi kungen zwischen de Polyme Bü s e und eine
Can ile e spi ze aus Siliziumdioxid g öße und die Ha eigenscha en nehmen ab. An-
de e sei s wi d die Reibung zwischen de Sonde und dem Subs a mi Zunahme de
Belich ungszei g öße , was du ch Subs a e ek e e klä we den kann. Diese pho o e-
sponsi en Sys eme können zum Beispiel dazu e wende we den, um Wasse kondensa-

CHAPTER 10. ZUSAMMENFASSUNG 262
ion und die Bewegung on Flüssigkei en zu manipulie en. Dies kann in ”Wasse e n e-”
ode Mik o luidik-Sys emen eingese z we den. Eine wei e e Anwendung is das geziel e
Ankoppeln ode Ab ennen on chemischen Ve bindungen ode biologischen Objek en.
Dies kann beispielsweise in ”Lab-on-Chip”-Ge ä en e wende we den.
Al e na i zu den gezeig en Ansä zen on Polyme Bü s en au lachen Subs a en
lassen sich esponsi e Sys eme auch aus kolloidalen Baus einen au bauen. De zwei e
Teil diese A bei be ass sich mi dem Au bau on Schal ba en Sys emen aus solchen
Baus einen. Dies b ing einige Vo eile mi sich: Die Handhabung on kolloidalen
Baus einen is in de Regel ein ach, bzw. läss sich die Ano dnung diese du ch geziel e
Selbs o ganisa ion gu kon ollie en. Auße dem können die kolloidalen Baus eine di-
e se Funk ionali ä en besi zen und du ch den kolloidalen Cha ak e ganz neue Eigen-
scha en gene ie en, beispielsweise die Lokalisie ung on Lich ode kollek i e op ische
P ozesse.
Vo ausse zung ü solche Anwendungen is das Ve s ändnis de Wechselwi kungseigen-
scha en mi dem Subs a und des Ve hal ens solche Baus eine abhängig on ih e
Umgebung.
In diese A bei is das Adso p ions e hal en on geladenen sphä ische Polyme Bü s en
(SPBs) bes ehend aus einem Polys y ene (PS) Ke n und angebundenen Polys y ene
Sul ona e (PSS) Ke en) au geladenen Obe lächen un e such und dieses mi k a -
spek oskopischen Messungen ko elie wo den. Dazu sind Modell-Pa ikel he ges ell
wo den, die als kolloidale Sonden an einem AFM-Can ile e e wende we den können.
Mi diesen Sonden und Messung de Wechselwi kungen zwischen diesen ”Mik o-SPBs”
und posi i bzw. nega i geladenen Obe lächen wi d gezeig , dass die Ha eigen-
scha en de SPBs du ch Ionens ä ke und Ladung des Subs a s ges eue we den kön-
nen. Bei ge inge Ionens ä ke adso bie en die nega i geladenen SPBs o zugsweise au
den posi i geladenen Subs a en. Ab eine k i ischen Ionens ä ke geh diese Selek i -
i ä abe e lo en und die Pa ikel adso bie en au g und sekundä e Wechselwi kungen
au beiden Sys emen gleich gu . Dieses Ve s ändnis wi d wei e dazu genu z , um hi-
e a chische S uk u en aus SPBs au zubauen, die aus eine Suspension adso bie we -
den. Die S uk u ie ung kann hie bei du ch die Mik okon ak d uck-Technik ges eue
we den. Ve wende man me allische Ke ne (ans a de bei unse em Modellsys em
e wende en PS Ke ne) lassen sich ü op ische Anwendungen in e essan e S uk u en
au bauen.
CHAPTER 10. ZUSAMMENFASSUNG 263
Wei e hin sind ak i e Obe lächen du ch Polyelek oly Copolyme - Mizellen he ges ell
wo den. Dazu we den T iblock e polyme e e wende (BMAADq: Polybu adienblock
(B), einem pH-sensi i en Polyme hac ylsäu e-Mi elblock (MAA) und einem pe ma-
nen geladenen Block aus qua e nisie em Poly(2-dime hylamino)e hylme hac yla )
(Dq)), welche in Lösung Mizellen mi einem hyd ophobischen Ke n, einen Mi el-Block
aus eine schwachen Polyme Bü s e und eine posi i geladenen Ko ona ausbilden.
Diese Mizellen we den mi de ”Laye -by-Laye -Me hode” mi einem nega i geladenem
Pa ne -Polyme in Mul ilagen angeo dne . Du ch den Mi elblock sind die Mizellen,
und dami auch die Mul ilagen s a k on dem pH We de Umgebung abhängig. Bei
einem nied igen pH We zieh sich de Mi elblock zusammen, wogegen e bei einem
hohen pH We s a k gequollen is . De Vo eil de hie e wende en Mizellen is ,
dass de Mi elblock du ch die ande en beiden Blöcke on de Komplexie ung in de
Mul ilage abgeschi m is . In diese A bei haben wi das Quell e hal en diese Sys-
eme in den Mul ilagen un e such und dieses abhängig on Anzahl de Mul ilagen
und pH-We quan i izie . In einem wei e en Sch i haben wi dieses Ve hal en mi
Po osi ä und mechanischen Eigenscha en de Mul ilagen ko elie . Du ch ih e hohe
Sensi i i ä eignen sich diese esponsi en Lagen seh gu als Ak ua o -Ma e ialien.
Zusammen assend wu de in diese A bei eine B ücke on Polyme Chemie (Chemie de
Polyme bü s en) übe die Physik (Kon ak mechanik, Adhäsion und Polyme physik)
zu po en iellen Anwendung (Senso en und Ak ua o en) geschlagen. Dabei wu den
wissenscha liche Bei äge zu Fo schung an Polyme Bü s en, mechano esponsi en
und ak i en Ma e ialien, K a e kennung und Kon ak mechanik, kolloidale Ano d-
nung und (Bio-) Ha ung geleis e .
