1
Fab ica ion o The mo- esponsi e Co on Fab ics Using 1
Poly( inyl cap olac am-co-hyd oxye hyl ac ylamide) 2
Copolyme 3
4
Min Xiao1, Edu ne González 1, Alexis Ma ell Mon e oza2, Ma ga e F ey1,* 5
6
1Depa men o Fibe Science & Appa el Design, Co nell Uni e si y, I haca NY 14850, USA 7
2Depa men o Chemis y & Chemical Biology, Co nell Uni e si y, I haca NY 14850, USA 8
9
Abs ac 10
A he mo- esponsi e polyme wi h hyd ophilic o hyd ophobic ansi ion beha io , 11
poly( inyl cap olac am-co-hyd oxye hyl ac ylamide) (P(VCL-co-HEAA)), was p epa ed 12
by copolyme iza ion o inyl cap olac am and N-hyd oxye hyl ac ylamide ia ee adical 13
solu ion polyme iza ion. The esul ing copolyme was cha ac e ized by Fou ie ans o m 14
in a ed spec oscopy (FTIR), 1H nuclea magne ic esonance (NMR), gel pe mea ion 15
ch oma og aphy (GPC), di e en ial scanning calo ime y (DSC) and he mog a ime ic 16
analysis (TGA). The lowe c i ical solu ion empe a u e (LCST) o P(VCL-co-HEAA) 17
was de e mined a 34.5°C. This he mo- esponsi e polyme was hen g a ed on o co on 18
ab ics using 1,2,3,4-bu ane e aca boxylic acid (BTCA) as c osslinke and sodium 19
hypophosphi e (SHP) as ca alys . FTIR and ene gy dispe si e X- ay spec oscopy (EDS) 20
s udies con i med he success ul g a ing eac ion. The modi ied co on ab ic exhibi ed 21
he mo- esponsi e beha io as e idenced by wa e apo pe meabili y measu emen 22
con i ming dec eased pe meabili y a ele a ed empe a u e. This is he i s demons a ion 23
ha a PVCL based copolyme is g a ed o co on ab ics. This s udy p o ides a new 24
he mo- esponsi e polyme o ab ica ion o sma co on ab ics wi h he mally 25
swi chable hyd ophilici y. 26
27
Keywo ds: he mo- esponsi e polyme , poly( inyl cap olac am) (PVCL), LCST, wa e 28
apo pe meabili y, sma co on ab ic 29
30
* Co esponding au ho . Tel.:+1-607-255-193731
32
Email add ess: m w24@co nell.edu 33
34
This is he accep ed manusc ip o he a icle ha appea ed in inal o m in Ca bohyd a e Polyme s 174 : 626-632 (2017),
which has been published in inal o m a h ps://doi.o g/10.1016/j.ca bpol.2017.06.092. © 2017 Else ie unde CC BY-
NC-ND license (h p://c ea i ecommons.o g/licenses/by-nc-nd/4.0/)
2
1. In oduc ion 35
Co on ab ics ha e many desi able p ope ies, which include high abso bency, com o , 36
dyeabili y and low cos . Co on consis s o nea ly 99% cellulose and he hyd oxyl g oups 37
(-OH) a ailable on he cellulose backbone ha e been used in a ie y o modi ica ion 38
s a egies o impa a new unc ionali y o co on ab ic, such as w inkle esis ance and 39
an imic obial p ope ies. In ecen yea s, an eme ging modi ica ion s a egy has been 40
cen e ed on g a ing s imuli- esponsi e polyme ma e ials on o cellulose-based na u al 41
ibe s o c ea e ma e ials ha can espond o changes ( empe a u e, pH o ligh ) in he 42
en i onmen (S ua e al., 2010; Yang, Es e es, Zhu, Wang, & Xin, 2012). A pa icula 43
esea ch in e es is c ea ion o he mo- esponsi e sma ex iles wi h po en ial 44
applica ions in skin ca e p oduc s, wound d essing p oduc s, sma pe meabili y, 45
deodo an ab ics, e e sible we abili y and physiological pa ame e moni o ing (Hu, 46
