Template-Directed Synthesis of One-Dimensional Hybrid Nanostructures from Cylindrical Polymer Brushes

Templa e-Di ec ed Syn hesis o One- Dimensional Hyb id Nanos uc u es om Cylind ical Polyme B ushes DISSERTATION zu E langung des akademischen G ades eines Dok o s de Na u wissenscha en (D . e . na .) an de Bay eu he G aduie enschule ü Ma hema ik und Na u wissenscha en de Uni e si ä Bay eu h o geleg on Ma kus Müllne Gebo en in Ambe g Bay eu h, 2012 Die o liegende A bei wu de in de Zei on Feb ua 2009 bis Janua 2012 in Bay eu h am Leh s uhl Mak omolekula e Chemie II un e Be euung on He n P o . D . Axel H.E. Mülle ange e ig . Volls ändige Abd uck de on de Bay eu he G aduie enschule ü Ma hema ik und Na u wissenscha 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 am: 02.02.2012 Zulassung du ch die P omo ionskommission: 14.02.2012 Wissenscha liches Kolloquium: 07.05.2012 Am ie ende Dekan: P o . D . Bea e Lohne P ü ungsausschuss: P o . D . Axel H.E. Mülle (E s gu ach e ) P o . D . Jose B eu (Zwei gu ach e ) P o . D . Ca lo Un e zag (Vo si z) P o . D . And eas Fe y A day wi hou laugh e is a day was ed Cha lie Chaplin To My Family and I a Table o Con en s Table o Con en s Summa y ............................................................................................................................. 1 Zusammen assung.............................................................................................................. 3 Glossa y .............................................................................................................................. 7 Chap e 1 – In oduc ion ................................................................................................ 11 One-Dimensional Hyb id Nanos uc u es ................................................................... 11 1. Cylind ical Polyme B ushes ..................................................................................... 12 1.1 Cylind ical Polyme B ushes ia G a ing App oaches ................................................ 13 1.1.1 S uc u al Composi ions o Cylind ical Polyme B ushes............................................. 17 1.1.2 Co e-Shell and Co e-Shell-Co ona Block Copolyme B ushes ..................................... 18 1.1.3 S a is ical, G adien , Block and Janus-Type Cylind ical Polyme B ushes .................... 20 1.1.4 B anched, Mac ocyclic and Mul ig a Polyme B ushes ............................................. 23 1.2 Cylind ical Polyme B ushes om Block Copolyme s ................................................. 24 1.3 P ope ies o Cylind ical Polyme B ushes ................................................................. 26 1.3.1 Solu ion P ope ies.................................................................................................... 26 1.3.2 Cylind ical Polyme B ushes on Su aces and in he Bulk ............................................ 28 1.4 Applica ions o Cylind ical Polyme B ushes.............................................................. 30 2. One-Dimensional Hyb id O ganic-Ino ganic Nanos uc u es ....................................... 32 2.1 Templa e-Di ec ed App oaches Towa d One-Dimensional Hyb id Ma e ials ................ 33 2.1.1 Cylind ical Polyme B ushes as So Templa es o Fab ica ion o One-Dimensional Hyb id Nanoma e ials ............................................................................................... 34 2.1.2 Sel -Assembled One-Dimensional Templa es om Solu ion ........................................ 36 2.1.3 Sel -Assembled One-Dimensional Templa es om Bulk ............................................. 38 2.1.4 Biological and O he One-Dimensional Templa es ...................................................... 39 2.2 Po ous Memb ane-Based Templa es .......................................................................... 40 2.3 Elec ospinning......................................................................................................... 40 3. Aim o he Thesis ..................................................................................................... 41 Re e ences ............................................................................................................... 42 Chap e 2 – O e iew o he hesis ................................................................................. 49 2.1 O gano-Silica Hyb id Nano ubes ............................................................................... 50 2.2 Ana ase Nano ubes ................................................................................................... 53 2.3 Silica Nanowi es and Nano ubes ................................................................................ 56 2.4 Mesos uc u ing o TiO2 Nanoc ys als in o One-Dimensional Nanos uc u es ............... 59 2.5 Indi idual Con ibu ions o Join Publica ions ............................................................. 62 Re e ences .................................................................................................... 64 Chap e 3 Wa e -Soluble O gano-Silica Hyb id Nano ubes Templa ed by Cylind ical Polyme B ushes .................................................................................................................... 65 Chap e 4 Templa e-Di ec ed Mild Syn hesis o Ana ase Nano ubes wi hin Cylind ical Co e-Shell- Co ona Polyme B ushes ........................................................................................... 87 Zusammen assung 6 Glossa y 7 Glossa y 1D one-dimensional 1 H-NMR p o on nuclea magne ic esonance AAO anodized aluminium oxide AFM a omic o ce mic oscopy AMA allyl me hac yla e ATRP a om ans e adical polyme iza ion B ij 58 polyoxye hylene(20) ce yl e he CNT ca bon nano ubes CPB(s) cylind ical polyme b ush(es) CRP con olled adical polyme iza ion C yo-TEM c yogenic ansmission elec on mic oscopy CTAB hexadecyl ime hylammonium b omide CuAAC coppe -ca alyzed azide-alkyne cycloaddi ion D dis ance DCE dichlo oe hane DLS dynamic ligh sca e ing DMAEMA 2-(dime hylamino)e hyl me hac yla e DP n numbe -a e age deg ee o polyme iza ion EDX ene gy dispe si e X- ay spec oscopy FWHM ull wid h o hal maximum GMA glycidyl me hac yla e GPC gel pe mea ion ch oma og aphy GTP g oup ans e polyme iza ion H2SO4 sul u ic acid HCl hyd ogen chlo ide HF hyd ogen luo ide HR-TEM high esolu ion ansmission elec on mic oscopy IPEC in e polyelec oly e complex l m leng h pe monome uni l p pe sis ence leng h Luci in TPO® [diphenyl(2,4,6- ime hylbenzoyl)phosphine oxide] MWCNT mul i-walled CNTs MWD molecula weigh dis ibu ion nBA n-bu yl ac yla e NMP ni oxide media ed polyme iza ion NP(s) nanopa icle(s) OEGMA oligo(e hylene glycol) me hyl e he me hac yla e OsO4 osmium e oxide P2VP poly(2- inylpy idine) PAA poly(ac lyic acid) Glossa y 8 PAMA poly(allyl me hac yla e) PAPTS poly(3-ac yloylp opyl ime hoxysilane) PB polybu adiene PBIEM poly(2-b omoisobu y yloxye hyl me hac yla e) PCEMA poly(2-cinnamoyle hyl me hac yla e) PCEVE poly(chlo oe hyl inyl e he ) PCL poly(ε-cap olac one) PDADMAC poly(diallyldime hylammonium)chlo ide PDMAEMA poly(2-(dime hylamino)e hyl me hac yla e) PE polye hylene PEG polye hylene gylcol PFS poly( e ocenyldime hylsilane) PGMA poly(glycidyl me hac yla e) PHEMA poly(hyd oxye hyl me hac yla e) PI polyisop ene PLA poly(lac ic acid) PMDETA N,N,N',N",N''-pen ame hyldie hylene iamine PMETAI poly{[2-(me hac yloyloxy)e hyl] ime hylammonium iodide} PMMA poly(me hyl me hac yla e) PMS 4-(py olme hyl)s y ene PnBA poly(n-bu yl ac yla e) PNIPAM poly(N-isop opylac ylamide) POEGMA poly[oligo (e hylene glycol) me hyl e he me hac yla e] POSS polyhed al oligome ic silsesquioxane PS polys y ene PSS poly(s y enesul ona e), poly(s y enesul onic acid) P BA poly( e -bu yl ac yla e) PTEPM poly(3-( ie hoxysilyl)p opyl me hac yla e) PTMS-HEMA poly(2-( ime hylsiloxy)e hyl me hac yla e) PVP poly( inylpy olidone) PXRD powde X- ay di ac ome y QD quan um do RAFT e e sible addi ion agmen a ion ans e polyme iza ion RI e ac i e index ROMP ing-opening me a hesis polyme iza ion ROP ing-opening poylme iza ion SAED selec ed a ea elec on di ac ion SDS sodium dodecyl sulpha e SDV gel s y enedi inylbenzene gel SEC size exclusion ch oma og aphy SEM scanning elec on mic oscopy SiO 1.5 silsesquioxane SiO 2 silicon dioxide, silica Glossa y 9 SLS s a ic ligh sca e ing Sn(Oc )2 in(II) 2-e hylhexanoa e TALH i anium(IV) bis(ammonium lac a e) dihyd oxide BA e -bu yl ac yla e TEM ansmission elec on mic oscopy TGA he mog a ime ic analysis THF e ahyd o u an Ti(OBu)4 i anium(IV) bu oxide TiO2 i anium dioxide, i ania TMOS e ame hyl o hosilica e TMS-HEMA 2-( ime hylsilyloxy)e hyl me hac yla e TMV obacco mosaic i us Tween 60 polyoxye hylene so bi an monos ea a e Glossa y 10 Chap e 1 – In oduc ion 11 Chap e 1 – In oduc ion One-Dimensional Hyb id Nanos uc u es The demand o ad anced unc ional ma e ials wi h no el p ope ies has led o a con inually expanding esea ch a ea ha co e s no only chemis y, bu also biology, physics and ma e ials sciences. Nanos uc u ed ma e ials, which a e ma e ials wi h s uc u al ea u es o a leas one-dimension in he ange o 1-100 nm, ha e become one o he ho es opics in he ield o ma e ials science.1 The eason o he inc eased in e es in nanoma e ials lies in hei unique elec ical, op ical, magne ic, he mal, mechanical and chemical p ope ies when compa ed o hei bulk pa en coun e pa s.2-4 I is known ha he peculia physical and chemical p ope ies a e deeply connec ed o he mo phology and size in nanoscale o he espec i e ma e ial. Especially one-dimensional (1D) nanoma e ials, such as nanowi es and nano ubes, ha e a ac ed immense in e es , as hese aniso opic nanos uc u es a e expec ed o play an impo an ole as building blocks, in e connec s and unc ional uni s in he ab ica ion o elec onic, op oelec onic, elec ochemical and elec omechanical nanoscale de ices. The e o e, i was necessa y o de elop s aigh o wa d syn heses o hese nanos uc u es and al e hei composi ion. The in e es and demand o 1D hyb id nanoma e ials inc eased d ama ically a e hei p oduc ion became much mo e easible h ough a ious empla ing echniques and elec ospinning. Templa e-di ec ed o empla e-assis ed p oduc ion o 1D hyb id nanoma e ials became e en mo e acile when polyme ic so empla es we e used. The la ge scale p oduc ion o well-de ined polyme s and polyme ic empla es in all kinds o composi ions became a he simple due o he many imp o emen s in con olled/li ing polyme iza ion echniques. The ollowing chap e s desc ibe he syn hesis o so 1D empla es and hei use in he empla e-di ec ed syn hesis o hyb id ma e ials in mo e de ail. This hesis is dealing wi h he applica ion o so polyme ic empla es o he p oduc ion o 1D hyb id nanos uc u es. Di e en ypes o cylind ical polyme b ushes wi h well- de ined s uc u es we e p epa ed h ough di e en me hods. Fu he , hese 1D so empla es we e used o he con olled ab ica ion o 1D hyb id nanoma e ials. Chap e 1 – In oduc ion 12 1. Cylind ical Polyme B ushes Acco ding o Milne , polyme b ushes a e “long-chain polyme molecules a ached by one end o a su ace o in e ace by some means, wi h a densi y o a achmen poin s high enough so ha he chains a e obliged o s e ch away om he in e ace, some imes much a he han he ypical uns e ched size o a chain”.5 Al hough, his de ini ion was o iginally di ec ed a plana polyme b ushes wo decades ago, he quin essence s ill holds ue oday. Howe e , he e m ‘polyme b ushes’ e e s nowadays o assemblies o polyme chains, which a e a ached by one end o he su ace o a plana (2D), a sphe e (3D), a linea polyme chain o a hin polyme ic o ino ganic od (1D).6 3D polyme b ushes a e commonly e e ed o as sphe ical polyme b ushes (SPBs) whe eas 1D polyme b ushes a e usually gi en he name ‘molecula b ushes’ o a e simply called cylind ical polyme b ushes (CPBs). By de ini ion, CPBs a e o ganic 1D nanos uc u es consis ing o polyme chains ha a e densely e he ed nex o each o he . The densi y o chains o polyme molecules (g a ing densi y) is e en ually so high ha he chains become c owded and a e s e ched.7 This s e ching o a CPB can be achie ed by wo majo pa hways: i s ly, he la e al a achmen o polyme chains on o a long polyme main chain (backbone) and, secondly, he c osslinking o cylind ical domains in ei he bulk hin ilms o cylind ical micelles. Scheme 1-1 shows possible ways o syn hesize CPBs. The dense a achmen o side chains o a linea polyme backbone can be achie ed by h ee possible pa hways: (A) ‘g a ing- h ough’,8-10 (B) ‘g a ing-on o’, and (C) ‘g a ing- om’ (see Scheme 1-1A). Besides hese h ee me hods, whe e he side chains a e co alen ly linked o he backbone, he e a e se e al non-co alen app oaches. Non-co alen in e ac ions, such as coo dina ion,11 hyd ogen bonding12 and ionic in e ac ion,13,14 ha e been success ully used o bond su ac an s on o linea polyme chains o o m b ush-like a chi ec u es. Many g oups ha e syn hesized CPBs h ough he c osslinking o cylind ical domains in mic ophase-sepa a ed polyme bulk ilms (see Scheme 1-1C).15-18 Resea che s ha e also ound ways o ob ain cylind ical b ushes om wo m-like micelles by p ese ing hei shape h ough c osslinking o he cylind ical inne domain (see Scheme 1-1B).19-21 Fu he mo e, c ys alliza ion-d i en cylind ical polyme micelles we e p oduced by se e al g oups22-25 h ough c ys allizing one block o linea block copolyme s in o a cylind ical domain. Howe e , he co e o hese b ush-like micelles is no c osslinked and Chap e 1 – In oduc ion 13 he e o e is less s able ega ding ac u ing compa ed o he co e-c osslinked analogues. Howe e , i is deba able whe he he polyme b ushes de i ed om block copolyme s a e genuine CPBs o a he “b ush-like” cylinde s compa ed o he classic CPBs de i ed om he abo emen ioned g a ing app oaches. Rega dless, he s e ching o la e al polyme chains lead o many new physical phenomena, which opened many new esea ch a eas and inc eased he in e es in aniso opic polyme ic ma e ial d ama ically. Scheme 1-1. Di e en app oaches o p epa e CPBs: (A) ‘G a ing- h ough’, ‘g a ing-on o’ and ‘g a ing- om’ echniques in ol ing a s ep-wise build-up o CPBs. (B) Co e-c osslinking o cylind ical micelles in solu ion. (C) Mic o-phase sepa a ion o block copolyme s in bulk in o hexagonally packed cylinde s and he subsequen c osslinking o he cylind ical domain o p oduce CPBs a e dispe sion. 1.1 Cylind ical Polyme B ushes ia G a ing App oaches As illus a ed in Scheme 1-1A, CPBs can be syn hesized by h ee g a ing ou es, namely ‘g a ing- h ough’, ‘g a ing-on o’ and ‘g a ing- om’. One cha ac e is ic ha all h ee me hods ha e in common is ha polyme ic side chains become adhe ed e y closely nex o each o he and he la e al dimension is ela i ely small compa ed o he ac ual leng h o he main chain.26 E o s in gaining inc eased con ol o e he polyme iza ion kine ics b ough ou se e al li ing/con olled polyme iza ion echniques wi h which i became Chap e 1 – In oduc ion 14 easible o p oduce de ined CPBs wi h a ious composi ions by he ollowing g a ing me hods. ‘G a ing- h ough’ desc ibes he polyme iza ion o mac omonome s in o polyme b ushes. Mac omonome s a e polyme chains ca ying e minal polyme izable g oups.27 Since mac omonome s ha e o be p oduced sepa a ely, i is easie o con ol leng h and composi ion o he side chains. In addi ion, hey can be accu a ely cha ac e ized p io o polyme iza ion. Ano he clea ad an age o his me hod is he g a ing densi y o 100 %, as e e y epea ing uni ca ies one side chain. Despi e he excellen con ol o he composi ion and he well-de ined g a ing densi y, he ‘g a ing- h ough’ me hod bea s i s limi a ions. As polyme chains end o coil, he accessibili y o he e minal unc ionali y o mac omonome