A
Theo y o Polyme B ushes
265

Danke!
Wie sag man nach so ielen Jah en am bes en allen Danke, die zum Gelingen eines
P ojek s, wie de o liegenden A bei beige agen haben? Um nich den ein ode an-
de en zu e gessen möch e ich mich e s einmal g undsä zlich bei ALLEN bedanken
mi denen ich zusammen a bei en du e. So nun de Reihe nach:
And eas Fe y, Danke ü die supe Be euung, die ielen in e essan en Diskussionen,
die F eihei mich en al en zu können und auch da ü , das ein ode ande e P ojek mi
ans oßen zu dü en. Es ha mi eh lich imme iel Spaß gemach mi Di zu a bei en.
Meis ens ha es sich dahe ga nich wie A bei ange ühl . Auße dem Danke, dass ich
so iele Kon e enzen besuchen und dadu ch die Wel besse kennenle nen du e.
Sybille Zimme mann, du weiß , ohne Dich wä e de Leh s uhl nich so wie e is .
Du häl s deine ”Familie” ech supe zusammen. Danke ü alles was du ü mich
e ledig has .
Johanna Bünsow, di möch e ich Danke sagen ü Deine Ein üh ung in die Wel de
Polyme -Bü s en, Deine Geduld, wenn ich mal e was nich gleich e s anden habe und
na ü lich das Ko ek u lesen diese A bei . Ich eue mich ein ach, dass wi au dem
Weg de Wissenscha F eunde gewo den sind, juhu!
An diese S elle möch e ich auch Wilhelm Huck danken, de iel zu meinem Polyme -
Bü s en Ve s ändnis beige agen ha und ü die gu e Koope a ion.
A ancha del Campo, Danke dass ich bei Euch am MPI ü Polyme -Fo schung in
Mainz imme willkommen wa , die ne e A mosphä e und die ielen in e essan en
Diskussionen. Auße dem na ü lich ü die gu e Zusammena bei an unse en P ojek en.
Hie auch Danke an Di k, Michael und Jiaxi ü die olle Zusammena bei .
273
DANKE 274
Danke an S ephan Block, ü olle Disussionen und den egen E-Mail Kon ak .
Ein besonde e Dank gil all meinen Kollegen aus de Physikalische Chemie II.
Ich hab hie bei euch imme eine supe A bei sa mosphä e und Hil sbe ei scha o ge-
unden und and es imme oll, mein Wissen so gu wie möglich mi Euch zu eilen.
Ich denke, die Kombina ion Chemie/ Physik wa nich schlech , und jede ha e e was
da on. Ich hab jeden alls iel on Euch gele n !
Besonde s möch e ich mich bei Daniel bedanken, ü die ielen Momen e, die wi zusam-
men ha en, Melani ü die ielen in e essan en Diskussionen und Hil es ellungen bei
e schiedens en F agen, Ben da ü , dass Du so bis , wie Du bis und ü das Ko ek-
u lesen on Abschni en diese A bei , Ch is da ü , dass Du imme posi i wa s und
o Ideen sp ühs , Ch is oph ü die olle Zusammena bei und die Un e nehmungen
die wi zusammen ha en, Be nha d ü die Ein üh ung in die Kle e ei, Ma in ü
Deine Gesellscha , Inna ü in e essan e Diskussionen und ü das Ko ek u lesen on
Abschni en diese A bei , Max, Mo iz und Jens ü die Zusammena bei und die
ollen Sp üche. Geo g Papas a ou danke ich ü die ielen in e essan en Diskussio-
nen. Auße dem möch e ich Alex und S ephan da ü danken, dass Ih mich in die PC
II einge üh hab , Julia und Ka ja ü die lus igen und in e essan en Gesp äche und
Öznu ü die F eundscha . Danke Euch allen ü Eu e Mo i a ion, die in e essan en
Diskussionen und den Spaß, den wi zusammen ha en.
A bei en geh bei mi abe nich ohne F eunde und Un e nehmungen auße halb de
Uni. Bei allen meinen F eunden aus de Physik, Spo und den Ande en (Ih
wiss schon, wen ich so meine...) möch e ich mich ü all die Jah e olle Spaß, Spo
und na ü lich gu e Zusammena bei bedanken und da ü , dass ich du ch Euch den
Blick ü die wesen lichen Dinge behal en habe.
So, je z kommen wi zu den wich igs en Menschen in meinem Leben.
E s einmal ein ieseng oße Dank, den man ga nich in Wo e assen kann, an meine
neu dazugewonnene Familie (Wagne , Schul e), da ü , dass ich mich bei Euch gebo -
gen ühle.
De g öß e Dank zum Schluss gil Euch, meine Familie daheim und Di , Susanne,
meine kleinen Fee. Danke Susanne ü die unglaublichen Jah e und Momen e, die wi
zusammen ha en, und dass Du mich so nimms , wie ich bin! Danke, Mama, Papa, T,
und Regina ü Eu e mo alische Un e s ü zung in allen Lebenslagen, du ch die ich de
we den konn e, de ich je z bin. Ich bin ganz zu ieden dami !
E klä ung
Die o liegende A bei wu de on mi selbs s ändig e ass und ich habe dabei keine
ande en als die angegebenen Hil smi el und Quellen benu z .
Fe ne habe ich nich e such , ande wei ig mi ode ohne E olg eine Disse a ion
einzu eichen ode mich de Dok o p ü ung zu un e ziehen.
Johann E a h
275