Meng, Li, & Ibekwe, 2012). 47
The mo- esponsi e o empe a u e-sensi i e polyme s a e a kind o sma ma e ials ha 48
espond o changes in empe a u e and unde go a phase ansi ion a he lowe c i ical 49
solu ion empe a u e (LCST) (De Las He as Ala cón, Pennadam, & Alexande , 2005). A 50
empe a u es below LCST, hese mac omolecules a e hyd ophilic and soluble in wa e 51
due o he dominan hyd ogen bonding be ween hyd ophilic segmen s o he polyme 52
chain and wa e molecules. Al e na i ely, a empe a u es abo e LCST, hese 53
mac omolecules become hyd ophobic and phase sepa a e in wa e due o he s eng hened 54
hyd ophobic in e ac ions among hyd ophobic segmen s (I an M Okhapkin, I ina R 55
Nasimo a, Elena E Makhae a, & Alexei R Khokhlo , 2003; Qiu & Pa k, 2001). While 56
mos polyme s inc ease hei wa e solubili y as he empe a u e inc eases, polyme s wi h 57
an LCST dec ease hei wa e solubili y as he empe a u e inc eases. 58
Poly (N-isop opylac ylamide) (PNIPAm) and poly( inyl cap olac am) (PVCL) a e 59
a ac i e he mo esponsi e polyme s wi h LCST in he ange o physiological 60
empe a u e, a p ope y which makes hem especially a ac i e o po en ial use in d ug 61
deli e y, biochemis y, bioenginee ing o senso s (Bae, Okano, Hsu, & Kim, 1987; 62
Schmaljohann, 2006). Al hough PNIPAm has been mo e widely s udied, he use o PVCL 63
3
is a be e al e na i e o bioapplica ions due o i s highe biocompa ibili y (Co ez-Lemus 64
& Licea-Cla e ie, 2016). 65
G a ing o PNIPAAm o co on ab ics has al eady been epo ed by a ew au ho s (T. 66
Chen, Fang, Zhong, Chen, & Wang, 2015; Wang e al., 2016). Howe e , o ou 67
knowledge, his is he i s demons a ion ha a PVCL based copolyme is used o 68
manu ac u e sma ab ics. In his s udy, we syn hesize and immobilize he mo-69
esponsi e copolyme poly( inyl cap olac am-co-hyd oxye hyl ac ylamide), P(VCL-co-70
HEAA), on o co on o ob ain he mally swi chable hyd ophilici y. Hyd oxye hyl 71
ac ylamide (HEAA) is used as co-monome in o de o add –OH unc ional g oups o he 72
copolyme . These –OH g oups a e able o g a he copolyme o co on ab ics ia a 73
ca boxylic acid-based c osslinke (BTCA). Fu he mo e, i should be no ed ha PHEAA 74
is also biocompa ible and has been widely used o biomedical applica ions (Zhang, Chu, 75
Zheng, Kissel, & Aga wal, 2012). The p ope ies o he copolyme a e cha ac e ized by 76
FTIR, 1H NMR, GPC, DSC and TGA. The lowe c i ical solu ion empe a u e (LCST) is 77
also de e mined. FTIR and EDS s udies a e conduc ed o con i m he g a ing eac ion, 78
and scanning elec on mic oscopy (SEM) is used o s udy he su ace mo phology o 79
modi ied co on. Addi ionally, he he mo- esponsi e beha io o he esul ing co on 80
ab ic is in es iga ed h ough wa e apo pe meabili y measu emen . 81
82
2. Expe imen al 83
2.1 Ma e ials 84
S anda d desized, scou ed, and bleached plain wo en co on ab ics (densi y 110 g/m2) 85
we e pu chased om Tes ab ics, Inc.. Vinyl cap olac am (VCL), 2,2’-azobis(2-me hyl-86
p opioni ile) (AIBN), dime hyl o mamide (DMF), die hyl e he , 1,2,3,4-87