s is hampe ed. Addi ionally, s e ical hind ance and a low concen a ion o polyme izable g oups dec ease he p opaga ion o he main chain and hence limi he ac ual leng h o he backbone. Polyme iza ions o en show incomple e con e sion and consequen ly make pu i ica ion edious.28-30 Con en ional adical polyme iza ion allowes he use o a wide ange o monome s and eac ion condi ions; howe e , he ela i ely poo con ol o e molecula weigh and chain end unc ionali y p e en s he p epa a ion o well-de ined s uc u es.31 Consequen ly, many esea ch g oups ailed o p oduce poly(mac omonome s) wi h espec able backbone leng hs using di e en kinds o polyme iza ion echniques, such as anionic32-34 and ca ionic35 polyme iza ion, as well as g oup ans e polyme iza ion (GTP),29 a om ans e adical polyme iza ion (ATRP),28 and e e sible addi ion agmen a ion ans e (RAFT) polyme iza ion.36 Howe e , ing- opening me a hesis polyme iza ion (ROMP) o no bo nene end- unc ionalized polyme s enabled he syn hesis o longe polyme backbones. Whe eas he so-called ‘Sch ock ini ia o ’37 s ill did no p oduce long enough main chains,30,38 he use o me allocene- ca alyzed ROMP allowed high monome con e sion and hence esul ed in polyme b ushes wi h passable backbone leng h 39,40 and accep able leng h and molecula weigh dis ibu ion.41-44 Nex o he signi ican p og ess in he ‘g a ing- h ough’ app oach, many esea ch g oups ocused as well on de eloping ‘g a ing- om’ and ‘g a ing-on o’ echniques. The ‘g a ing-on o’ me hod in ol es a polyme main chain ha ca ies unc ional g oups on each monome uni and end- unc ional polyme chains. Bo h backbone and side chain polyme s a e p oduced sepa a ely and can be cha ac e ized p io o he polyme b ush o ma ion. The side chains a e hen g a ed on o he backbone by eac ing he pendan Chap e 1 – In oduc ion 15 unc ional g oups o he backbone p ecu so wi h end- unc ionalized polyme chains. A di e se se o echniques has been used so a o p oduce molecula b ushes by he ‘g a ing-on o’ app oach. Ini ially, many esea ch g oups ocused on using li ing anionic chain ends and quenched hem wi h sui able elec ophilic polyme backbones o ob ain comb-like polyme s o polyme b ushes.45-51 These syn he ic ou es enabled, al eady back in he ea ly 1980s, he syn hesis o many g a copolyme s. Wi h he s a o he 21s cen u y, so-called ‘click chemis y’ enabled new possibili ies ega ding he co alen a achmen o polyme ic side chains on o a p ecu so backbone. The ou ide o oday’s ‘click chemis y’ was he azide-alkyne Huisgen cycloaddi ion,52 whe e azide and alkyne g oups eac equimola o o m a iazole ing. Today, he e exis s a numbe o imp o ed o di e en click eac ions compa ed o he classic Huisgen model.53 The mos applied e sion is he coppe (I)-ca alyzed azide-alkyne cycloaddi ion (CuAAC).54,55 The di e si y, simplici y and e iciency o many click eac ions allowed he p epa a ion o polyme backbones wi h a high g a ing densi y. Biopolyme s o polyme ic backbones p epa ed by con olled adical polyme iza ion (CRP) ha e been equipped wi h clickable g oups and hen employed o syn hesize CPBs.56-58 Ano he way o p oduce molecula b ushes is o use non-co alen (seconda y) in e ac ions, such as hyd ogen bonding,12,59,60 ionic in e ac ions,14,61,62 o coo dina ion bonding.11 Independen on he way side chains a e g a ed on o a polyme backbone, he ‘g a ing- on o’ app oach has i s limi a ions ega ding g a ing e iciency. The limi a ions a ise h ough issues conce ning en opy and s e ical hind ance. As bo h he polyme backbone and he ye una ached polyme side chains exis as andom coils in solu ion, he a achmen o mo e and mo e side chains o he backbone leads o he s e ching o he backbone and acco dingly o he s e ching o he side chains - bo h a e en opically un a o ed. The cons an ly inc easing densi y o he g a ed chains also causes di icul ies o he di usion o u he chains o he eac i e si es due o s e ical hind ance. One can o e come hese issues by adding a la ge excess o he o-be-g a ed side chains, howe e , un eac ed chains will emain in solu ion a e he eac ion and equi e u he pu i ica ion s eps. Ano he way o inc ease g a ing e iciency is o dec ease he leng hs o he o-be- g a ed side chains, as his will educe s e ical hind ance.57 As a esul o he limi a ions aced in he ‘g a ing- h ough’ and ‘g a ing-on o’ me hods, he ‘g a ing- om’ app oach became he mos u ilized me hod o g a side chains o a polyme backbone. Chap e 1 – In oduc ion 22 nBA and hence only he modi ied HEMA uni s g ow side chains.107 Such g adien homopolyme b ushes unde go ans o ma ion om od-like in o adpole-like con o ma ions.110 He e og a ed copolyme b ushes ha e been syn hesized by Neugebaue e al. ia he ‘g a ing- h ough’ o mac omonome s. The mac omonome s had ei he ac yla e o me hac yla e g oups, which led o eac i i y a ios o he mac omonome s and he e o e o a g adien copolyme b ush (see Figu e 1-3C).108,109 Figu e 1-3. (A) S a is ical copolyme b ushes we e ob ained ia he ‘g a ing- h ough’ o mac omonome s and o ma ion o Janus- ype and pa chy b ushes a e qua e niza ion.100 (B) Mic ophase sepa a ion o iblock e polyme s and subsequen c osslinking was used o ob ain Janus- ype polyme cylinde s.18 (C) Copolyme iza ion o mac omonome s o di e en eac i i y was unde aken o ob ain he e og a ed g adien polyme b ushes.108 (D) A bi unc ional polyme backbone was used o he sequen ial block g ow h o poly(lac ic acid) (PLA) ia ROP and polys y ene (PS) ia ATRP o ob ain block- ype CPBs.105 Chap e 1 – In oduc ion 23 1.1.4 B anched, Mac ocyclic and Mul ig a Polyme B ushes CPBs ha e been used as building blocks o cons uc mo e complex polyme a chi ec u es, such as double-g a ed (g a -on-g a ) b ushes,89,111 cylind ical ubes,112 ba bwi es113 and lowe -like o dumbbell-like s uc u es.104,114 B anched polyme b ushes, such as dend idic polyme b ushes, ha e been p epa ed by se e al g oups ia all h ee g a ing app oaches (see Figu e 1-4C).115-120 Ano he ype o b anched b ushes a e s a - shaped b ushes. Fou o i e a m s a s we e success ully syn hesized ia a coupling o li ing anionic PS and s a -like poly(chlo oe hyl inyl e he ) (PCEVE) chains.121 By p oducing a h ee- o ou - a med s a polyme wi h ATRP ini ia o g oups as monome uni s o he a ms, i was possible o p epa e e y uni o m h ee- o ou - a med s a molecula b ushes (see Figu e 1-4A).122 Figu e 1-4. (A) S a -shaped molecula b ushes ob ained when s a -shaped p ecu so s we e used wi h an ATRP ini ia o con aining a ms, and he espec i e AFM image. 6,122 (B) The s a egy o he syn hesis o mac ocyclic copolyme b ushes using ABC iblock e polyme s and anionic li ing chain ends. Mac ocyclic b ushes (see AFM phase image) o med cylind ical ubes.112 (C) Two s a egies owa ds dend onized polyme b ushes using ei he he ‘g a ing-on o’ (‘a ach o’) ou e o he ‘g a ing- h ough’ (mac omonome ) ou e. Ded onized polyme b ushes can o m long cylinde s (see AFM image).119 Chap e 1 – In oduc ion 24 Ano he special ype o polyme b ushes a e mac ocyclic b ushes, whe e he wo ends o he b ush a e connec ed o each o he by a coupling eac ion.123 The p epa a ion o la ge mac ocyclic (co)polyme b ushes is limi ed by se e al ac o s. Fi s ly, i is di icul o ob ain only α,ω-di unc ional high mola mass p ecu so s and, secondly, he e is a d as ic dec ease in he end- o-end ing closing e iciency when he dis ance be ween he chain ends becomes oo la ge. Las ly, he sepa a ion om non-closed and s ill-linea con aminan s is di icul , as each consis s ou o compa able mola mass.124 De ieux e al. de eloped a s a egy o syn hesize la ge polyme mac ocycles which a e based on an ABC iblock e polyme .112 The iblock e polyme has a long cen al block B, which possesses wo sho blocks (A and C) on each end. Blocks A and C bea monome uni s ha eac exclusi ely wi h each o he . The ex e nal blocks a e hen selec i ely ac i a ed unde dilu e condi ions o allow in amolecula coupling be ween he A and C blocks o o m he mac ocyclic polyme s. Chlo oe hyl inyl e he was selec ed as he monome o he cen al block B, because i can be eadily de i a ized in o b ushlike polyme s by a ‘g a ing-on o’ p ocess. The co esponding mac ocyclic b ushes we e deco a ed wi h PS o andomly dis ibu ed PS and polyisop ene (PI) b anches (see Figu e 1-4B). In a selec i e sol en o he PI b anches, he mac ocyclic b ushes sel - assemble in o cylind ical ubes wi h a leng h up o se e al hund ed nanome e s.112 1.2 Cylind ical Polyme B ushes om Block Copolyme s CPBs o a he b ush-like polyme cylinde s can also be ob ained om diblock copolyme s o iblock e polyme s in ei he solu ion o bulk. The b ush o ma ion in solu ion can be achie ed by p oducing cylind ical micelles and he subsequen c osslinking o he cylind ical domain.19,125,126 As an example, Liu e al. used he diblock copolyme poly(s y ene)-block-poly(2-cinnamoyle hyl me hac yla e) (PS-PCEMA), whe e PCEMA o med he cylind ical micella co e and could be c osslinked by UV- ligh .20 In his case, he PS chains a e hen he g a s o he PCEMA od and he whole uni esembles a CPB. Schmalz e al.23 and Winnik e al.,22 as discussed abo e, used diblock o iblock polyme s wi h a c ys allizable block o o m CPBs. The c ys allizable block o med he cylind ical co e upon cooling and he e o e p ese ed he wo m-like geome y. Winnik e al. used he diblock copolyme poly( e ocenyldime hylsilane)- block-poly(isop ene) (PFS-PI) o induce c ys alliza ion o PFS in o cylinde s wi h PI g a s (see Figu e 5B). Chap e 1 – In oduc ion 25 Al e na i ely, he same ype o cylind ical b ush can also be p epa ed by he c osslinking o cylind ical mic odomains o mic ophase-sepa a ed block copolyme s in bulk. In his way, CPBs om bulk hin ilms we e achie ed by choosing he composi ion o AB diblock copolyme s o ABC iblock e polyme s in a way ha he block B would mic ophase-sepa a e in o a cylind ical mo phology.15,16,18 Fo example, i was again Liu e al. who used he pho o-c osslinkable polyme PCEMA, bu his ime hey yielded cylinde s o PCEMA dispe sed in he con inuous phase o PS in bulk. The dissolu ion o he c osslinked cylinde s esul ed in isola ed polyme b ushes wi h c osslinked PCEMA co es and PS g a s (see Figu e 1-5A).17 cylind ical micelles mic ophase-sepa a ion dispe sion Figu e 1-5. (A) PS-PCEMA diblock copolyme can be used o ei he o ming cylind ical micelles in solu ion o PCEMA cylinde s in a PS ma ix in bulk. In each case, PCEMA can be c osslinked by UV-ligh and yield PCEMA cylinde s wi h PS g a s.15,20 (B) PFS-PI diblock copolyme s we e used o unde go c ys alliza ion. The eby, PFS o med cylinde s whe eas he PI block p oduced he g a s.22 Chap e 1 – In oduc ion 26 1.3 P ope ies o Cylind ical Polyme B ushes The con o ma ion o CPBs is a esul o compe ing o ces be ween he backbone and he g a s. The densely g a ed side chains epel each o he , bu hei abili y o mo e apa is hampe ed by he backbone, which locally con ines he side chains o a cylind ical olume. Consequen ly, cylind ical b ushes may exhibi di e en con o ma ions on di e en leng h scales.127,128 In ensi e esea ch has been pe o med o highligh he unique p ope ies o CPBs. CPBs a e s uc u ally mo e compac when compa ed o he co esponding linea polyme s o he same molecula weigh . This compac ness de i es om a highe densi y o chain segmen s. The s e ic epulsion o densely g a ed side chains esul s in an ex ended wo m-like con o ma ion. The ex en o backbone s e ching is mos ly dependen on he side chain leng h and he na u e o he sol en used. The ex ended wo m-like con o ma ion makes i di icul o cha ac e ize CPBs wi h con en ional cha ac e iza ion echniques, such as size exclusion ch oma og aphy (SEC), dynamic o s a ic ligh sca e ing (DLS and SLS) o iscome y. Cha ac e iza ion becomes e en mo e p oblema ic when he composi ion o CPBs is he e ogeneous. The e o e, se e al ypes o scanning p obe mic oscopies ha e been es ablished and a e nowadays equen ly used in he cha ac e iza ion o CPBs. The mos equen ly used ype is AFM, as i is a powe ul ool and allows he p ecise imaging o CPBs and he cha ac e iza ion o hei molecula weigh , size and con o ma ion.82,129-131 The e ha e been many scien i ic s udies on he p ope ies o CPBs in solu ion, on su aces and in bulk. 1.3.1 Solu ion P ope ies As men ioned abo e, he cylind ical shape o CPBs de i es om he epulsion o side chains ha a e e he ed e y densely on o a polyme backbone. In solu ion, CPBs adop he con o ma ion o a wo m-like objec ha can be cha ac e ized by he leng h pe monome lm, he b ush diame e D, and he pe sis ence leng h lp. Ob iously, hese pa ame e s, and hence he cylind ical dimensions, depend on g a ing densi y, side chain leng h and sol en na u e. Many heo e ical,61,132-134 simula ion135-141 and expe imen al31,142-146 s udies ha e been pe o med o lea n abou side chain e ec s, sol en e ec s and main chain con o ma ions. Howe e , opinions and esul s di e as o how much chain side leng h is c ucial o lp and he o e all b ush s uc u e. Fo example, Chap e 1 – In oduc ion 27 o lexible side chains, i is heo e ically p edic ed ha a s i ening o he backbone is no su icien o cause o de ing o CPBs,128 bu expe imen s show hexagonal o de ing o cylinde s ha s i ened wi h inc easing side chain leng h.147,148 A u he p ope y o CPBs is ha hey can ac as liquid c ys als and, he e o e, o m a lyo opic phase when concen a ed in solu ion (see Figu e 1-6A).78,149 When a h eshold concen a ion is exceeded, he polyme side chains will in e pene a e and hence show o de ing. Th eshold concen a ions depend s ongly on he leng h o he side chains. Ano he in e es ing solu ion p ope y o CPBs is ha hey can espond easily o en i onmen al changes and change hei mo phology acco dingly. Thei mo phology, as well as hei lexibili y, is mainly di ec ed by sol en quali y, which in wa e depends on sal concen a ion, su ac an s, empe a u e and pH. I is possible o igge sha p ansi ions in he mo phology o CPBs. This makes hem an in e es ing ma e ial o a ious applica ions, such as memb anes o senso s. CPBs consis ing o he mo- esponsi e polyme s, such as poly(2-(dime hylamino)e hyl me hac yla e) (PDMAEMA) o poly(N-isop opylac ylamide) (PNIPAM) a e classical examples whe e he cylind ical shape will collapse upon hea ing abo e a ce ain empe a u e.77,150,151 Fu he , PDMAEMA polyme b ushes a e esponsi e o pH151,152 and sal (see Figu e 1-6C).152 PDMAEMA loses i s esponsi eness o pH and empe a u e upon qua e niza ion due o he pe manen cha ge; howe e , i s ays sensi i e o sal s. Cha ged CPBs like poly{[2- (me hac yloyloxy)e hyl] ime hylammonium iodide} (PMETAI) can also be used o he o ma ion o in e polyelec oly e complexes (IPECs) wi h opposi ely cha ged polyions, such as poly(s y enesul ona e) (PSS).153 Chap e 1 – In oduc ion 28 sal - esponsi epH- esponsi e b) a) Figu e 1-6. (A) [(SiO)1.5-OEGMA]3200 co e-shell CPBs wi h a pa ially ino ganic co e a e a he s i in solu ion (see c yo-TEM) and o m (a) iso opic and (b) lyo opic phases upon concen a ing.78 (B) Simula ed esul s o he in e ac ion o cha ged CPBs and su ac an s. Depending on he s i ness o he backbone, he main chain can adop a ious con o ma ions om s i cylinde s o sphe es.140 (C) DLS demons a es ha PDMAEMA b ushes show pH- esponsi eness and a e sal - esponsi e a e qua e niza ion. AFM s udies highligh he collapsed sphe ical s uc u es a e he inc ease o sal concen a ion o sodium b omide (NaB ).152 The solu ion p ope ies o he e ogeneous b ushes, such as co e-shell b ushes a e conside ably mo e complica ed. Bo iso e al. ha e epo ed ha he shape o co e-shell b ushes can be e y di e en depending on he sol en quali y o he co e and he shell (see Figu e 1-2D).97 1.3.2 Cylind ical Polyme B ushes on Su aces and in he Bulk Simila o he solu ion p ope ies, whe e he b ushes beha e acco ding o he en i onmen and changes he ein, polyme b ushes end o beha e di e en ly acco ding o he in e ac ion be ween he indi idual blocks, he unde lying subs a e and he su ounding en i onmen .127 Figu e 1-7A shows possible mo phologies o co e-shell CPBs on a subs a e. Depending on he s eng h o he adso p ion and he b ush a chi ec u e, i is Chap e 1 – In oduc ion 29 possible ha molecula b ushes unde go associa ion and dissocia ion du ing hei adso p ion on he subs a e.154 PnBA b ushes associa e due o he c ys alliza ion o he linea poly(oc adecyl me hac yla e) chains on bo h ends o he b ush backbone. A mo e in iguing phenomenon is he scission o polyme b ushes on subs a es. Long CPBs wi h long side chains may unde go scission o he backbone upon he adso p ion on o a subs a e, such as g aphi e o mica.155 Di e en incuba ion imes e i ied he p oceeding scission o polyme b ushes in o sphe e-like b ush agmen s (see Figu e 1-7C). The mac omolecula des uc ion o igina ed om side-chain-induced s e ching o he polyme backbone o maximize he numbe o con ac s wi h he subs a e. Mo eo e , CPBs can be used o s udy he mo ion and low o molecules.156,157 I is u he possible o o de molecula b ushes du ing sp eading. Flow-enhanced di usion o mac omolecules esul ed in epi axial alignmen o mac omolecules, whe e he o ien a ion was independen o he low di ec ion.158 In bulk, CPBs beha e di e en ly as compa ed o linea polyme chains. CPBs can be used o p oduce new ma e ials wi h unusual mechanical p ope ies. Molecula b ush backbones a e less en angled in bulk due o he la ge ac ion o densely g a ed side chains. This sel -disen anglemen esul s in unique iscoelas ic p ope ies, which depend on bo h he leng h o he main chain (backbone) and he side chains. T ans o ma ion o he b ush ilms in o c osslinked ne wo ks p oduced a high local mobili y and su icien mac oscopic mechanical s abili y.111,159-161 The esul ing class o ma e ials a e e med (supe -) so elas ome s. Rzaye e al. u he epo ed he phase-sepa a ion o block- ype PS-PLA polyme b ushes analogue o linea block copolyme s.105,162 Consequen ly, i was possible o ob ain a cylind ical bulk mo phology om CPBs o he i s ime. A e deg ada ion o he cylinde - o ming PLA block, a nanopo ous polyme ne wo k was p oduced (see Figu e 1-7B). The same PS-PLA polyme b ush was used o con olled e apo a i e sel -assembly o hie a chically s uc u ed bo leb ush block copolyme s (see Figu e 1-7D).163 In a special e apo a ion p ocess, a oluene solu ion o he PS-PLA block copolyme b ushes was aligned in g adien s ipes wi h in e nal lamella nanodomains. Chap e 1 – In oduc ion 30 Figu e 1-7. (A) Possible mo phologies adop ed by co e-shell CPBs on di e en subs a es.127 (B) Phase- sepa a ed PS-PLA block- ype CPBs, which o m a nanopo ous ne wo k a e PLA cylinde deg ada ion.162 (C) Scission o long polyme b ush backbones wi h long side chains.155 (D) Hie a chical s uc u ing o block- ype CPBs in o g adien lines wi h in e nal lamella phase-sepa a ion.163 1.4 Applica ions o Cylind ical Polyme B ushes The many di e en p ope ies and high unc ionali ies, oge he wi h he o en s aigh o wa d syn heses, ende CPBs use ul ools o a ple ho a o applica ions in all kinds o ields o physics, chemis y, biology and ma e ial sciences. The 1D shape and he mul iple, concen ic and indi idually sepa a ed compa men s make CPBs sui able o be used as deli e y ehicles o empla es. The ollowing sec ions highligh he e sa ile applica ions o CPBs and hei use as nanosized building blocks o he ab ica ion o hie a chically s uc u ed 1D ma e ials. No only can CPBs be used o isualize and demons a e molecula p ocesses,155,164 bu mo e so, hey can be used in medical and biological applica ions, such as po en ial d ug deli e y ehicles o gene ans ec ion. Cell en y is dependen on he shape o he deli e y ehicles.165 I is epo ed ha he cell en y o 1D nanoma e ials occu s by ip ecogni ion and o a ion,166 and ha a cylind ical shape is ad an ageous ega ding he e en ion ime Chap e 1 – In oduc ion 31 in he body.167 Acco dingly, G ubbs e al. ecen ly epo ed he syn hesis o d ug loaded CPBs, whe e he d ug can be eleased upon deg ada ion o a linking g oup (see Figu e 1- 8).42,168 Figu e 1-8. (A/B) No el 1D d ug deli e y ehicles de eloped ia he ‘g a ing- h ough’ o unc ional and d ug-con aining bi alen mac omonome s.42,168 Aside om he biological applica ions, CPBs o en ind use as empla e ma e ials o he p epa a ion o o ganic/ino ganic hyb id nanoma e ials. Among he di e en s uc u es, co e–shell CPBs a e o special in e es because hey can be u ilized in he syn hesis o cylind ical hyb id nanos uc u es, such as nanowi es and nano ubes, wi h in e es ing p ope ies a e me alliza ion o o he modi ica ion. The ollowing sec ion ocuses on empla e-di ec ed syn heses o 1D hyb id nanos uc u es, in which CPBs play an signi ican ole in he bo om-up p ocesses. Chap e 1 – In oduc ion 38 cha ac e is ics o a li ing p ocess.24,203 Hence, i was possible o g ow block- ype cylind ical micelles whe e only a ce ain block we e hyb idized in a con olled way.24 2.1.3 Sel -Assembled One-Dimensional Templa es om Bulk As illus a ed abo e, block copolyme s can be used as so empla es as hey can o m 1D nanos uc u es in solu ion due o hei di e en o incompa ible blocks. The incompa ibili y o blocks is a necessi y o he mic o-phase sepa a ion o block copolyme s in hin ilms. Phase-sepa a ed block copolyme s ha e been s udied ex ensi ely o he ab ica ion o hyb id and ino ganic ma e ials.204-207 Diblock copolyme s can phase-sepa a e in o a cylind ical mo phology, as illus a ed in Scheme 1- 1C, and can be used as 1D so empla es a e c osslinking o he cylind ical domain. Templa e CPBs om PB-P2VP we e used o p oduce polyoxome ala e nanos uc u es a e loading he P2VP co ona wi h opposi ely cha ged [SiMo12O40]4- Keggin ions (see Figu e 1-12A).175 Chen e al. used silicon con aining and gel-able monome s o syn hesize block copolyme s whe e he c osslinked silsesquioxane (SiO1.5) p oduc s hemsel es can be conside ed as hyb id ma e ials. SiO1.5 nanowi es and ubes ha e been p epa ed om bulk hin ilms.208-210 Poly(3-( ie hoxysilyl)p opyl me hac yla e)-block- poly(2- inylpy idine) (PTEPM-P2VP) was used o he syn hesis o SiO1.5 nanowi es wi h a P2VP shell, which we e used in a subsequen s ep o immobilize gold nanopa icles wi hin he shell.210 SiO1.5 nano ubes we e ob ained in he case o an ABC iblock e polyme whe e he middle block B consis ed ou o PTEPM.208 Depending on he p epa a ion o he bulk ilm, block A (PS) could be he ou e co ona and block C (P2VP) could be in he co e, o ice e sa (see Figu e 1-12B). P2VP was again used o u he immobiliza ion o nanopa icles.208 The concep o ABC iblock e polyme s phase sepa a ion was also applied by Liu e al. o ob ain polyme ic nano ubes whe e he ube- o ming block B (PCEMA) was pho o- c osslinkable .211-215 Depending on he co e- o ming polyme block, a ious 1D hyb id nanos uc u es we e syn hesized. In he case o a PAA co e, Yan e al. p oduced wa e - dispe sible polyme /Pd/Ni hyb id magne ic nano ibe s by sequen ial illing o he co e wi h Pd and Ni.213 They u he epo ed γ-Fe2O3 hyb id magne ic nano ibe s ollowing a simila p ocedu e.211 Chap e 1 – In oduc ion 39 a) b) a) Figu e 1-12. (A) The syn he ic s a egy o he ab ica ion o Keggin ion nanos uc u es, including a SEM image o he hyb id nano ibe s.175 (B) The sel -assembly o ABC iblock e polyme s ha con ain a gel- able middle block can o m (a) nano ubes in bulk hin ilms. (b) Nano ubes wi h a P2VP co e we e illed wi h gold nanopa icles.208 2.1.4 Biological and O he One-Dimensional Templa es Polyme ic so empla es need o be shaped in o 1D mo phology by expe imen al e o s. Howe e , na u e p o ides al eady p e-exis ing 1D nanos uc u es ha can be used o empla e chemis ies. Typical examples o biological nanos uc u es ha consis o building blocks ha a e aligned one-dimensionally a e cellulose,216 collagen,217 DNA218- 222 and a ious i uses.223-227 The mos amous so empla e is he obacco mosaic i us (TMV), which is e y uni o m in leng h and diame e . TMV was, o example, used o syn hesize CdS, SiO2 and TiO2 nanowi es (see Figu e 1-13A).225,227 Nex o TMV, DNA o en inds use as a empla e ma e ial. Co nanowi es we e g own on Pd nanopa icles seeded DNA.228 Simila o biological sys ems, he e a e o he 1D nanos uc u es ha can be applied in empla e-assis ed and empla e-di ec ed hyb idiza ion eac ions. Cu en ly exis ing ino ganic, o ganic and e en hyb id 1D objec s a e use ul as empla es in hei unmodi ied s a es. The mos equen ly used among he many a ailable 1D s uc u es a e ca bon nano ubes (CNTs). Thei s aigh o wa d unc ionaliza ion led o nume ous wo ks on Chap e 1 – In oduc ion 40 polyme -coa ed CNTs.229-231 These polyme coa ings can hen again be used o hyb idiza ion. Fo example, gold nanopa icles we e a ached o poly(diallyl- dime hylammonium)chlo ide (PDADMAC) co e ed CNTs (see Figu e 1-13B).232 PDMAEMA-co e ed mul i-walled CNTs (MWCNTs) we e able o be used o he syn hesis o wo m-like silica nano ubes.233 O he 1D objec s, such as nickel nano ods, we e applied in se e al s a egies o ob ain hyb id ma e ials.193,234 Pb(II)/ H 2 S Cd(II)/ H 2 S TEOS Fe(II)/ Fe(III) Gold Colloids Figu e 1-13. (A) TMV was used o p oduce a ious 1D hyb id ma e ial, such as CdS nanowi es (see TEM mic og aph).225 (B) PDADMAC-co e ed CNTs we e used o align gold nanopa icles in o a 1D manne (see TEM mic og aph).232 2.2 Po ous Memb ane-Based Templa es The use o po ous memb anes, such as AAO, ack-e ched polyca bona e memb anes o mesopo ous silica, ga e ise o simple and s aigh o wa d me hods o he p epa a ion o 1D nanoma e ials. The main ad an age o such po ous empla es wi h cylind ical po es is he supe io uni o mi y o po e diame e s, which can be adjus ed du ing he p epa a ion me hod. Many 1D ma e ials ha e been syn hesized, including me als,235 oxides,236 semiconduc o s237 and polyme s.235 The p ocess o illing he po es is highly a iable and can be easily con olled, which consequen ly allows he syn hesis o e y complex nanos uc u es. Howe e , when compa ed o he abo emen ioned so empla ing echniques, i is qui e di icul o ob ain la ge amoun s o ma e ials om such app oaches. 2.3 Elec ospinning Elec ospinning is no a empla ing echnique pe se; howe e , i should be men ioned as i is a highly e sa ile me hod o he p oduc ion o 1D hyb id ma e ials. Wi h elec ospinning, i became possible o syn hesize ul a- hin nanowi es o nano ibe s. F om many polyme mel s o solu ions, ibe s ha e been p oduced ia elec ospinning p ocesses. By adding ino ganic ma e ials o p ecu so s in o he mel s and mix u es, hyb id nanoma e ials o de ined hickness ha e been ob ained, ei he di ec ly o a e a Chap e 1 – In oduc ion 41 subsequen s ep. Combined wi h sol-gel chemis y, many polyme -me al oxide hyb id ibe s ha e been syn hesized by elec ospinning, such as poly( inylpy olidone)/TiO2 (PVP/TiO2) o PVP/Z O2 hyb ids.238 Fu he mo e, ino ganic ma e ials, like ZnO239,240 o CdS241, ha e been blended in o polyme ic nano ibe s. G eine e al. used elec ospun PLA ibe s as empla es o he ab ica ion o TiO2 and Pd ubes 242,243 3. Aim o he Thesis The mo i a ion o his wo k was o b oaden he applica ion ange o CPBs as empla es o he p epa a ion o no el 1D polyme -ino ganic hyb id nanoma e ials. I was in ended ha molecula co e-shell o co e-shell-co ona CPBs, plus CPBs ob ained h ough mic ophase sepa a ion o diblock copolyme s, be used o he syn hesis o new 1D hyb id ma e ials. Co e-shell-co ona CPBs con aining a gelable shell block we e o be syn hesized in o de o di ec ly inco po a e he ino ganic pa in o he polyme b ush s uc u e. This would be a no el way o syn hesizing uni o m hyb id nano ubes. Co e-shell(-co ona) CPBs wi h a deg adable co e we e o be syn hesized o he p oduc ion o hollow ino ganic nanoma e ials wi h high aspec a ios. Hollow/po ous nanos uc u es om silica o i ania we e o pa icula in e es , as hey can be used as ca ie sys ems (SiO2) o in pho o ol aic applica ions and ca alysis (TiO2). Mesoscopic polyelec oly e co e-shell CPBs we e o be designed o he hie a chical 1D s uc u ing o me al oxide nanopa icles. I was in ended ha hese new ma e ials, which a e in e es ing o pho o ol aic applica ions and ca alysis, be achie ed by he syn hesis o aniso opic c ys alline TiO2 nanos uc u es. Chap e 1 – In oduc ion 42 Re e ences (1) Liang, H.-W.; Liu, S.; Yu, S.-H. Ad . Ma e . 2010, 22, 3925-3937. 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Y.; Hayhu s , A.; Geo giou, G.; I e son, B.; Belche , A. M. Science 2004, 303, 213-217. (224) Fonobe o , V. A.; Balandin, A. A. Nano Le . 2005, 5, 1920-1923. (225) Shen on, W.; Douglas, T.; Young, M.; S ubbs, G.; Mann, S. Ad . Ma e . 1999, 11, 253-256. (226) Dang, X.; Yi, H.; Ham, M.-H.; Qi, J.; Yun, D. S.; Ladewski, R.; S ano, M. S.; Hammond, P. T.; Belche , A. M. Na . Nano. 2011, 6, 377-384. Chap e 2 – O e iew o he Thesis 54 Table 2-2. Templa e co e-shell-co ona CPBs wi h di e en dimensions. Name Composi iona Shell diame e b Templa e b ush 1 [CL14-b-DMAEMA40-b-OEGMA65]7500 23 ± 2 nm Templa e b ush 2 [CL 14 -b-DMAEMA 150 -b-OEGMA 240 ] 7500 39 ± 2 nm a Composi ion as de e mined by 1H-NMR. b Shell diame e a e TALH in il a ion. The loading o he PDMAEMA shell was pe o med in a wa e /e hanol mix u e by he d op-wise addi ion o i anium(IV) bis(ammonium lac a e) dihyd oxide (TALH). TALH is nega i ely cha ged and he e o e immobilizes only in o he PDMAEMA shell compa men , whe eas he POEGMA co ona canno complex TALH and emained unloaded. The nega i ely cha ged i ania p ecu so complexed exclusi ely wi h he amino g oups o PDMAEMA, o ming concen ic TALH nano ubes. Fu he mo e, TALH shows supe io s abili y in aqueous solu ion a oom empe a u e, compa ed o o he i ania p ecu so s, like i anium(IV) bu oxide, which hyd olyze a he apidly in he p esence o wa e and hence can also deposi in undesi ed egions, such as he co ona. The illing o he empla e b ush wi h ino ganic ma e ial was documen ed by AFM measu emen s. Filled and hyd olyzed empla e b ushes showed a signi ican inc ease in heigh as compa ed o he un illed and p is ine CPBs (see Figu e 2-3). 