Bu ane e aca boxylic acid (BTCA), and sodium hypophosphi e monohyd a e (SHP) 88
we e all pu chased om Sigma Ald ich. N-(2-Hyd oxye hyl) ac ylamide (HEAA) was 89
supplied by San a C uz Bio echnology. Deu e ium oxide (D2O) was pu chased om 90
Camb idge Iso ope Labo a o ies, Inc.. All chemicals we e used as ecei ed wi hou 91
u he pu i ica ion. 92
4
2.2 Syn hesis o P(VCL-co-HEAA) copolyme 93
P(VCL-co-HEAA) copolyme was syn hesized by copolyme izing inyl cap olac am 94
(VCL) and hyd oxye hyl ac ylamide (HEAA) ia ee adical polyme iza ion using AIBN 95
as ini ia o and DMF as sol en . Reac ions we e pe o med in a h ee neck ound bo om 96
lask equipped wi h a e lux condense and a N2 inle . The ini ial eed mola a io o VCL 97
o HEAA was 80:20. Fi s , HEAA (16.10g, 140 mmol), VCL (77.84 g, 560 mmol) and 98
DMF (345 mL) we e added o he lask. The empe a u e was inc eased o 60 °C and he 99
eac ion mix u e was s i ed o 15 minu es unde N2 low un il all componen s we e 100
comple ely dissol ed. Then, AIBN ini ia o (0.57 g, 3.5 mmol) was ho oughly dissol ed 101
in 5 mL o DMF and hen injec ed in o he lask o s a he polyme iza ion. The eac ions 102
we e pe o med a 60°C o 16 hou s unde con inuous N2 low. Polyme iza ion was 103
s opped by cooling down he eac ion o oom empe a u e. A e wa ds, he polyme was 104
p ecipi a ed in die hyl e he , il e ed and d ied in a acuum o en a 50 °C o e nigh . 105
2.3 Cha ac e iza ion o P(VCL-co-HEAA) copolyme 106
2.3.1 1H Nuclea magne ic esonance (NMR) 107
The 1H-NMR expe imen o he copolyme was eco ded a oom empe a u e wi h an 108
INOVA 400 spec ome e ope a ing a 400 MHz and using D2O as sol en . 109
2.3.2 Gel pe mea ion ch oma og aphy (GPC) 110
The molecula weigh o he P(VCL-co-HEAA) copolyme was measu ed by a Wa e s 111
ambien - empe a u e GPC equipped wi h a Wa e s 1515 isoc a ic HPLC pump and a 112
Wa e s 2414 e ac i e index de ec o a 50°C. Dime hyl o mamide (DMF) wi h 0.1% 113
li hium b omide was used as mobile phase a a low a e o 0.5 mL/min. The ob ained 114
molecula weigh alue was e e ed o polys y ene s anda ds. 115
2.3.3 The mog a ime ic analysis (TGA) 116
The mog a ime ic analysis (TGA) o he P(VCL-co-HEAA) copolyme was pe o med 117
om 30 o 800°C a a hea ing a e o 10°C /min using a ni ogen pu ge on TGA Q500, 118
TA Ins umen s. 119
2.3.4 Di e en ial scanning calo ime y (DSC) 120
The mog am o he copolyme was acqui ed wi h a TA ins umen s DSC Q2000. The 121
5
p ocedu e included a hea /cool/hea sequence a a a e o 10°C/min in he empe a u e 122
be ween 0°C and 300°C o emo e any e ec o he mal his o y. 123
2.3.5 Lowes c i ical solu ion empe a u e (LCST) 124
The lowe c i ical solu ion empe a u e (LCST) o P(VCL-co-HEAA) in aqueous solu ion 125
was measu ed on a Spec amax 384 spec opho ome e . Op ical ansmi ance o 1 w % 126
polyme solu ion in wa e was measu ed a 500 nm as a unc ion o empe a u e. The 127
LCST alue o he polyme was de e mined a he empe a u e showing an op ical 128
ansmi ance o 50%. 129
2.4 G a ing o P(VCL-co-HEAA) o co on ab ics 130
G a ing o P(VCL-co-HEAA) o co on ab ics was pe o med using BTCA as 131