50 100 150 200 250 300 350 0 3 6 9 12 15 Heigh [nm] Wid h [nm] 60 90 120 150 180 210 240 0.0 0.5 1.0 1.5 Wid h [nm] Heigh [nm] Figu e 2-3. (A) [CL14-b-DMAEMA40-b-OEGMA65]7500 co e-shell-co ona CPBs we e in il a ed wi h TALH and p oduced (B) ana ase nano ubes a e hyd olysis and condensa ion. The heigh o p is ine CPBs was 1.5 nm and inc eased o 15 nm o he ana ase nano ubes. Chap e 2 – O e iew o he Thesis 55 The illing o he empla e b ushes esul ed in e y de ined TiO2 hyb id nano ubes a e hyd olysis and condensa ion. TALH gua an eed s abili y upon hyd olysis du ing he loading o he empla e a ambien empe a u es. Only abo e 70 °C, TALH hyd olyzed he mally and c ys allized in o ana ase. C yo-TEM and g ey-scale analysis illus a ed he ubula mo phology o he hyb id nanos uc u es. TEM mic og aphs highligh ed he uni o m hickness o he nano ubes, which could be adjus ed by he leng h o he PDMAEMA side chains (see Figu es 2-4 B and C). The amoun o TiO2 wi hin he hyb id nano ubes was de e mined by he mog a ime ic analysis (TGA). TGA e ealed ha longe PDMAEMA side chains inc eased he loading capaci y o he empla e (see Figu e 2-4 F). High esolu ion TEM (HR-TEM) and powde X- ay di ac ome y (PXRD) e i ied he high c ys allini y o he ana ase hyb id nano ubes (see Figu es 2-4 D and E). Scanning elec on mic oscopy (SEM) highligh ed he uni o m diame e o he hyb id nano ubes be o e and a e py olysis (see Figu e 2-5). Figu e 2-4. (A) C yo-TEM and (B) TEM mic og aphs o ana ase nano ubes om empla e b ush 1. (C) TEM mic og aph o ana ase nano ubes om empla e b ush 2. (D) HR-TEM mic og aph o a highly c ys alline ana ase nano ube. (E) PXRD o ana ase nano ubes. (F) TGA o he hyb id nanos uc u es. Chap e 2 – O e iew o he Thesis 56 Figu e 2-5. SEM images o hyb id nano ubes om (A) b ush empla e 1 and (B) b ush empla e 2. (C) Calcined hyb id nanos uc u es om empla e b ush 2. In conclusion, ou empla ing s a egy owa ds c ys alline ana ase nano ubes has p o ed o be e y e ec i e and e sa ile in p oducing well-de ined hyb id nanoma e ials. The co e-shell-co ona empla e b ushes p o ided excellen solubili y in a ious media and p e en ed c osslinking du ing hyd olysis and condensa ion. Highly c ys alline 1D TiO2 nanoma e ials we e ob ained, which may se e use ul as ca alys s o in pho o ol aic applica ions. 2.3 Silica Nanowi es and Nano ubes Silica-based ma e ials a e a ac i e ma e ials due o hei chemical ine ness, co osion esis ance, and mechanical and he mal s abili y. In his chap e , we used co e-shell CPBs as unimolecula so empla es o he syn hesis o 1D silica hyb id nanos uc u es (see Scheme 2-3). Th ough he combina ion o anionic polyme iza ion, ROP and ATRP, we p oduced co e- shell CPBs wi h a deg adable co e (namely, PCL) and a polyelec oly e shell (namely, PDMAEMA). The PCL co e also ac ed as a space o he ini ia ion si es o ATRP and he eby inc eased he g a ing e iciency o PDMAEMA o 90 % compa ed o 50-70 % o PBIEM, as epo ed in li e a u e.1-3 These unimolecula empla e b ushes we e hen used o he p oduc ion o pu e hyb id silica (see Scheme 2-3 i ) o nanopa icle-doped hyb id silica nanos uc u es (see Scheme 2-3 i). By a ying he DPn o he backbone and he side chains and consequen ly he dimensions o he empla e b ush (see AFM images in Figu e 2-6 A and D), we adjus ed he dimensions o he la e silica nanos uc u e, i.e. he hickness o he co e and he shell (see Figu e 2-6). Chap e 2 – O e iew o he Thesis 57 Scheme 2-3. Schema ic illus a ion o he empla e build-up achie ed by combining mul iple polyme iza ion echniques. (i) PHEMA was ‘g a ed- om’ ia ROP o ε-cap olac one and ATRP o DMAEMA o p oduce a (ii) co e-shell CPB. The empla e b ush was hen in il a ed wi h (iii) silica o ( ) me al sal s (such as AuCl4- o P Cl42-), ( i) p io o silica in il a ion in o he shell. (i ) Calcina ion o acid ea men p oduced hollow silica nano ubes. Figu e 2-6. AFM heigh images o empla e b ushes (A) [CL25-b-DMAEMA76]2700 and (D) [CL14-b- DMAEMA43]7500. TEM mic og aphs o 1D silica hyb id nanos uc u es om empla e b ushes (B, b) [CL10- b-DMAEMA58]2700, (C, c) [CL25-b-DMAEMA76]2700, (E, e) [CL14-b-DMAEMA43]7500 and (F, ) [CL14-b- DMAEMA342]7500. Chap e 2 – O e iew o he Thesis 58 Consequen ly, we ob ained a ious 1D silica hyb ids o a ious empla e b ushes (see Table 2-3). Sho PDMAEMA side chains ga e smoo h silica hyb id nanos uc u es. Wi h inc easing leng h o he PDMAEMA side chains, he hyb id nanos uc u es became mo e and mo e ‘hai y’, as longe side chains ended o o m bundles and h eads upon silica deposi ion (see Figu e 2-6 E and F). Table 2-3. 1D silica hyb ids wi h di e en dimensions (in nm) Templa e composi iona Templa e leng hb Hyb id leng hc Co e diame e c Silica shell diame e c [CL10DMAEMA58]2700 295 ± 20 270 ± 15 5-6 ~25 [CL25DMAEMA76]2700 265 ± 20 235 ± 20 10-12 ~35 [CL14DMAEMA43]7500 1250 ± 200 950 ± 350 6-7 ~25 [CL14DMAEMA342]7500 1250 ± 200 950 ± 350 d 6-7 e ~ 85 a De e mined by 1H-NMR; b measu ed om AFM images o he empla e b ushes; c measu ed om TEM mic og aphs o he as-syn hesized silica hyb ids; d es ima ed om TEM mic og aphs, as i was a he di icul o di ec ly measu e he ac ual leng h due o he jamming o hai y silica nanos uc u es; e assumed o be he same dimension as wi h [CL14DMAEMA43]7500; aking in o accoun ha he co e is ~6 nm in diame e . SEM images highligh he ne wo k-like s uc u es o he d ied hyb id ma e ials (see Figu e 2-7). The 1D nanos uc u es ended o pack close as he aspec a io dec eased. The ma e ial qui e esembled he s uc u e o common il e sys ems. Calcina ion o ea men wi h an acid led o he emo al o he co e and esul ed in hollow silica nanos uc u es. Figu e 2-7. SEM images o 1D silica hyb id nanos uc u es om empla e b ushes (A) [CL10-b- DMAEMA58]2700, (B) [CL14-b-DMAEMA43]7500 and (C) [CL14-b-DMAEMA342]7500. We u he embedded ca aly ically ac i e me al nanopa icles (NPs) in o he shells o he aniso opic nanoma e ials o ob ain ca aly ically ac i e nanoma e ials. Figu e 2-8 shows TEM mic og aphs o NP-doped nanos uc u es. Gold and pla inum NPs a e isible wi hin he silcia shell. The educ ion o 4-ni ophenol o 4-aminophenol by NaBH4 in he p esence o he me al NP-doped silica nanoma e ials was pe o med o demons a e he Chap e 2 – O e iew o he Thesis 59 accessibil y and he ac i i y o he ca aly ically ac i e ma e ial. Thus, he inco po a ion o ca aly ically ac i e NPs ende s e y obus ca ie s o ca alys s, which can be easily emo ed om he sys em a e he eac ion. Addi ionally, he embedmen o me allic NPs in o silica allows he s uc u es o be used in high empe a u e applica ions. This ma e ial migh also be in e es ing in he applica ion o ca aly ically ac i e il e sys ems. Figu e 2-8. TEM mic og aphs o (A) a silica hyb id doped wi h Au NPs om empla e b ush [CL14-b- DMAEMA342]7500 and (B) a silica hyb id doped wi h P NPs om empla e b ush [CL14-b-DMAEMA43]7500. 2.4 Mesos uc u ing o TiO2 Nanoc ys als in o One-Dimensional Nanos uc u es 1D nanos uc u es o me al oxides ha e been unde close in es iga ion due o hei size- dependen op ical and elec onical p ope ies, which allow hem o be used in ca alysis, sepa a ion o pho o ol aic applica ions. In his chap e , we demons a e a highly applicable syn hesis concep applied o s uc u ing me al oxides in o 1D hyb id nanos uc u es by a empla e-di ec ed app oach. 1D polyelec oly e empla e b ushes we e p oduced om a polys y ene-b-poly(allyl me hac yla e) (PS-b-PAMA) diblock copolyme , which was ob ained by sequen ial anionic polyme iza ion wi h na ow molecula weigh dis ibu ion. Mic ophase sepa a ion o he diblock copolyme in bulk esul ed in hexagonally packed PAMA cylinde s wi hin a PS ma ix. A e pho o- c osslinking o he PAMA cylinde s and e-dispe sion o he bulk ilm in THF, cylind ical polyme b ushes we e ob ained. The PS co ona was mildly sul ona ed in a subsequen s ep o ans o m he PS in o poly(s y enesul onic acid) (PSS) and ende he co ona wa e -soluble (see Scheme 2-4 ii and iii). Chap e 2 – O e iew o he Thesis 60 Scheme 2-4. (i) Diblock copolyme PS-PAMA mic ophase-sepa a ed in o hexagonally packed cylinde s. (ii) UV-c osslinked PS-PAMA cylind ical polyme b ushes a e edispe sed and (iii) sul ona ed in o polyelec oly e b ushes wi h a PSS co ona. (i ) Posi i ely cha ged and p e-syn hesized TiO2 nanoc ys als a e in il a ed in o he PSS co ona o p oduce ( ) aniso opic and c ys alline TiO2 nanowi es. The s ongly anionic polyelec oly e b ushes (see Figu e 2-9 A) we e hen used as empla es o he ab ica ion o c ys alline 1D TiO2 nanos uc u es by in il a ion o opposi ely cha ged TiO2 nanoc ys als in o he polyelec oly e co ona. The nanoc ys als we e p oduced sepa a ely p io o he o ma ion o he hyb id. We could adjus he c ys allini y o he nanoc ys als o ei he u ile o an ase by using di e en acids o he hyd olysis o he i ania p ecu so . Phase pu i y o he c ys alline colloids was con i med ia PXRD. Thei appa en hyd odynamic diame e was ei he 8 nm ( u ile) o 14 nm (ana ase), as de e mined by dynamic ligh sca e ing. Figu e 2-9. (A) C yo-TEM mic og aph o PSS-PAMA empla e b ushes in wa e . (B/C) TEM mic og aphs o as-syn hesized 1D u ile nanos uc u es. SEM mic og aphs o (D) as-syn hesized u ile nanowi es and (E) calcined u ile nanowi es. D op-wise addi ion o a empla e b ush suspension o a pa icula amoun o he espec i e nanoc ys al suspension a 60 °C and pH 1 esul ed in highly c ys alline hyb id nanos uc u es (see Figu e 2-9). The hyb id nanowi es adop ed he same c ys allini y as he in il a ed nanoc ys als, as con i med by PXRD (see Figu es 2-10 A and D). Chap e 2 – O e iew o he Thesis 61 Fu he mo e, HR-TEM highligh s he high c ys allini y o he hyb id nanos uc u es (see Figu es 2-10 B and E). Figu e 2-10. (A and D) PXRD pa e ns o c ys alline TiO2 p ecu so s ( ed pa e n) and as-syn hesized TiO2 hybi d nanoma e ials (black pa e n). HR-TEM mic og aphs and SAED pa e n o (B and C) highly c ys alline u ile and (E and F) ana ase hyb id nanowi es. N2 physiso p ion measu emen s showed a high su ace a ea o 66 m2·g-1 o he u ile hyb id nanowi es. The hyb ids o med po ous non-wo en ne wo ks upon d ying (see Figu e 2-9 D), which leads o he assump ion ha he nanowi es a e s ill qui e lexible. TGA suppo s he assump ion, as i con i med ha he u ile hyb id nanoma e ial consis s o a ound 50 w % so polyme ic ma e ial. In conclusion, we ha e de eloped a mild and gene ally applicable me hod o mesos uc u e me al oxides in o 1D hyb id nanos uc u es. The empla e-di ec ed syn hesis o 1D hyb id nanoma e ials ia cylind ical polyelec oly e b ushes was demons a ed on i ania polymo phs, bo h u ile and ana ase, which we e selec i ely mesos uc u ed in o hyb id nanowi es. Chap e 2 – O e iew o he Thesis 62 2.5 Indi idual Con ibu ions o Join Publica ions The esul s p esen ed in his hesis we e ob ained in collabo a ion wi h o he s, and ha e been published o submi ed o publica ion as indica ed below. In he ollowing, he con ibu ions o all he co-au ho s o he di e en publica ions a e speci ied. The as e isk deno es he co esponding au ho (s). Chap e 3 This wo k is published in he Jou nal o he Ame ican Chemical Socie y 132, 16587- 16592 (2010) unde he i le: “Wa e -Soluble O gano-Silica Hyb id Nano ubes Templa ed by Cylind ical Polyme B ushes” by Ma kus Müllne , Jiayin Yuan, S ephan Weiß, And eas Wal he , Melanie Fö sch, Ma kus D echsle , and Axel H. E. Mülle * I conduc ed all expe imen s and w o e he publica ion, excep ha : • S. Weiß was in ol ed in ea ly expe imen s du ing a lab cou se; • Wal he was in ol ed in discussions; • M. Fö sch and M. D echsle pe o med he c yo-TEM measu emen s; and • J. Yuan and A. H. E. Mülle we e in ol ed in scien i ic discussions and co ec ing he publica ion. Chap e 4 This wo k will be submi ed unde he i le: “Templa e-Di ec ed Mild Syn hesis o Ana ase Hyb id Nano ubes wi hin Cylind ical Co e-Shell-Co ona Polyme B ushes” by Ma kus Müllne , Thomas Lunkenbein, Ma in Schiede , Nobuyoshi Miyajima, Melanie Fö sch, Jose B eu, F ank Ca uso,* and Axel H. E. Mülle * I conduc ed all expe imen s and w o e he manusc ip , excep ha : • M. Schiede and T. Lunkenbein bo h pe o med SEM and PXRD measu emen s; • N. Miyajima pe o med he HR-TEM measu emen s; • M. Fö sch pe o med he c yo-TEM measu emen s; and • J. B eu, F. Ca uso and A. H. E. Mülle we e in ol ed in co ec ing he manusc ip . Chap e 2 – O e iew o he Thesis 63 Chap e 5 This wo k has been published in Chemis y o Ma e ials unde he i le: “Templa e-Di ec ed Syn hesis o Silica Nanowi es and Nano ubes om Cylind ical Co e-Shell Polyme B ushes” by Ma kus Müllne , Thomas Lunkenbein, Jose B eu, F ank Ca uso, and Axel H. E. Mülle * I conduc ed all expe imen s and w o e he manusc ip , excep ha : • T. Lunkenbein pe o med SEM and EDX measu emen s; and • J. B eu and F. Ca uso we e in ol ed in co ec ing he manusc ip . • A. H. E. Mülle was in ol ed in scien i ic discussions and co ec ing he manusc ip Chap e 6 This will has been published in Small unde he i le: “A Facile Polyme Templa ing Rou e Towa d High Aspec Ra io C ys alline Ti ania Nanos uc u es” by Ma kus Müllne , Thomas Lunkenbein, Nobuyoshi Miyajima, Jose B eu,* and Axel H. E. Mülle * This is a join p ojec be ween he chai s o AC I and MC II. I conduc ed all expe imen s conce ning he p epa a ion and he analysis o he polyme ic empla es. I u he assis ed in he p epa a ion and he analysis o he nanoc ys als and he hyb id ma e ials. I was in ol ed in scien i ic discussions and w o e he manusc ip . T. Lunkenbein pe o med mos o mic oscopy expe imen s and he cha ac e iza ion o he hyb id ma e ials. He u he de eloped he syn hesis o he nanoc ys als and assis ed in he cha ac e iza ion o he sul ona ed empla es. He was in ol ed in discussions and co ec ing he manusc ip . Fu he : • N. Miyajima pe o med one o he HR-TEM measu emen s; and • J. B eu and A. H. E. Mülle we e in ol ed in scien i ic discussions and co ec ing he manusc ip . Chap e 3 – O gano-Silica Hyb id Nano ubes 70 The wo mlike shape o CPBs has been employed o ab ica e ino ganic one-dimensional (1D) nanos uc u es,28 such as γ-Fe2O3,29 CdS,30 CdSe,31 Au,32 and i ania33 nanowi es. Commonly, in a solu ion app oach, he ino ganic p ecu so s ha e been i s localized in he cylind ical co e a ea by selec i ely in e ac ing wi h he CPB co e block. Th ough chemical eac ions occu ing only wi hin he co e, he p ecu so s ha e been con e ed in o co esponding unc ional ino ganic nanoma e ials, which we e spa ially o ganized by he cylind ical empla e o adop a wi e-like geome y. The CPB shell, ee o in e ac ion wi h he ino ganic moie ies, p o ec s he o med ino ganic nanowi es om agglome a ion and solubilizes hem in sol en s. Solubili y in wa e o o ganic sol en s and biocompa ibili y o he hyb id nanowi es can be achie ed by he design o he shell block.33,34 F ees anding, pu ely ino ganic nanowi es can be achie ed by py oly ic emo al o he polyme ic empla e on a solid subs a e. In gene al, he dimensions o he desi ed 1D ino ganic nanos uc u e a e s ic ly con olled by he CPBs. Fo example, he diame e depends on he leng h o he block in he CPB co e, and he leng h is la gely de e mined by he deg ee o polyme iza ion o he backbone.34 We ecen ly epo ed a no el s a egy o o m hyb id cylinde s wi h an o gano-silica co e, whe e he p ecu so o he ino ganic pa is a building uni o he co e i sel .34 O gano-silica hyb id nanowi es we e p oduced by using poly[(3-ac yloxyp opyl) ime hoxysilane] (PAPTS) as he co e and poly[oligo(e hylene glycol) me hac yla e] (POEGMA) as he co ona, ollowed by hyd oly ic condensa ion o he PAPTS co e block o o m a c osslinked silsesquioxane s uc u e, which could be py olized o o m pu e silica nanowi es.35 Cylind ical o ubula hyb id ma e ials ha a e no de i ed om CPBs ha e been syn hesized by using block copolyme s as di ec ing agen s.18,36 So a , only co e-shell s uc u ed CPBs wi h diblock copolyme side chains ha e been chosen as syn he ic 1D empla es. He ein, we demons a e he i s ime ha co e-shell- co ona s uc u ed CPBs wi h iblock e polyme side chains a e employed as an in-si u empla e o he cons uc ion o o gano-silica hyb id nano ubes, which a e soluble in a ious sol en s. Fi s ly, block e polyme side-chains o poly( e -bu yl ac yla e)-block- PAPTS-block-POEGMA we e g own om a poly(2-(2-b omoisobu y yloxy)e hyl me hac yla e) (PBIEM) polyini ia o backbone ia ATRP. They we e hen used as a unimolecula cylind ical empla e o he in-si u ab ica ion o wa e -soluble o gano-silica hyb id nano ubes ia condensa ion o he PAPTS shell block. The o med ubula Chap e 3 – O gano-Silica Hyb id Nano ubes 71 s uc u es we e cha ac e ized by ansmission elec on mic oscopy (TEM), c yogenic TEM (c yo-TEM) and a omic o ce mic osopy (AFM). So ubula nanos uc u es ha e also been p epa ed om small su ac an s37,38 amphiphilic block copolyme s39-43 o mul icomponen copolyme cylind ical b ushes.44,45 Howe e , mos o hese con en ional ubula s uc u es a e only dynamically s able and can collapse upon a iny pe u ba ion in he ex e nal en i onmen such as a sol en , empe a u e, concen a ion, o pH change. In addi ion, he size and size dis ibu ion o assembled s uc u es a e usually ha d o con ol. In con as , due o he li ing / con olled polyme iza ion echniques employed in he p epa a ion o CPBs, he ob ained hyb id ubula s uc u es a e uni o m in diame e and leng h. They a e s able and ole an o a ia ions in hei en i onmen because he shape and s uc u e o each nano ube is co alen ly locked. Expe imen al Sec ion Ma e ials. All chemicals we e o analy ical g ade and used as ecei ed wi hou u he pu i ica ion, excep ha (3-ac yloxyp opyl) ime hoxysilane (APTS) (95%, ABCR) was eshly dis illed, and e -bu yl ac yla e ( BA) (98%, Ald ich) and oligo(e hylene glycol) me hac yla e (OEGMA) (98%, Ald ich) we e il e ed h ough a basic alumina column sho ly be o e each polyme iza ion. P epa a ion o co e-shell-co ona CPB [ BA75-APTS115-OEGMA150]3200. The poly(mac oini ia o ) backbone poly(2-(2-b omoisobu y yloxy)e hyl me hac yla e) (PBIEM) was p epa ed by anionic polyme iza ion o 2-( ime hysilyloxy)e hyl me hac yla e, acidic clea age o he ime hylsilyl g oups, and an es e i ica ion eac ion o a ach he ATRP ini ia ing si es on o each epea ing uni as de ailed ea lie .13 The deg ee o polyme iza ion (DP) o he PBIEM polyini ia o backbone is 3200, and i s polydispe si y index, de e mined by gel pe mea ion ch oma og aphy (GPC), is 1.14. The syn hesis o a P BA homopolyme CPB in anisole was de ailed in ou p e ious pape .13 The ini ia ing e iciency o he PBIEM poly(mac oini ia io ) backbone owa ds BA was de e mined as 0.65 by clea ing he P BA side chains and de e mining hei molecula weigh by GPC. The ATRP o APTS o he shell block and OEGMA o he co ona block was conduc ed exclusi ely in benzene in o de o supp ess he hyd olysis and condensa ion o he ime hoxysilyl g oups in he PAPTS shell block.34 Typically, in a lask equipped wi h a Chap e 3 – O gano-Silica Hyb id Nano ubes 72 sep um, CuB , he poly(mac oini ia o ), and he monome (APTS o OEGMA) we e added in benzene. The mix u e was degassed and s i ed un il comple e dissolu ion o he poly(mac oini ia o ) and hen hea ed o 110 °C (in he case o APTS) o 80 °C (in he case o OEGMA). Finally, he degassed ligand, N,N,N',N",N''-pen ame hyldie hylene iamine (PMDETA), was injec ed o s a he polyme iza ion and an ini ial sample was aken o 1H-NMR measu emen . The polyme iza ion was moni o ed by wi hd awing samples o 1H-NMR measu emen s. When a desi ed con e sion was achie ed, he eac ion was quenched by cooling he eac ion mix u e o oom empe a u e and exposing i o ai . The eac ion mix u e was pu i ied by il a ion h ough a basic alumina column, and by ul a il a ion using benzene as he eluen unde ni ogen a mosphe e. P epa a ion o [( BA)75-b-(SiO1.5)115-b-(OEGMA)150]3200 hyb id o gano-silica nano ubes. 400 mg o [ BA75-APTS115-OEGMA150]3200 co e-shell-co ona CPBs in 200 ml 1,4-dioxane was mixed wi h 20 ml o a 25% aqueous solu ion o ammonia. The eac ion mix u e was kep unde cons an s i ing a oom empe a u e o 5 days o comple e he condensa ion o he ime hoxysilyl g oups. The ammonia was la gely emo ed by o a ional e apo a ion a 30° C and he esul ing solu ion was pu i ied by dialysis agains dioxane. Cha ac e iza ion Me hods. Gel Pe mea ion Ch oma og aphy (GPC) in THF was conduc ed a an elu ion a e o 1 mL/min using PSS SDVgel columns (300 X 8mm, 5 µm): 105, 104, 103, and 102 Å and RI and UV (λ =254 nm) de ec ion. Poly( e -bu yl ac yla e) calib a ion cu e was used o calib a e he columns, and oluene was used as an in e nal s anda d. A omic o ce mic oscopy (AFM) images we e eco ded on a Digi al Ins umen s Dimension 3100 mic oscope ope a ed in apping mode. The samples we e p epa ed by dip-coa ing om dilu e solu ions (0.02 g/L) o he polyme b ush o hyb id nano ubes solu ion in dioxane o benzene on o a clean silicon wa e o eshly clea ed mica o o m a monomolecula ilm. T ansmission elec on mic oscopy (TEM) images we e aken on a Zeiss EM EF-TEM ins umen ope a ed a 200 kV. A 5µL d ople o a dilu e solu ion (0.05 g/L) in dioxane o benzene was d opped on o a coppe g id (200 mesh) coa ed wi h ca bon ilm, ollowed by blo ing he liquid and d ying a oom empe a u e o a sho ime. Chap e 3 – O gano-Silica Hyb id Nano ubes 73 C yogenic ansmission elec on mic oscopy (c yo-TEM) was conduc ed by d opping he aqueous dilu e solu ion (0.1 g/L) on a hyd ophilized lacey TEM g id, whe e mos o he liquid was emo ed wi h blo ing pape , lea ing a hin ilm s e ched o e he g id holes. The specimens we e shock ozen by apid imme sion in o liquid e hane and cooled o app oxima ely 90 K by liquid ni ogen in a empe a u e-con olled eezing uni (Zeiss C yobox, Zeiss NTS GmbH, Obe kochen, Ge many). A e he specimens we e ozen, he emaining e hane was emo ed using blo ing pape . The specimen was inse ed in o a c yo- ans e holde (CT3500, Ga an, München, Ge many) and ans e ed o a Zeiss EM922 EF-TEM ins umen ope a ed a 200 kV. C yo-TEM samples om o ganic sol en s, such as THF, we e shock ozen in liquid ni ogen, espec i ely. P o on nuclea magne ic esonance (1H-NMR) spec a we e eco ded o de e mine he monome con e sion on a B uke AC-300 spec ome e a oom empe a u e in CDCl3. Resul s and Discussion ATRP was employed o g a P BA-b-PAPTS-b-POEGMA block e polyme side chains om a PBIEM polyini ia o backbone, along which 3200 ATRP ini ia ing si es we e e he ed on o each epea ing uni .13 As shown in he gene al syn he ic ou e in Scheme 3- 1, h ee monome s - namely e -bu yl ac yla e ( BA), (3-ac yloxyp opyl) ime hoxysilane (APTS) and oligo(e hylene glycol) me hac yla e (OEGMA) - we e sequen ially polyme ized in anisole o benzene using CuB / PMDETA as he ca aly ic sys em. Finally, he PAPTS shell block o he ob ained co e-shell-co ona s uc u ed CPBs was condensed in o a silsesquioxane ne wo k in he shell. Chap e 3 – O gano-Silica Hyb id Nano ubes 74 Scheme 3-1. Syn he ic ou e o ob ain wa e -soluble o gano-silica hyb id nano ubes empla ed by co e- shell-co ona s uc u ed CPBs. (A) ATRP polyini ia o backbone (PBIEM) wi h DP ~ 3200; (B) co e-shell- co ona s uc u ed CPB [ BA75-b-APTSx-b-OEGMAy]3200; and (C) wa e -soluble o gano-silica hyb id nano ubes [ BA75-b-(SiO1.5)x-b-OEGMAy]3200. To con i m he success ul in oduc ion o each block in o he side chains, 1H-NMR spec a we e eco ded a each block g ow h s ep. When BA was polyme ized om he PBIEM polyini ia o backbone, he 1H-NMR peaks o PBIEM in Figu e 3-1A comple ely anished due o hei a he low con en (< 3%). Ins ead, he homopolyme CPB [ BA75]3200 (Figu e 3-1B) showed a cha ac e is ic sha p peak a 1.44 ppm, assigned o he p o ons in he e -bu yl g oups. The P BA homopolyme CPBs we e hen used as he poly(mac oini ia o ) o he g ow h o he PAPTS shell. Figu e 3-1C shows he 1H-NMR spec um o he diblock copolyme CPBs [ BA75-b-APTS50]3200. Besides he peak a 1.44 ppm, ano he in ensi e peak appea s a ~3.5 ppm, indica ing he appea ance o ime hoxysilyl g oups co esponding o he success ul g ow h o he PAPTS block. In he same manne , he block copolyme CPBs [ BA75-b-APTS50]3200 was used as poly(mac oini ia o ) o he ATRP o OEGMA. The in ensi y o he peak a 3.5 ppm (Figu e 3-1D/E) is enhanced due o he o e lapping o he e hylene p o on signals o he oligo(e hylene glycol) moie ies and hose o he ime hoxysilyl g oups. Chap e 3 – O gano-Silica Hyb id Nano ubes 75 Figu e 3-1. 1H-NMR spec a o : (A) PBIEM polyini ia o backbone, (B) [ BA75]3200 CPB, (C) [ BA75-b- APTS50]3200 CPB, (D) [ BA75-b-APTS50-b-OEGMA30]3200 CPB, and (E) [ BA75-b-APTS50-b-OEGMA300]3200 CPB. All samples we e measu ed in CDCl3. We ound he leng h o he POEGMA block o be e y c ucial o he success o he syn he ic s a egy. A sho POEGMA co ona (DP = 30, 1H-NMR in Figu e 3-1D) esul ed in an insu icien sc eening, leading o in e molecula coupling and esul ing in la ge agglome a es ha a e uns able in solu ion. The e o e, a ious e polyme b ushes wi h a a he long POEGMA co ona we e syn hesized ia he “g a ing om” app oach. A e he dialysis o [ BA75-b-APTSx-b-OEGMAy]3200 om benzene o dioxane, he condensa ion o he PAPTS shell was ca ied ou by aqueous ammonia. The ime hoxysilyl g oups we e condensed in o a c osslinked silsesquioxane shell. The c osslinked p oduc s, [ BA75-b-(SiO1.5)x-b-OEGMAy]3200 o gano-silica hyb id nano ubes, a e s able in a ious sol en s, like non-pola benzene and oluene, as well as pola me hanol and wa e . Table 3-1 summa izes he syn hesized o gano-silica hyb id nano ubes and hei dimensions in aqueous solu ion. Chap e 3 – O gano-Silica Hyb id Nano ubes 76 Table 3-1. O gano-silica hyb id nano ubes wi h di e en dimensionsa (in nm) Nano ube composi ionb Leng hc Tube diame e c Shell hicknessc,d BA75-b-(SiO1.5)50-b-OEGMA300 460 ± 120 18 ± 2 ~4 BA 75 -b-(SiO 1.5 ) 115 -b-OEGMA 150 330 ± 70 27 ± 3 ~10 BA 75 -b-(SiO 1.5 ) 170 -b-OEGMA 400 285 ± 55 33 ± 3 ~14 a Polyme hac yla e backbone wi h 3200 epea ing uni s. b Nano ube composi ion a e c osslinking. c Leng h as e alua ed om c yo-TEM measu emen s, d aking in o accoun ha he P BA co e is always a ound 8 ± 1 nm. Molecula isualiza ion ia a omic o ce mic oscopy (AFM) on mica o silicon wa e has been p o en o be a powe ul cha ac e iza ion me hod o e i y he success ul syn hesis and he mo phological changes o CPBs.10,34 Figu es 3-2A-I a e he AFM images o in e media e and inal p oduc CPBs a each syn he ic s ep. Figu e 3-2A shows a densely packed monolaye o [ BA75]3200 CPBs wi h uni o m diame e and na ow leng h dis ibu ion. A s a is ical measu emen de e mines ha hei a e age leng h is 285 ± 74 nm. The c oss-sec ion analysis o a single la ened P BA CPB (Figu e 3-2B) shows a heigh in i s cen e o 1.7 nm (Figu e 3-2C). I is epo ed ha he epulsion among he dense side chains inc eases wi h he side chains leng h and monome bulkiness.1,46,47 He e, by ex ending he side chains by g a ing PAPTS as he shell block, he epulsion be ween he side chains inc eases as expec ed. Figu es 3-2D and 3-2E show he AFM images o he diblock copolyme CPBs [ BA75-b-APTS115]3200. The a e age leng h is measu ed o be 375 ± 50 nm, 30% longe han ha o he [ BA75]3200 CPBs. The c oss- sec ion analysis o he indi idual CPBs (Figu e 3-2F) e eals an inc ease in he heigh up o 4.5 nm, ca. 200 % highe han ha o [ BA75]3200. In he absence o a co ona block, du ing he condensa ion s ep, he diblock copolyme [ BA75-b-APTS115]3200 CPBs unde go bo h in amolecula and in e molecula c osslinking, which p ecipi a es he CPBs ou o solu ion. Thus a co ona block is equi ed o sc een he in e molecula coupling be o e he condensa ion s ep and ac s as a p o ec i e laye . The e o e, a POEGMA block wi h a DP o 150 was g a ed (Figu e 3-2G-I) o ob ain he inal [ BA75-b-APTS115-b- OEGMA150]3200 CPB. The a e age leng h sligh ly inc eased o 400 ± 50 nm. The c oss- sec ion analysis e ealed a u he inc ease in heigh o 8.2 nm. The wid hs (Figu e 3-2 C/F/I) also inc eased wi h each polyme iza ion s ep. Howe e , he wo m-like s uc u es appea b oade in AFM han in TEM o c yo-TEM measu emen s due o hei sp eading Chap e 3 – O gano-Silica Hyb id Nano ubes 77 on he silicon wa e su ace. I is possible o isualize he POEGMA co ona wi h AFM (Figu e 3-2G/H), howe e he alues o he wid h o abo e 150 nm can only de i e om he wo ms being sp ead ou on o he silicon wa e su ace. Figu e 3-2. Tapping-mode AFM heigh images (o e iew and close iew) and he co esponding heigh c oss-sec ion analysis o [ BA75]3200 (A-C), [ BA75-b-APTS115]3200 (D-F), [ BA75-b-APTS115-b- OEGMA150]3200 (G-I), and [ BA75-b-(SiO1,5)115-b-OEGMA150]3200 (J-L). Z- anges a e 5 (A), 8 (B), 9 (D), 10 (E), 15 (G), 20 (H/J), and 25 nm (K), espec i ely. The scale-ba s co espond o 500 nm (A/D/G/J) and 100 nm (B/E/H/K), espec i ely. Chap e 3 – O gano-Silica Hyb id Nano ubes 78 As men ioned, he c osslinked p oduc , [( BA)75-b-(SiO1.5)115-b-(OEGMA)150]3200 o gano- silica hyb id nano ubes, a e s able in a ious sol en s and wa e . AFM images o he hyb id o gano-silica nano ubes a e shown in Figu e 3-2J/K. The cylind ical mo phology was main ained du ing he comple e syn he ic ou e, and ac ually shaped he silsesquioxane ne wo k in o a ubula s uc u e. In e es ingly, he a e age leng h o he c osslinked [ BA75-b-(SiO1,5)115-b-OEGMA150]3200 sh inks om 400 ± 50 o 300 ± 60 nm; meanwhile, hei heigh inc eases u he o 13.2 nm (Figu e 3-2L), ~60% highe han he p ecu so s (8.2 nm). The longi udinal size con ac ion and ho izon al size expansion esul om he in amolecula c osslinking o he side chains. Since mo e chemical bonds a e gene a ed among he side chains in he condensa ion p ocess, he epulsion o ce among he side chains is la gely compensa ed. A he same ime, bo h he P BA co e and he hyb id silica shell we e chemically locked in he CPB cen e and could no sp ead o e he su ace, which enhances he heigh in he CPB cen e . T ea men wi h hyd ogen luo ide in THF opens he silsesquioxane ne wo k again. Due o he missing c osslinks, he backbone is hen able o s e ch again. In he case o [ BA75-b-(SiO1.5)170-b- OEGMA400]3200, he a e age leng h o he backbone inc eased om 285 nm o abo e 400 nm (see Suppo ing In o ma ion 3-S3). As AFM measu emen s only depic he su ace mo phology, he in insic s uc u e o hese hyb id nano ubes was e ealed by TEM and c yo-TEM measu emen s. Wi h TEM cha ac e iza ion, nano ubes appea ligh e in he cen e han a he wall, simila o ca bon nano ubes. Howe e , o he hyb id o gano-silica nano ubes syn hesized he e, he co e is no emp y, bu illed pa ially wi h P BA polyme . Since he polyme has a weak con as compa ed o ino ganic o hyb id ma e ials, a ubula s uc u e is hus s ill expec ed. In he d y s a e, he hyb id nano ubes in no mal TEM measu emen s show wo m-like mo phology (Figu e 3-3), indica ing ha he cylind ical empla es wo k e icien ly o he p esen syn he ic s a egy. The nano ubes enla ged in Figu e 3-3B/C/E appea ligh e in he co e, as expec ed. The diame e s o he co e and o he shell o [ BA75-b-APTS115-b- OEGMA150]3200 in he d y s a e a e 13-17 nm and 33-37 nm. Tha gi es a wall hickness o ~10 nm. Fo he [ BA75-b-APTS170-b-OEGMA400]3200 nano ubes, he diame e o he co e s ays a ound 14-17 nm, whe e as he o al diame e (co e and shell) inc eases o a ound 45-54 nm. This esul s in a shell hickness o app oxima ely 15.5 o 18.5 nm (in d y s a e). Chap e 3 – O gano-Silica Hyb id Nano ubes 79 Figu e 3-3. TEM cha ac e iza ion o o gano-silica nano ubes in THF: non-s ained TEM images o [ BA75- b-APTS115-b-OEGMA150]3200 (A/B/C), and [ BA75-b-APTS170-b-OEGMA)400]3200 (D/E); (B/C/E) a e close- ups o non-s ained hyb id nano ubes. The scale-ba s a e 100 nm (B/C/E) and 200 nm (A/D), espec i ely. Figu e 3-4. C yo-TEM images o (A) non-c osslinked nano ubes [ BA75-b-APTS170-b-OEGMA400]3200 in THF; (B) non-c osslinked nano ubes [ BA75-b-APTS115-b-OEGMA150]3200 in wa e ; (C) hyb id nano ube [ BA75-b-(SiO1.5)50-b-OEGMA300]3200 in wa e ; (D) hyb id nano ubes [ BA75-b-(SiO1.5)115-b-OEGMA150]3200 in wa e ; (E) hyb id nano ubes [ BA75-b-(SiO1.5)170-b-OEGMA400]3200 in wa e ; and (F) a single hyb id nano ube in aqueous solu ion ( he inse is a g ay scale analysis o he a ea shown in image F). The scale- ba s ep esen 200 nm (A-E) and 20 nm (F), espec i ely. As shown abo e, TEM in es iga ions clea ly con i med he ubula s uc u es. Howe e , he weak con as o he non-c osslinked o gano-silica nano ubes in c yo-TEM measu emen s in THF made i di icul bu possible o depic he ubula s uc u es Chap e 3 – O gano-Silica Hyb id Nano ubes 86 500 nm 1µm AB Figu e 3-S3. TEM images o HF ea ed [ BA75-b-(SiO1.5)170-b-OEGMA400]3200 Chap e 4 – Ana ase Hyb id Nano ubes 87 Chap e 4 Templa e-Di ec ed Mild Syn hesis o Ana ase Hyb id Nano ubes wi hin Cylind ical Co e-Shell-Co ona Polyme B ushes The esul s o his chap e will be submi ed as: “Templa e-Di ec ed Mild Syn hesis o Ana ase Hyb id Nano ubes wi hin Cylind ical Co e-Shell-Co ona Polyme B ushes” by Ma kus Müllne , Thomas Lunkenbein, Ma in Schiede , Nobuyoshi Miyajima, Melanie Fö sch, Jose B eu, F ank Ca uso,* and Axel H. E. Mülle * Chap e 4 – Ana ase Hyb id Nano