c osslinke and SHP as ca alys . A solu ion was p epa ed wi h 250g/L, 20g/L, and 30g/L 132
concen a ions o P(VCL-co-HEAA), BTCA, and SHP, espec i ely. Each co on sample 133
was soaked in he solu ion o e nigh a oom empe a u e and hen padded in a labo a o y 134
padde wi h wo dips and wo nips o each a we pickup o (120±5)%. The sample was 135
d ied a 85°C o 10 min and hen cu ed in an o en a 160°C o 20 min. Finally, he 136
sample was insed wi h deionized wa e and ai -d ied in a condi ioning oom 137
(21.0±2.0°C, 65.0±4.0% ela i e humidi y) o 24 h. 138
2.5 Cha ac e iza ion o he mo- esponsi e co on ab ics 139
2.5.1 Add-on 140
The weigh o he condi ioned co on ab ics was eco ded be o e and a e he g a ing 141
p ocess. The add-on o he he mo- esponsi e co on ab ics was calcula ed as he ela i e 142
weigh inc ease o he ab ic as shown in he ollowing equa ion. 143
Add-on (%) = (𝑚𝑚𝑓𝑓−𝑚𝑚0
𝑚𝑚0) × 100 (1) 144
whe e 𝑚𝑚0 is he ini ial weigh o he ab ic and 𝑚𝑚𝑓𝑓 is he inal weigh o he ab ic g a ed 145
wi h P(VCL-co-HEAA). 146
2.5.2 FTIR 147
The Fou ie ans o m in a ed (FTIR) spec a o co on ab ics we e collec ed on a FTIR 148
spec ome e (Magna 560, Nicole Ins umen Technologies, Fi chbu g, WI, USA) using 149
6
a diamond a enua ed o al e lec ance (ATR) accesso y. The da a we e a e aged o e 64 150
scans wi h a esolu ion o 4 cm-1 in he ange o 4000 o 600 cm-1 o each sample. 151
2.5.3 SEM-EDS s udies 152
The su ace mo phology o co on ab ics was examined on a ield emission scanning 153
elec on mic oscope (LEO 1550 FESEM). The samples we e moun ed on aluminum s ubs 154
and spu e -coa ed wi h gold and scanned a 5 kV o SEM imaging. Ene gy dispe si e 155
X- ay spec oscopy (EDS) s udy was conduc ed o analyze he elemen al composi ions o 156
co on ab ics a e g a ing wi h P(VCL-co-HEAA) copolyme . 157
2.5.4 Wa e apo pe meabili y (WVP) measu emen s 158
Wa e apo pe meabili y o he modi ied co on ab ics was measu ed in acco dance wi h 159
BS 7209:1990 Tes Me hod. B ie ly, he es co on ab ic was sealed o e he open mou h 160
o a es dish which con ains wa e , and he assembly placed in a con olled a mosphe e. 161
O e a pe iod o ime, successi e weigh ings o he assembled dish we e made and he 162
a e o wa e apo pe mea ion h ough he es ab ic was de e mined. Six es ab ics 163
( h ee o ea ed samples and h ee o un ea ed samples) we e es ed in a simila manne 164
and concu en ly o de e mine WVP a oom empe a u e (21°C) and also a 50°C. 165
3. Resul s and discussion 166
3.1 Syn hesis and cha ac e iza ion o P(VCL-co-HEAA) copolyme 167
7
168
Figu e 1. 1H-NMR o P(VCL-co-HEAA) copolyme 169
0100 200 300 400 500 600 700 800
0
20
40
60
80
100
P(VCL-co-HEAA)
PVCL
Tempe a u e (
0
C)
Weigh (%)
170
(a) 171
8
050 100 150 200 250 300
-1.0
-0.5
0.0
0.5
P(VCL-co-HEAA)
PVCL
Tempe a u e (
0
C)
Hea Flow (W/g)
172
(b) 173
174
(c) 175
Figu e 2. (a) TGA he mog ams o PVCL and P(VCL-co-HEAA) copolyme ; (b) DSC 176
he mog ams o PVCL and P(VCL-co-HEAA) copolyme . The second hea ing cycle o a 177
hea /cool/hea sequence is shown; (c) T ansmi ance o PVCL and P(VCL-co-HEAA) copolyme in 178