ubes 88 Chap e 4 – Ana ase Hyb id Nano ubes 89 Abs ac : We demons a e he syn hesis o uni o m one-dimensional (1D) i ania nanos uc u es using co e-shell-co ona cylind ical polyme b ushes (CPBs) as so empla es. The CPBs consis o a polyme hac yla e backbone wi h densely g a ed poly(ε- cap olac one) (PCL) in he co e, poly(2-(dime hlamino)e hyl me hac yla e) (PDMAEMA) in he ca ionic shell and poly(oligo(e hylene glycol) me hyl e he me hac yla e) (POEGMA) as he co ona. The weak polyelec oly e shell complexed an opposi ely cha ged i ania p ecu so , namely i anium(IV) bis(ammonium lac a e) dihyd oxide (TALH), and hen ac ed as a nano eac o o he hyd olysis and condensa ion o TALH, esul ing in TiO2. The POEGMA shell p o ides solubili y in aqueous and o ganic sol en s. The hyb id i ania nano ubes con aining c ys alline ana ase nanopa icles we e cha ac e ized by a omic o ce mic oscopy (AFM), ansmission elec on mic oscopy (TEM) and scanning elec ion mic oscopy (SEM). The phase pu i y o he c ys alline nanos uc u es was e i ied by powde X- ay di ac ome y (PXRD). Chap e 4 – Ana ase Hyb id Nano ubes 90 Chap e 4 – Ana ase Hyb id Nano ubes 91 In oduc ion One-dimensional (1D) nanos uc u es ha e been in ensi ely s udied in ecen yea s.1-4 The abili y o p ecisely p oduce nanome e -sized ma e ials opens new possibili ies in mode n science and echnology. Thei unique size- and shape-dependen p ope ies and hei con inually expanding applica ion in a ious esea ch a eas ha e d ama ically inc eased he in e es in aniso opic nanos uc u es, such as ods, wi es and ubes.5-8 Many di icul ies associa ed wi h he syn hesis o 1D nanos uc u es ha e been o e come, and i is now possible o p ecisely ine- une he dimensions o hese nanos uc u es, as well as con ol hei mo phology, phase pu i y and chemical composi ion.9 To da e, se e al s a egies ha e been de eloped o ab ica e o ganic, hyb id and ino ganic 1D nanos uc u es.4 They can be syn hesized om ei he apo , liquid o solid phases by using mul iple me hods, and using wo undamen al s eps: nuclea ion and g ow h.5, 10-16 Xia e al. highligh ed se e al s a egies o “bo om-up” me hods as key ac o s o he ab ica ion o homogenous 1D ino ganic nanos uc u es.2 The use o capping agen s (such as su ac an s)17-19 o he sel -assembly o 0D nanos uc u es20, 21 a e examples o he p omising pa hways owa d aniso opic nanoma e ials. Ano he elegan ou e owa d 1D nanos uc u es is he di ec use o 1D empla es, including o ganic sys ems. Cylind ical polyme b ushes (CPBs),4, 22 ca bon nano ubes,23, 24 sel -assembled block copolyme s25-27 and biological supe s uc u es28-30 ( i uses o DNA) a e examples o empla es wi h p e- exis ing asymme ic shapes. The main challenges in using empla e-di ec ed app oaches a ise wi h he syn hesis and design o he cylind ical empla e a he han he ab ica ion o he hyb id ma e ial. A p omising and uni o m 1D empla e is unimolecula CPBs. These a e molecula b ushes ca ying linea side chains densely g a ed om a backbone. They can be syn hesized by using “g a ing- om”, “g a ing-on o” and “g a ing- h ough” s a egies.31 The dense packing o side chains along he polyme backbone causes s e ching o he backbone and s i ening o he en i e polyme b ush. Co e-shell- co ona s uc u ed CPBs – i.e., polyme b ushes ca ying ABC iblock e polyme s as side chains – ha e p o en o be in e es ing building blocks and empla es. Rzaye and cowo ke s ecen ly showed molecula anspo h ough polyme ic nano ubes p epa ed om co e-shell-co ona CPBs.32 Th ough he incompa ibili y o each side chain block, he polyme b ush can be di ided in o di e en 1D in e io domains, wi h leng hs up o se e al hund ed nanome e s. Such Chap e 4 – Ana ase Hyb id Nano ubes 92 s uc u es ac as ideal 1D nano eac o s o he syn hesis o aniso opic hyb id and ino ganic nanos uc u es. The e a e a numbe o s udies on using unimolecula so empla es such as CPBs o he ab ica ion o well-de ined aniso opic nanoma e ials. Co e-shell CPBs ha e been used o he ab ica ion o TiO2,33 CdS,34 CdSe35 and SiO236 hyb id nanowi es, as well as co e-shell-co ona CPBs o he ab ica ion o silica hyb id nano ubes.37 All o hese nanoma e ials ha e only one compa men o he empla e, o example he shell o he co e, ha hos s gues molecules, such as sal s o ino ganic p ecu so s. These gues molecules can be ei he loaded in o he compa men o al eady co alen ly bonded inside he compa men . The loading o ino ganic ma e ial can be pe o med ia wo ways, he in si u gene a ion o ino ganic ma e ial wi hin he empla e35, 38 o he loading o p esyn hesized nanoscopic ma e ials in o a empla e compa men .25, 38 Such nanos uc u ing o ino ganic ma e ials has a ac ed conside able in e es , as he esul ing ma e ials o en exhibi high su ace a eas and small sizes o he ino ganic nanopa icles, which p o ide hem wi h unique op ical, elec ical and ca aly ic p ope ies.39-42 Nanoma e ials o i ania (TiO2) a e o pa icula in e es , as i is possible o con ol hei physical and chemical cha ac e is ics h ough syn hesis pa hways. Consequen ly, he e exis s a la ge a ie y o applica ions o TiO2 nanoma e ials in he ields o gas sensing, dielec ic ce amics, ca alys s, pho o ol aic sola cells and pigmen s.42-47 In ou p e ious wo k, we syn hesized TiO2 nanowi es om a bis-hyd ophilic co e-shell polyme b ush [HEMA85-OEGMA200]3200 and i anium e a(n-bu oxide), Ti(OBu)4.33 In ha s udy, Ti(OBu)4 was immobilized in o he poly(2-hyd oxye hyl me hac yla e) (PHEMA) compa men h ough ansalcoholysis and a subsequen hyd olysis s ep led o uni o m TiO2 nanowi es. Howe e , alkoxy-based i ania p ecu so s a e e y labile o hyd olysis, especially in aqueous solu ion. Mos ly hey only o m amo phous TiO2 and a e hen con e ed in o c ys alline TiO2 h ough addi ional s eps like hea ea men .33, 48, 49 Al hough he loading was pe o med in dioxane, i ne e heless had he side e ec ha i ania nanopa icles we e no only complexed in he PHEMA co e bu also in he shielding POEGMA co ona. He ein, we in il a ed a nega i ely cha ged ino ganic i ania p ecu so o coo dina e exclusi ely in o one o he empla e b ush compa men s. We used a co e-shell-co ona CPB, consis ing o a PHEMA backbone wi h poly(ε-cap olac one) (PCL) as he co e, poly[2-(dime hylamino)e hyl me hac yla e] (PDMAEMA) as he polyca ionic shell, and Chap e 4 – Ana ase Hyb id Nano ubes 93 poly(oligo(e hylene gylcol) me hyl e he me hac yla e) (POEGMA) as he solublizing co ona, as a empla e o he ab ica ion o ana ase nano ubes. The applied polyme iza ion echniques ga e excellen con ol o e he syn hesis o he empla e b ushes and hence allowed p ecise adjus men o he diame e o he TiO2 nano ubes. Using ing-opening polyme iza ion o ε-cap olac one (CL) led o a high g a ing e iciency o side chains because he PCL chains ha e low s e ic equi emen s. In addi ion, hey can be deg aded by es e hyd olysis. A om ans e adical polyme iza ion (ATRP) allowed he homogenous and sequen ial ailo ing o he shell and he co ona. The use o a cha ged TiO2 p ecu so , i anium(IV) bis(ammonium lac a e) dihyd oxide (TALH), had wo key ad an ages compa ed o ou p e ious wo k. Fi s , TALH gua an eed s abili y in espec o spon aneous hyd olysis du ing he loading o he empla e a ambien empe a u es. TALH has al eady been used o p oduce i ania coa ings on silica gels,50 laye ed gold nanopa icles51 and polyme ic subs a es,52 and i s con olled hyd olysis and condensa ion a ele a ed empe a u es and di e en pH alues is well s udied and documen ed. Second, he p ecise and exclusi e coo dina ion o TALH in o he PDMAEMA shell compa men allowed he ab ica ion o homogenous TiO2 nanoma e ials. No undesi ed TiO2 was ound in he co ona o in solu ion. Chap e 4 – Ana ase Hyb id Nano ubes 94 Scheme 4-1. Schema ic illus a ion o he empla e p epa ed om PHEMA by he combina ion o ROP and ATRP o o m (i) co e-shell-co ona CPBs (ii). Complexa ion o he i anium sal TALH in o he CPBs (iii) and i s hyd olysis and condensa ion o o m soluble ana ase nano ubes (i ). Expe imen al Sec ion Ma e ials All chemicals we e o analy ical g ade and used as ecei ed wi hou u he pu i ica ion, excep o 2-(dime hylamino)e hyl me hac yla e (Ald ich, 98%) and oligo(e hylene glycol) me hyl e he me hac yla e (Ald ich, 98%, Mn ~ 300 g·mol-1), which we e passed h ough a silica column p io o polyme iza ion. P epa a ion o he polyme b ush [PCL-b-PDMAEMA-b-POEGMA]x. The empla e was syn hesized h ough he combina ion o anionic, ing opening and ATRP. The s epwise buildup om a polyini ia o backbone o a co e-shell cylind ical polyme b ush [CL14-DMAEMA40-OEGMA65]7500 is explained in de ail below. Chap e 4 – Ana ase Hyb id Nano ubes 95 Syn hesis o HEMA7500 backbone. The polyini ia o backbone PHEMA was ob ained h ough dep o ec ion o poly(2-( ime hylsiloxy)e hyl me hac yla e) (PTMS-HEMA). The PTMS-HEMA backbone was syn hesized as p e iously epo ed by Mo i e al.53 The molecula weigh was de e mined by s a ic ligh sca e ing (SLS). The numbe -a e age deg ee o polyme iza ion (DPn) and he polydispe si y index (PDI) a e 7500 and 1.14, espec i ely. The dep o ec ion was pe o med wi h ace ic acid in me hanol. Syn hesis o he cylind ical polyme b ush [CL14]7500. PHEMA (80 mg, 0.62 mmol) was dissol ed in CL (6 mL, 54.2 mmol) and wa e aces we e dis illed o in he p esence o benzene. A e wa d, he mix u e was degassed by bubbling a gon o 30 min. The ing- opening polyme iza ion (ROP) o CL was ca alyzed by he addi ion o in(II) 2- e hylhexanoa e (1.5 mg, 3.70 µmol) a 125 °C. The polyme iza ion was allowed o p oceed o 11 h, un il he mix u e became e y iscous. The polyme iza ion was quenched by cooling and exposing o ai and hen dilu ed wi h THF and p ecipi a ed in o cold cyclohexane. The con e sion was de e mined a e pu i ica ion by 1H-NMR by compa ing he polyme ic CH2-signal a 4.1 ppm and he e minal CH2-signal a 3.65 ppm. The PCL homopolyme b ush [CL14]7500 was p ecipi a ed wice in o a cold wa e /me hanol mix u e (10/90 / ) and hen eeze-d ied om dioxane. [CL14]7500 was hen eac ed wi h a 1.5- old mola excess o 2-b omoisobu y yl b omide and a 2- old mola excess o ie hylamine (TEA) in d y THF o unc ionalize he PCL b ush wi h ATRP ini ia ing g oups. The eac ion mix u e was s i ed o 24 h a oom empe a u e, and hen he unc ionalized polyme was concen a ed by sol en e apo a ion, p ecipi a ed in a cold wa e /me hanol mix u e (80/20 / ) and eeze-d ied om dioxane. Syn hesis o he cylind ical co e-shell polyme b ush [CL14-DMAEMA40]7500. [CL14]7500 (8.0 µmol) was dissol ed in 7 mL o anisole and deoxygena ed o 10 min in a sc ew-cap lask sealed wi h a sep um. Then, 0.01 mmol o CuCl was added and a gon was bubbled h ough he mix u e o 20 min. Meanwhile, 5 mmol o des abilized DMAEMA, 0.01 mmol o PMDETA and 1 mL o anisole we e degassed. The polyme iza ion was s a ed a e adding he DMAEMA/PMDETA mix u e o he eac ion lask a 50 °C. The polyme iza ion was moni o ed ia 1H-NMR and quenched a he desi ed con e sion by cooling i and exposing i o ai . The polyme solu ion was passed h ough a sho silica gel column be o e i was p ecipi a ed in o cold cyclohexane. The p ecipi a e was immedia ely dissol ed in e hanol be o e a second p ecipi a ion. The polyme was dissol ed in anisole and he excess e hanol was emo ed by educed p essu e. Chap e 4 – Ana ase Hyb id Nano ubes 102 Figu e 4-2. AFM heigh images o (A) empla e b ush 1 and (B) hyd olyzed TALH in il a ed in o hyb id nano ubes, on mica. The c oss-sec ions o he co esponding AFM heigh images can be ound unde nea h he images. The z- alues a e (A) 6 nm and (B) 40 nm. Figu e 4-3 shows TEM mic og aphs o he TALH-loaded polyme b ush 1 (A, B) and he he mally hyd olyzed and condensed analogues (C, D). In all mic og aphs, he e was no excess TALH/ i ania nanopa icles isible in he backg ound and he b ush empla es we e homogeneously loaded wi h TALH/TiO2. The diame e o he TALH loaded nano ubes was a ound 28 ± 2 nm. The diame e dec eased sligh ly o 23 ± 2 nm a e hyd olysis and condensa ion. Howe e , he shape and leng h o he nano ubes emained Chap e 4 – Ana ase Hyb id Nano ubes 103 unchanged. The PCL co e o he nano ubes appea ed ligh e as compa ed o he TALH/ i ania con aining shell, due o he much lowe con as used (see g ey-scale analysis in Figu e 4-3B and D). The PCL co e emained unchanged du ing hyd olysis and had a diame e o a ound 7 nm. The POEGMA co ona o he polyme b ush (65 and 150 monome uni s, espec i ely) s ill su ounded he nano ubes and p e en ed c osslinking be ween he indi idual nano ubes. Inciden ally, some b ushes appea o ha e me ged, e.g. in Figu e 4-3D. Howe e , hese a e d ying a i ac s. Figu e 4-3. (A, B) TEM mic og aphs o TALH loaded co e-shell-co ona polyme b ushes o empla e b ush 1 and (C, D) hei hyd olyzed c ys alline analogues. (E) C yo-TEM mic og aph o TALH-loaded empla e b ush 1 in wa e . (F) TEM mic og aph o TALH-loaded and hyd olyzed empla e b ush 2. The inse s in B, D, E and F show he g ey-scale analysis o c oss-sec ions h ough he espec i e nano ube. Chap e 4 – Ana ase Hyb id Nano ubes 104 The POEGMA co ona solubilized and s abilized he TiO2 nano ubes in bo h o ganic and aqueous solu ions. C yogenic TEM (c yo-TEM) images highligh ed he good dispe sibili y o TALH nano ubes in wa e (see Figu e 4-3E). The PCL co e was again dis inguishable due o he lowe con as (see magni ica ion and g ey-scale analysis in Figu e 4-3E). The POEGMA co ona was no isible in he TEM images. The loading in o and subsequen hyd olysis o TALH wi hin he b ush 2 led o an inc ease in hickness o abou 39 ± 2 nm due o he la ge PDMAEMA shell compa men (see Figu e 4-3F). Se e al g oups ha e s udied he hyd olysis o TALH and demons a ed ha i can c ys allize o gi e he ana ase polymo ph o TiO2.52 I is well known ha TALH apidly unde goes hyd olysis a empe a u es abo e 70 °C.52, 56 I was also shown ha he he mal hyd olysis o TALH p oceeds smoo hly upon s ep-wise hea ing.57 The e o e, we commenced hyd olysis o he TALH-loaded polyme b ushes a 60 °C and con inued s epwise hea ing owa d 80 °C wi hin 3 hou s ( aising empe a u e by 6-7 °C e e y 30 min). The nano ubes we e hen e luxed (95 °C) o e nigh in e hanol o ensu e comple e hyd olysis. Powde X- ay di ac ome y (PXRD) o he ai -d ied TiO2 nano ubes con i med he ana ase c ys al s uc u e (see Figu e 4-4B). Peak b oadening e ealed ha he c ys alline nanopa icles we e qui e small. Thus, as migh be expec ed, he hyb id b ushes do no ep esen single c ys als o µm dimension bu he ino ganic walls a e a he polyc ys alline, composed o many small, igh ly agg ega ed c ys alli es. E alua ing pa icle sizes applying he Sche e o mula ga e diame e s o 3-4 nm which is in good ag eemen wi h HR-TEM obse a ions (Figu e 4-4A). Mo eo e , as he c ys al la ices a e clea ly isible, HR-TEM e i ied ha he nano ubes, p oduced upon hyd olysis, we e highly c ys alline. Chap e 4 – Ana ase Hyb id Nano ubes 105 Figu e 4-4. (A) HR-TEM mic og aph o an ana ase nano ube om empla e b ush 1. The magni ica ion clea ly e eals c ys alline a eas wi hin he nano ube. (B) Powde XRD pa e n o hyd olyzed TALH nano ubes. The icks on he x-axis in (B) indica e he expec ed posi ions o he ana ase e lexes . Bo h empla e b ushes 1 and 2 we e designed o ha e an equal weigh con en o PDMAEMA o a ound 25 w % compa ed o he o e all Mn. This made i easie o compa e he amoun o ino ganic ma e ial ha was inco po a ed in o he PDMAEMA shell. The mog a ime ic analysis (TGA) de e mined he weigh con en o TiO2 in he empla e b ushes wi h 40 epea ing uni s o DMAEMA o be 39 w %, whe eas he empla e b ushes wi h 150 epea ing uni s o DMAEMA we e able o embed 47 w % o TiO2 (Figu e 4-5). TGA he eby e ealed ha longe PDMAEMA chains, as expec ed, we e able o load sligh ly mo e TALH in o he shell. We assume ha wi h inc easing leng h o polyme b ush side chains, he mobili y and space o hese chains inc eases as well. Consequen ly, he e is mo e oom o he inco po a ion o ma e ial, which acco dingly inc eases he loading capaci y. Chap e 4 – Ana ase Hyb id Nano ubes 106 Figu e 4-5. TGA o he ana ase hyb id nano ubes om empla e b ush 1 (black solid line) and empla e b ush 2 ( ed dashed line). Figu e 4-6. (A/B) TEM mic og aphs o calcined ana ase nano ubes. (B) The whi e a ows indica e he ubula s uc u e a e calcina ions. Chap e 4 – Ana ase Hyb id Nano ubes 107 Calcina ion o he ana ase hyb id nanoma e ial in ai esul ed in he emo ale o he empla e b ush which hus esul ed in pu e ana ase nano ubes (Figu e 4-6). Addi ionally, he c ys alline nanoma e ials we e deposi ed on silicon wa e s and in es iga ed wi h scanning elec on mic oscopy (SEM; Figu e 4-7). SEM highligh ed, again, he uni o mi y in hickness o he ana ase nano ubes. Highly concen a ed dispe sions o ana ase hyb id nano ubes o med non-wo en ne wo ks o hyb id nano ubes upon ( eeze-)d ying (Figu e 4-7A–D). Those ne wo ks we e p ese ed a e calcina ion in ai a 650 °C. Figu es 4-7E and 4-7F unde lined he high po osi y o ino ganic nanoma e ials ob ained by his me hod. TEM and SEM bo h e ealed ha he wo m-like s uc u es e ained hei shape a e calcina ion (see Suppo ing In o ma ion 4-S2). The su ace a ea o he d ied hyb id ma e ial was 16 m2·g-1, as de e mined by B unaue -Emme -Telle analysis o N2- physiso p ion iso he ms. Chap e 4 – Ana ase Hyb id Nano ubes 108 Figu e 4-7. SEM images o (A, B) as-p epa ed ana ase hyb id nano ubes om empla e b ush 1 (d ied om solu ion), (C, D) eeze-d ied ana ase hyb id nano ubes om empla e b ush 2 a di e en magni ica ions, and (E, F) eeze-d ied ana ase hyb id nano ubes om empla e b ush 2 a e calcina ion in an ai a mosphe e. Chap e 4 – Ana ase Hyb id Nano ubes 109 Conclusions Ou empla e-di ec ed app oach o hyb id o ma ion allows he syn hesis o highly c ys alline 1D TiO2 nano ubes in a mild p ocess a ela i ely low empe a u es (70 °C). The molecula co e-shell-co ona b ushes wi h a polyca ionic shell se ed as ideal 1D nano eac o s o he in il a ion o nega i ely cha ged molecula i ania p ecu so s and gua an eed a homogeneous illing in one dimension. The hyd o- and sol ophilic co ona p o ides su icien solubili y in a ious media and p e en s c osslinking du ing hyd olysis and condensa ion. Wi h his e sa ile ou e owa d highly c ys alline aniso opic TiO2 nanos uc u es, i is possible o a y he leng h and diame e o he hyb ids by adjus ing he backbone and leng h o he side chains. The excellen dispe sibili y in a ious media makes he 1D ana ase hyb ids in e es ing o p oducing TiO2 ilms o ne wo ks (Figu e 4-7D). Those ilms should be po ous (simila o Figu e 4- S2D) a e hea ea men . Fu he mo e, he non-wo en mesos uc u e o he hyb id ma e ials is e ained e en a e calcina ion. Acco dingly, highly c ys alline TiO2 nanoma e ials we e ob ained, which may se e as ca alys s, ba e y ma e ials o in pho o ol aic applica ions. Acknowledgmen s. This wo k was unded by he Collabo a i e Resea ch Cen e (SFB) 840 wi hin p ojec A7 and he Aus alian Resea ch Council unde he Disco e y P ojec Scheme. The au ho s hank Ma ie a Böhm and Lena Geiling o pe o ming SEC and N2 physiso p ion measu emen s, espec i ely. We u he hank P o . And eas Fe y (Physical Chemis y II, Uni e si ä Bay eu h) o gi ing us access o he AFM. M. Müllne hanks BayEFG o a schola ship. T. Lunkenbein acknowledges he ellowship p o ided by he in e na ional g adua e school o he ENB “S uc u es, Reac i i y and P ope ies o Me al Oxides”. Suppo ing In o ma ion A ailable. NMR o PCL b ush (4-S1) and TEM and SEM images o calcined ana ase nanos uc u es (4-S2). This ma e ial is a ailable ee o cha ge ia he In e ne a h p://pubs.acs.o g. Chap e 4 – Ana ase Hyb id Nano ubes 110 Re e ences (1) Luan, Z.; Maes, E. M.; an de Heide, P. A. W.; Zhao, D.; Cze nuszewicz, R. S.; Ke an, L. Chem. Ma e . 1999, 11, (12), 3680-3686. (2) Xia, Y.; Yang, P.; Sun, Y.; Wu, Y.; Maye s, B.; Ga es, B.; Yin, Y.; Kim, F.; Yan, H. Ad . Ma e . 2003, 15, (5), 353-389. (3) Schmid , V.; Wi emann, J. V.; Senz, S.; Gösele, U. Ad . Ma e . 2009, 21, (25-26), 2681-2702. (4) Yuan, J.; Mülle , A. H. E. Polyme 2010, 51, (18), 4015-4036. (5) Cadema i i, L.; Ozin, G. A. Ad . 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S.; Lee, H.-i.; Jakubowski, W.; Nese, A.; Ma yjaszewski, K.; Anokhin, D.; I ano , D. A. Mac omolecules 2009, 42, (22), 9008-9017. (55) Sheiko, S. S.; Sun, F. C.; Randall, A.; Shi anyan s, D.; Rubins ein, M.; Lee, H.-i.; Ma yjaszewski, K. Na u e 2006, 440, (7081), 191-194. (56) Möckel, H.; Gie sig, M.; Willig, F. J. Ma e . Chem. 1999, 9, (12), 3051-3056. (57) Mayya, K. S.; Gi ins, D. I.; Dibaj, A. M.; Ca uso, F. Nano Le . 2001, 1, (12), 727-730. Chap e 5 – Silica Nanowi es and Nano ubes 118 Chap e 5 – Silica Nanowi es and Nano ubes 119 In oduc ion The use o hollow ino ganic nanos uc u es as po en ial nanoscale eac o s has been s udied ex ensi ely.1-9 In e io ca i ies can hos eac an s o ca alys s and shield hem om he ou e en i onmen . The mos s udied hollow nanos uc u es a e hollow sphe es. Howe e , one-dimensional (1D) ino ganic nanos uc u es, such as ubes, ods and wi es, ha e gained conside able in e es due o hei high aspec a io and hei po en ial applica ion in elec onic, op ical and mechanical de ices.10-12 The unique size- and shape- dependen p ope ies o 1D nanoma e ials and hei con inually expanding applica ions in a ious esea ch a eas ha e d ama ically inc eased he in e es in aniso opic nanos uc u es.13-15 1D ino ganic nanos uc u es o en ind use as senso s o in ca alysis.12,16,17 In ea ly esea ch, he explo a ion o 1D nanoma e ials was hampe ed as he syn hesis and con ol o a dis inc geome y a ex emely small sizes we e di icul .18 Many 1D nanos uc u es a e buil up ia empla ing p ocesses whe e a sui able empla e p ede e mines he shape and size o he hyb id ma e ial. I is gene ally accep ed ha empla e-di ec ed syn heses p o ide a simple, high- h ough-pu , and cos -e ec i e p ocedu e which allows he s aigh o wa d p oduc ion o hyb id ma e ial, o en in only one s ep.12 In gene al, he applied empla es a e e e ed o as ei he ha d o so . Whe eas ha d empla es a e mos ly om anodized aluminuim oxide (AAO), so empla es can a y om simple su ac an micelles o mo e complex empla es, such as pep ides, ca bon nano ubes, i uses, o cylind ical polyme b ushes (CPBs).16,19 CPBs a e molecula b ushes ca ying linea side chains densely g a ed om a backbone.20 The dense packing o side chains along he polyme backbone leads o a s eching o he backbone and a s i ening o he en i e b ush. Va ious ypes o CPBs wi h di e en s uc u es and chemical composi ions ha e been epo ed.20,21 Co e-shell o co e-shell-co ona s uc u ed CPBs ( ha is, polyme b ushes ca ying di- o iblock copolyme s as side chains) ha e p o en o be in e es ing building blocks in empla e chemis y. Th ough he incompa ibili y o he side chain blocks wi h each o he , he polyme b ush can be di ided in o wo o h ee di e en concen ic compa men s, which can be used as unimolecula empla es o nano eac o s o he syn hesis o 1D o ganic, hyb id o pu ely ino ganic nanos uc u es. Co e-shell(-co ona) CPBs wi h a deg adable co e ha e been used o o m uni o m ubula nanos uc u es.22-24 In addi ion, a polyelec oly e co e o shell o co e- shell CPBs was used o immobilize me al p ecu so s, such as Cd2+, Fe2+/Fe3+, AuCl4-, Chap e 5 – Silica Nanowi es and Nano ubes 120 P Cl6- and Ti4+ ions, and con e he p ecu so s in o he co esponding nanopa icles in he co e o he shell.16,25-31 Mo eo e , CPBs ha e been used as building blocks o he ab ica ion o o gano-silica hyb id nano ubes and nanowi es, whe e he silica p ecu so was co alen ly a ached o he empla e b ush.32,33 In he case o silica nanos uc u es, many o he abo emen ioned syn hesis ou es ha e been explo ed.34-39 Syn he ic ou es owa d silica nanos uc u es mainly depend on bo h so and ha d aniso opic empla es and in ol e mul iple s eps including he in oduc ion o silica.39 Due o di icul ies in ob aining sac i icial 1D empla es o high quali y and la ge quan i y, he wide use o silica nanos uc u es, especially nano ubes, has been g ea ly limi ed. Mo e speci ically, he p ecise con ol o he size and aspec a io, scale-up, and cos minimiza ion du ing syn hesis a e a gene al issue. As a esul , a acile syn hesis o well-de ined and size- unable silica nanowi es and nano ubes on a la ge scale is highly desi able o ully explo e hei p ac ical applica ions. Aniso opic silica-based ma e ials, in pa icula , a e a ac i e ma e ials due o hei chemical ine ness, co osion esis ance, and mechanical and he mal s abili y. He ein, we use co e-shell CPBs, consis ing o poly(ε-cap olac one) (PCL) as a co e and poly[2-(dime hylamino) e hyl me hac yla e] (PDMAEMA) as a polyca ionic shell, as a empla e o he ab ica ion o silica nanowi es and nano ubes (Scheme 5-1). The applied polyme iza ion echniques pe mi ed excellen con ol o e he syn hesis o he empla e b ushes and allowed p ecise adjus men o he aspec a io and mo phology o he 1D silica nanos uc u es. Anionic ing-opening polyme iza ion (ROP) o ε-cap olac one (CL) inc eased he g a ing e iciency and allowed he emo al o he co e- o ming block. The p ecise p oduc ion o silica nanoma e ials wi h di e en leng hs and di e en co e and shell diame e s was achie ed by loading he amine-con aining compa men wi h a silica p ecu so , namely e ame hyl o hosilica e (TMOS), and he subsequen hyd olysis and condensa ion. TMOS has al eady been used o he syn hesis o a ious silica nanos uc u es.40-42 Acid ea men o calcina ion o he PCL- illed nanowi es led o hollow silica nano ubes. Fu he mo e, we loaded he polyelec oly e shell wi h me al ions (e.g. P Cl42- o AuCl4-) and embedded he co esponding P o Au nanopa icles in o he silica shell, gi ing ca aly ically ac i e silica nanoma e ials. Chap e 5 – Silica Nanowi es and Nano ubes 121 Scheme 5-1. Syn hesis o Templa e CPBs and hei Use in he Templa e-Di ec ed Syn hesis o Silica Hyb id Nanos uc u es Expe imen al Sec ion Ma e ials. All chemicals we e o analy ical g ade and used as ecei ed wi hou u he pu i ica ion, excep o 2-(dime hylamino)e hyl me hac yla e (Ald ich, 98%), which was passed h ough a silica column p io o polyme iza ion. P epa a ion o he So Templa e Polyme B ush [CLnDMAEMAp]m. The empla e was syn hesized h ough he combina ion o anionic, ing-opening and a om ans e adical polyme iza ion. Table 5-1 p o ides an o e iew o he syn hesized polyme s and polyme b ushes. The s epwise build-up om a polyini ia o backbone o a co e-shell CPB is explained in de ail below using [CL14DMAEMA43]7500 as an example. Chap e 5 – Silica Nanowi es and Nano ubes 122 Table 5-1. O e iew o he Syn hesized Polyme Backbones and Polyme B ushes Polyme composi ion Mn [106g·mol-1] Mw/Mnc PHEMA 2700 a 0.35a 1.05 PHEMA 7500 a 0.98a 1.14 [CL 10 ] 2700 b 3.08b 1.13 [CL 25 ] 2700 b 7.70b 1.25 [CL 14 ] 7500 b 12.0b 1.40 [CL 10 DMAEMA 58 ] 2700 b 26.0b - [CL 25 DMAEMA 76 ] 2700 b 37.4b - [CL 14 DMAEMA 43 ] 7500 b 59.0b - [CL 14 DMAEMA 342 ] 7500 b 382b - a Molecula weigh as measu ed by SLS; b A de e mined by 1H-NMR; c A de e mined by SEC in DMAc. The SEC aces o he PCL b ushes can be ound in he Suppo ing In o ma ion (Fig. S1). The polyini ia o backbone poly(2-hyd oxye hyl me hac yla e) (PHEMA) was ob ained h ough he dep o ec ion o poly(2-( ime hylsiloxy)e hyl me hac yla e) (PTMS-HEMA). The backbone was syn hesized as epo ed by Mo i e al..43 Two PTMS-HEMA homopolyme s wi h di e en leng h we e syn hesized. The numbe -a e age deg ee o polyme iza ion (DPn) and he polydispe si y index (PDI) we e 7500 and 1.14 o 2700 and 1.05, espec i ely. The dep o ec ion o he TMS g oup was pe o med wi h ace ic acid in me hanol. PHEMA (80 mg, 0.62 mmol) was dissol ed in ε-cap olac one (6 mL, 54.2 mmol) and wa e aces we e emo ed ia dis illa ion in he p esence o benzene. The mix u e was hen degassed by bubbling a gon o 30 min. The ROP o CL was ca alyzed ia he addi ion o in(II)-e hylhexanoa e (1.5 mg, 3.70 µmol) a 125 °C. The polyme iza ion was allowed o p oceed o 11 h un il he mix u e became e y iscous. The polyme iza ion was quenched wi h MeOH, exposed o ai and dilu ed wi h THF. The con e sion was de e mined a e pu i ica ion wi h 1H-NMR by compa ing he polyme ic CH2-signal a 4.1 ppm and he e minal CH2-signal a 3.65 ppm. The PCL homopolyme b ush [CL14]7500 was p ecipi a ed wice in a cold wa e /me hanol mix u e (10/90 / ) and hen eeze-d ied om dioxane. [CL14]7500 was hen eac ed wi h a 1.5 old mola excess o 2-b omoisobu y yl b omide and a 2 old mola excess o ie hylamine (TEA) in d y THF o unc ionalize he PCL b ush wi h ATRP ini ia ing g oups. The eac ion mix u e was s i ed o 24 h a oom empe a u e, and hen he unc ionalized polyme was concen a ed by sol en e apo a ion, p ecipi a ed in a cold wa e /me hanol mix u e (80/20 Chap e 5 – Silica Nanowi es and Nano ubes 123 / ) and eeze-d ied om dioxane. [CL14]7500 (0.008 mmol) was dissol ed in 7 mL anisole and deoxygena ed o 10 min in a sc ew-cap lask sealed wi h a sep um. 0.01 mmol CuCl was hen added and a gon was con inued o be bubbled h ough he mix u e o 20 min. Meanwhile, 5 mmol o des abilized DMAEMA, 0.01 mmol o N,N,N′,N′′,N′′- pen ame hyldie hylene iamine (PMDETA) and 1 mL o anisole we e degassed as well. The polyme iza ion s a ed a e adding he DMAEMA/PMDETA mix u e o he eac ion lask a 50 °C. The polyme iza ion was moni o ed ia 1H-NMR and quenched a he desi ed con e sion by cooling i and exposing i o ai . The polyme solu ion was passed h ough a silica gel column be o e i was p ecipi a ed in o cold cyclohexane. The p ecipi a e was immedia ely dissol ed in e hanol and p ecipi a ed a second ime. The weigh con en o he polyme b ushes dissol ed in e hanol was de e mined be o e he solu ion was dialyzed o wa e . Qua e niza ion o [CLnDMAEMAp]m. An excess o me hyliodide (MeI) was added d op- wise o he co e-shell polyme b ushes in wa e . The solu ion became u bid immedia ely and was allowed o s i o ano he 24 h. The iscosi y inc eased signi ican ly du ing ha ime. Un eac ed MeI was emo ed unde educed p essu e. P epa a ion o Silica Hyb id Nanowi es. 100µL o e ame hyl o hosilica e (TMOS) was added d op-wise o 2 mL o he cylind ical polyme empla e in wa e (0.25 g·L-1) a 15 °C unde igo ous s i ing. The mix u e was allowed o s i o 20 min be o e i was dilu ed wi h 6 mL o e hanol. The mix u e was hen cen i uged a 12 500 c o 1 min and washed wi h e hanol and wa e , aided by ul asound. P epa a ion o Hollow Silica Nano ubes. The eeze-d ied silica hyb ids (1 mg) we e ei he mixed wi h 2M HCl and s i ed a 50 °C o h ee days o calcined as a d y powde in ai a mosphe e a 650 °C wi h a hea ing a e o 10 K·min-1. P epa a ion o he Pla inum-Doped Silica Hyb id Nanowi es. 100 µL o an aqueous solu ion o po assium e achlo opla ina e (24 mmol·L-1) was added d op-wise o 10 mL o he empla e b ush solu ion (0.25 g·L-1) unde s i ing. A e s i ing o 1 h, 2 mL o he solu ion was mixed a 15 °C wi h TMOS as desc ibed abo e. A e washing he pla inum-doped hyb id silica nanowi es, hey we e ea ed wi h 100 µL o eshly p epa ed NaBH4 (1 g·L-1) solu ion and mixed o 1 h using ul asound, be o e he NaBH4 was washed o using cen i uga ion. Chap e 5 – Silica Nanowi es and Nano ubes 124 P epa a ion o he Gold-Doped Silica Hyb id Nanowi es. 100 µL o an aqueous solu ion o chlo oau ic acid (HAuCl4) (0.3 w %) was added d op-wise o 10 mL o he empla e b ush solu ion (0.25 g·L-1) unde s i ing. A e s i ing o 1 h, 2 mL o he solu ion was mixed a 15 °C wi h TMOS as desc ibed abo e. A e washing he gold-doped hyb id silica nanowi es, hey we e ea ed wi h 100 µL o eshly p epa ed NaBH4 (1 g·L-1) solu ion and mixed o 1 h using ul asound, be o e he NaBH4 was washed o again. Reduc ion o 4-Ni ophenol Ca alyzed by Nanopa icle-Doped Silica Hyb id Nanowi es. 0.5 mL o NaBH4 solu ion (60 mmol·L-1) was added o 2.5 mL o 4-ni ophenol solu ion (0.12 mmol·L-1) ha was con ained in a glass cu e e. Then, 0.5 mL o ei he pla inum o gold nanopa icle-doped hyb id nanowi es solu ion (nanowi e concen a ion 0.001 g·L-1) was added. Immedia ely a e he addi ion o he composi e pa icles, ul a iole (UV) spec a o he sample we e aken con inuously in he ange o 250-500 nm. The a e cons an s o he eac ions we e de e mined by measu ing he change in in ensi y o he peak a 399 nm wi h ime. Cha ac e iza ion Me hods. Size Exclusion Ch oma og aphy (SEC). SEC in N, N- dime hylace amide (DMAc) wi h 0.05M li hium b omide was conduc ed a an elu ion a e o 0.7 mL·min-1 using polyes e copolyme ne wo k (GRAM) columns (300 × 8 mm, 7 µm): 103 and 102 Å and RI and UV (λ = 260 nm) de ec ion. A poly(me hyl me hac yla e) (PMMA) calib a ion cu e was used o calib a e he columns. A omic Fo ce Mic oscopy (AFM). AFM images we e eco ded on a Digi al Ins umen s Dimension 3100 mic oscope ope a ed in apping mode. The samples we e p epa ed by dip-coa ing o eshly clea ed mica in o a solu ion o he polyme b ush solu ion dilu ed in e hanol o wa e o o m a monomolecula ilm. T ansmission Elec on Mic oscopy (TEM). B igh ield TEM was pe o med using a Zeiss CEM 902 elec on mic oscope ope a ed a 80 kV. A d ople o a solu ion o he polyme b ush solu ion (0.05 g·L-1) in wa e o e hanol was d opped on o a coppe g id (200 mesh) coa ed wi h ca bon ilm, ollowed by blo ing he liquid and d ying a oom empe a u e o a sho ime. C yogenic T ansmission Elec on Mic oscopy (c yo-TEM). C yo-TEM was conduc ed by d opping he aqueous dilu e solu ion (0.1 g·L-1) on a hyd ophilized lacey TEM g id, whe e mos o he liquid was emo ed wi h blo ing pape , lea ing a hin film s e ched o e he g id holes. The specimens we e shock ozen by apid imme sion in o liquid Chap e 5 – Silica Nanowi es and Nano ubes 125 e hane and cooled o app oxima ely 90 K by liquid ni ogen in a empe a u e con olled eezing uni (Zeiss C yobox, Zeiss NTS GmbH, Obe kochen, Ge many). A e he specimens we e ozen, he emaining e hane was emo ed using blo ing pape . The specimen was inse ed in o a c yo- ans e holde (CT3500, Ga an, München, Ge many) and ans e ed o a Zeiss EM922 EF-TEM ins umen ope a ed a 200 kV. Scanning Elec on Mic oscopy (SEM) and Ene gy-Dispe si e X-Ray (EDX). SEM and EDX analysis was pe o med using a Zeiss Model 1530 Gemini ins umen equipped wi h a ield-emission ca hode wi h a la e al esolu ion o ∼ 2 nm. The samples we e measu ed on silica wa e and spu e ed wi h pla inum o 1 min. In he case o he EDX in es iga ed samples, he samples we e cen i uged, d ied, no spu e ed and di ec ly measu ed on he plain s ud wi hou silica wa e . P o on Nuclea Magne ic Resonance. 1H-NMR spec a we e eco ded o de e mine he monome con e sion on a B uke AC-300 spec ome e a oom empe a u e in CDCl3. N2-physiso p ion. N2-physiso p ion was conduc ed a 77 K on a Quan ach ome Au oso b 1 ins umen .P io o he measu emen s, he samples we e degassed a 403 K o 24 h. The hyb id nano ubes we e calcined in a ube u nace in ai a mosphe e om 30°C o 650 °C (hea ing a e 10 K min-1). p/p0 alues be ween 0.01 and 0.06 we e aken o de e mine he speci ic su ace a eas. The ecommenda ions o Rouque ol e al. ega ding he BET equa ion we e ollowed.44 Resul s and Discussion Templa e Syn hesis and Cha ac e iza ion. Co e-shell CPBs (Scheme 5-1, ii) we e used as a empla e o he ab ica ion o a ious 1D silica nanos uc u es. The polyme b ushes we e syn hesized ia he “g a ing- om” app oach, whe e side chains a e g own om a polyini ia o backbone. Poly(hyd oxye hyl me hac yla e) (PHEMA) was chosen o he backbone, as i can be used o ini ia e he anionic ROP o ε- CL. PHEMA was p oduced ia anionic polyme iza ion o TMS-HEMA and a subsequen dep o ec ion s ep wi h ace ic acid. To ob ain di e en leng hs o he la e silica hyb ids, we syn hesized wo PHEMA backbones wi h di e en molecula weigh s. The weigh -a e age molecula weigh (Mw) o bo h backbones was de e mined by s a ic ligh sca e ing (SLS; da a no shown). Di iding Mw by he espec i e PDI, ob ained om SEC, and he molecula weigh o HEMA, esul ed in he numbe -a e age deg ee o polyme iza ion (DPn) o each Chap e 5 – Silica Nanowi es and Nano ubes 126 polyme backbone, namely 2700 (PHEMA2700) and 7500 (PHEMA7500), espec i ely. PHEMA was hen used o he ROP o CL in bulk. Due o he a he high molecula weigh s o he polyol backbones, i was complica ed o d y he polyini ia o comple ely and, acco dingly, i was di icul o exclude all aces o he wa e du ing he polyme iza ion. The p esence o wa e is p oblema ic since i can also ac as an ini ia o o he ROP o CL, leading o non-g a ed poly(cap olac one) (PCL). The ROP was ca alyzed by in(II)-e hylhexanoa e and is known o ha e a e y high g a ing e iciency o abo e 90%.45 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 chemical shi (ppm) h h i i j j aa b b c c g g dioxane d d‘ d d‘ e e 3.70 3.65 Figu e 5-1. 1H-NMR spec a in CDCl3 o (A) he [CL25]2700 homopolyme b ush, (B) he end-g oup modi ied PCL b ush and (C) [CL25DMAEMA76]2700. Be o e a aching an ATRP ini a o , he as-syn hesized PCL polyme b ushes we e pu i ied om he homo-PCL by selec i e p ecipi a ion in a THF/cyclohexane mix u e. A 1H-NMR spec um o he pu i ied PCL homopolyme b ushes can be seen in Figu e 5-1A. To de e mine he DPn o PCL, we compa ed he a io o he e minal CH2-OH-g oup (d) a 3.65 ppm o he co esponding polyme ic CH2-g oup (a) a 4.1 ppm. The a io equals he DPPCL. Upon es e i ica ion, he e minal CH2-g oup shi s comple ely low ield and can be ound a 4.25 ppm (d’). This is a clea indica ion o success ul es e i ica ion. In Chap e 5 – Silica Nanowi es and Nano ubes 127 addi ion, a new peak (e) a 1.9 ppm appea s, which o igina es om he wo me hyl g oups o he 2-b omoisobu y a e g oup (Figu e 5-1B). In a inal s ep, 2-(dime hylamino)e hyl me hac yla e (DMAEMA) was g a ed om he PCL b ush o gi e wa e -soluble polyelec oly e CPBs [CLnDMAEMAp]m. PDMAEMA was chosen as i is pa ially cha ged in wa e a pH 7. I is also known ha ca ionic polyme s can p omo e localized silica deposi ion.40 The con e sion o DMAEMA was con i med by 1H-NMR. Figu e 5- 1C shows he co esponding spec um o [CL25DMAEMA76]2700 in CDCl3. To de e mine he e iciency o he g a ing o PDMAEMA, he PCL pa o he polyme b ushes was deg aded in 2 M HCl o e h ee days. The u bid b ush solu ion clea ed al eady a e se e al hou s, indica ing he success ul clea age o he PDMAEMA side chains. The SEC aces (in DMAc, wi h PDMAEMA calib a ion) o he clea ed PDMAEMA had a e y simila molecula weigh compa ed o he one ob ained om 1H-NMR (see Suppo ing In o ma ion, Figu e 5-S2). This con i ms ha he g a ing om PCL b ushes has ≥ 90% e iciency.45 The inc ease in g a ing densi y, compa ed o he g a ing om a poly(2- b omoisobu y yloxye hyl me hac yla e) (PBIEM) polyini a o (ca. 50-70%),25,33 is explained by he educed s e ical hind ance o PCL b ushes. G a ing om e y close o he backbone inc eases s e ical hind ance and hence dec eases he g a ing e iciency. PCL side chains ac as a space and he e o e inc ease he g a ing e iciency. Se e al polyme s wi h di e en dimensions, wi h espec o leng h as well as co e and shell diame e , we e syn hesized and used o he deposi ion o silica. Fou polyme b ush composi ions a e highligh ed in Table 5-2. Table 5-2. 1D Silica Hyb ids wi h Di e en Dimensions (in nm) Templa e composi iona Templa e leng hb Hyb id leng hc Co e diame e c Silica shell diame e c [CL 10 DMAEMA 58 ] 2700 295 ± 20 270 ± 15 5-6 ~25 [CL 25 DMAEMA 76 ] 2700 265 ± 20 235 ± 20 10-12 ~35 [CL 14 DMAEMA 43 ] 7500 1250 ± 200 950 ± 350 6-7 ~25 [CL 14 DMAEMA 342 ] 7500 1250 ± 200 950 ± 350d 6-7e ~ 85 a De e mined by 1H-NMR; b measu ed om AFM images o he empla e b ushes; c measu ed om TEM mic og aphs o he as-syn hesized silica hyb ids; d es ima ed om TEM mic og aphs, as i was a he di icul o di ec ly measu e he ac ual leng h due o he jamming o hai y silica nanos uc u es; e assumed o be he same dimension as wi h [CL14DMAEMA43]7500; aking in o accoun ha he co e is ~6 nm in diame e . Chap e 5 – Silica Nanowi es and Nano ubes 134 Howe e , we assume ha he co e was deg aded equally quickly, as in he deg ada ion o he p is ine PCL-b-PDMAEMA b ush and hence esul ed in hollow silica nano ubes. TEM and SEM measu emen s e i y he unchanged s uc u e o he nanoma e ials a e acid ea men (see Figu e 5-S8). Figu e 5-5. TEM mic og aphs o calcined silica nano ubes empla ed om (A-C) [CL14DMAEMA43]7500 and (D-F) [CL25DMAEMA76]2700. (A, D) Agglome a es o silica nano ubes a e calcina ion. (B, C, E, F) Sepa a ed silica nano ubes a e sonica ion. Me al-Con aining B ushes as Ca alys s. To demons a e he po en ial o he empla ed silica nanowi es in ca alysis applica ions, we loaded he PDMAEMA shell wi h me al sal s p io o he inco po a ion o silica. Thus, he addi ion o TMOS embedded he me al ions (e.g. [AuCl4]- o [P Cl4]2-) wi hin he silica shell. Excess sal was emo ed by ul acen i uga ion. The addi ion o NaBH4 as a educing agen led o he o ma ion o gold o pla inum nanopa icles (NPs). The TEM mic og aphs in Figu e 5-6 con i m he success ul inco po a ion o he nanopa icles and clea ly e i y he loca ion o he nanopa icles wi hin he silica shell. The size o he nanopa icles was measu ed ia TEM. The a e age diame e o he pla inum and gold nanopa icles is ~ 1.6 nm and ~ 3.5 nm, espec i ely. Ene gy-dispe si e X- ay measu emen s con i med he p esence o nanopa icles and showed a gold con en o 3 w % wi h espec o silicon. Fo pla inum, he con en was 4 w % (see Suppo ing In o ma ion 5-S8). The educ ion o 4-ni ophenol o 4-aminophenol by NaBH4 in he p esence o he NP- doped silica nanowi es was pe o med o check hei accessibili y and ca aly ic ac i i y. This eac ion has been used widely and has become a model eac ion o es ing he ca aly ic ac i i y o noble me al nanopa icles.30,48,49 As shown in he Suppo ing Chap e 5 – Silica Nanowi es and Nano ubes 135 In o ma ion (Figu e 5-S8), he s ong UV abso p ion o 4-ni ophena e ions a 399 nm dec eased g adually wi h ime a e he addi ion o nanopa icle-con aining hyb id nanowi es. Simul aneously, a new peak appea ed a 300 nm, which was due o he p oduc 4-aminophenol.50,51 Figu e 5-6. TEM mic og aphs o NP-doped silica hyb id nanowi es. Silica hyb id nanowi es we e illed wi h (A, C, E) Au NPs, o (B, D, F) P NPs. Magni ica ion o he nanowi es shows ha hey a e illed wi h NPs. The nanowi es we e empla ed om [CL14DMAEMA342]7500 in he case o Au NPs and om [CL14DMAEMA43]7500 in he case o P NPs. Chap e 5 – Silica Nanowi es and Nano ubes 136 Conclusions The 1D so empla e build-up o he ab ica ion o silica nanowi es was ealized ia he combina ion o se e al polyme iza ion echniques ha allowed ine- uning o he dimensions and mo phology o he hyb id nanos uc u es. CPBs p o ed o be excellen so empla es, as hei p oduc ion is s aigh o wa d and cos -e ec i e. Silica deposi ion in o he empla e shell o med 1D silica hyb id nanowi es in a mild p ocedu e in wa e a ambien empe a u e. Wi h his e sa ile ou e owa ds aniso opic silica nanos uc u es, i is possible o no only a y leng h and diame e , bu also o a y he su ace mo phology by adjus ing he shell leng h. Calcina ion o ea men wi h an acid led o he emo al o he co e and esul ed in silica nano ubes wi h high mic opo ous olumes and high speci ic su ace a eas. These ma e ials migh be in e es ing as il e o s o age sys ems. Fu he mo e, he inco po a ion o ca aly ically ac i e nanopa icles was acile and yielded obus ca alys s, which can be easily emo ed om he sys em a e he eac ion. Addi ionally, he inco po a ion o me allic NPs in o silica allows he s uc u es o be used in high empe a u e applica ions.52 These ma e ials migh also be in e es ing in he applica ion o ca aly ically ac i e il e sys ems. Associa ed con en Suppo ing In o ma ion. SEC aces o PCL b ushes (5-S1) and o clea ed PDMAEMA side chains (5-S2); AFM heigh analysis o empla e b ushes (5-S3); TEM mic og aphs o silica hyb ids om qua e nized empla es (5-S4), N2-physiso p ion measu emen s and po e olume dis ibu ions (5-S5), silica hyb ids om co e-shell-co ona empla es (5-S6); silica nano ubes ia acid ea men (5-S7); EDX spec a o pla inum and gold nanopa icle-doped hyb ids (5-S8), and ca aly ic ac i i y o nanopa icle-doped hyb ids (5-S9). This ma e ial is a ailable ee o cha ge ia he In e ne a h p://pubs.acs.o g.” Acknowledgmen s This wo k was suppo ed by he Deu sche Fo schungsgemeinscha (DFG) wi hin he Collabo a i e Resea ch Cen e (SFB) 840 and he Aus alian Resea ch Council. The au ho s hank Ma ie a Böhm and Melanie Fö sch o pe o ming SEC and c yo-TEM measu emen s, espec i ely. M. M. acknowledges BayEFG o a schola ship and BayNAT o a ellowship. T. 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Langmui 2003, 19, 5517-5521. (51) Esumi, K.; Isono, R.; Yoshimu a, T. Langmui 2003, 20, 237-243. (52) Joo, S. H.; Pa k, J. Y.; Tsung, C.-K.; Yamada, Y.; Yang, P.; Somo jai, G. A. Na . Ma e . 2009, 8, 126-131. Chap e 5 – Silica Nanowi es and Nano ubes 140 Suppo ing In o ma ion 5-S1. SEC T aces o PCL Homopolyme B ushes 13 14 15 16 17 18 19 20 Elu ione Volume (mL) [CL 14 ] 7500 [CL 25 ] 2700 [CL 10 ] 2700 Figu e 5-S1. SEC aces in DMAc o he PCL homopolyme b ushes. Chap e 5 – Silica Nanowi es and Nano ubes 141 5-S2. SEC T ace o Clea ed PDMAEMA G a s Clea ing o he PDMAEMA side chains o he empla e b ush ia acidic es e hyd olysis esul ed in a linea homopolyme PDMAEMA wi h numbe -a e age molecula weigh (Mn) o 54 x103 g·mol-1and a polydispe si y index (PDI) o 1.18 (de e mined ia SEC in DMAc and PDMAEMA calib a ion). Acco ding o he con e sion measu ed by 1H-NMR, he Mn was de e mined o be 49.5 x103 g·mol-1. This led o a g a ing e iciency o DMAEMA o 91-92%. 16 18 20 22 24 26 28 Elu ion Volume (mL) Figu e 5-S2. SEC ace in DMAc o PDMAEMA350 a e clea ing om [CL14DMAEMA350]7500 unde acidic condi ions. SEC was calib a ed wi h PDMAEMA s anda ds. Chap e 5 – Silica Nanowi es and Nano ubes 142 5-S3. Heigh Analysis o AFM Images C oss-sec ions o he a ious empla e b ushes lis ed in Table 5-2 and heigh p o iles o he espec i e polyme b ush (see Figu e 5-S3A-D). As al eady discussed in he manusc ip , he leng h o he polyme b ushes is i s ly dependen on he deg ee o polyme iza ion o he backbone. I he backbone o di e en b ushes is iden ical (see in Figu e 5-S3A and B; Figu e 5-S3C and D), hen he leng h is dependen on he b ush composi ion. The heigh in AFM inc eases when he side chain leng h inc eases, as mo e polyme ic ma e ial is deposi ed on o he subs a e (compa e Figu e 5-S3C and D). Despi e ha ing a simila o e all side chain leng h, he heigh in AFM may a y d ama ically, as can be seen in Figu e 5-S3A and B. This phenomenon is a ibu ed o he di e en size o he PCL co e. As PCL is assumed o p e en di ec con ac o mica, i will o ce he co e o be comple ely shielded by PDMAEMA. Due o ha ac , he b ush wi h a la ge PCL compa men shows an inc ease in heigh . In addi ion, his inc ease is also based on he segmen densi y o he polyme b ush. Due o he e y high g a ing e iciency, he polyme co e is su ounded by a ela i ely compac PDMAEMA shell, which adds d ama ically o he heigh in AFM (compa e ca oons in Figu e 5-S3). Chap e 5 – Silica Nanowi es and Nano ubes 143 Figu e 5-S3. AFM heigh images o a ious empla e b ushes and hei co esponding heigh p o ile (c oss- sec ion): (A) [CL10DMAEMA58]2700, (B) [CL25DMAEMA76]2700, (C) [CL14DMAEMA43]7500 and (D) [CL14DMAEMA342]7500. The z- alues a e: (A, C) 2 nm, (B) 15 nm and (D) 10 nm.