an aqueous solu ion as a unc ion o empe a u e. 179
9
Ini ial concen a ion o monome s and hei eac i i y a ios a ec composi ions o a 180
copolyme . Figu e 1 is 1H-NMR spec um o P(VCL-co-HEAA) copolyme using D2O 181
as he sol en . The mola composi ion o he copolyme was de e mined by in eg a ing 182
he peaks co esponding o VCL p o ons a 4.2 ppm (a) and HEAA p o ons a 3.5 ppm 183
(b). A eed monome a io o 80/20 mol % VCL/HEAA yielded a 51/49 mol % 184
VCL/HEAA in he inal copolyme . This is a ibu ed o he low eac i i y a io o PVCL 185
as shown by o he au ho s (I an M. Okhapkin, I ina R. Nasimo a, Elena E. Makhae a, 186
& Alexei R. Khokhlo , 2003; Shah, Pal, Gude, & De i, 2010). The mo e eac i e HEAA 187
monome was p e e en ially inco po a ed in o he copolyme e en a a lowe eeding a io 188
o VCL. The weigh a e age molecula weigh (Mw) o P(VCL-co-HEAA) copolyme 189
was de e mined by GPC o be 10,0551 g/mol wi h a polydispe si y alue o 1.9. 190
The he mal p ope ies o PVCL and P(VCL-co-HEAA) copolyme we e analyzed by 191
TGA s udies, as shown in Figu e 2(a). The ini ial weigh loss was due o he libe a ion o 192
abso bed mois u e. The sha p weigh dec ease was associa ed wi h he he mal 193
deg ada ion o he polyme . The TGA he mog ams showed ha he syn hesized 194
copolyme had a decomposi ion empe a u e o up o 420°C. In con as , PVCL 195
decomposed a 428°C. This sugges ed ha he addi ion o he hyd ophilic comonome 196
HEAA did no a ec he he mal s abili y o he copolyme ema kably. P(VCL-co-197
HEAA) is he mally s able o he subsequen pad-d y-cu e inishing p ocess whe e he 198
g a ing eac ion wi h cellulose was achie ed a 160°C. 199
The glass- ansi ion empe a u es (Tg) o PVCL and P(VCL-co-HEAA) copolyme we e 200
shown in Figu e 2(b) and de e mined o 190°C and 160°C espec i ely. In oducing he 201
hyd ophilic comonome HEAA in o he copolyme led o a dec ease in he Tg. This can 202
enhance he c osslinking eac ion be ween cellulose, he c osslinke and he copolyme 203
in ha he molecula chains o he copolyme s a s o mo e a empe a u es abo e Tg, 204
leading o an inc eased con ac wi h cellulose and he c osslinke . 205
Figu e 2(c) shows he he mo- esponsi e beha io o PVCL and he copolyme . The 206
LCST o he polyme was co ela ed wi h he empe a u e dependen phase sepa a ion o 207
he polyme and de e mined by moni o ing he op ical ansmi ance change as a unc ion 208
16
Figu e 6 shows he weigh loss o modi ied and unmodi ied co on ab ics as a unc ion 301
o ime a oom empe a u e (21°C) and also a 50°C. The weigh loss alue was he 302
a e age o h ee es ab ics wi h a s anda d de ia ion o less han 1mg. The slope o he 303
cu e is he a e o wa e apo pe mea ion h ough he es ab ic. Based on equa ions 304
(2) and (3), he WVP alues we e calcula ed and shown in Table 2. The co ela ion 305
coe icien (R2) a e all g ea e han 0.999, indica ing a good linea eg ession i ing. The 306
WVP s udies demons a ed ha a oom empe a u e, P(VCL-co-HEAA) copolyme 307
exhibi ed hyd ophilici y and he modi ied co on ab ics beha ed simila ly o he 308
un ea ed co on ab ic wi h simila a e o wa e apo pe mea ion h ough he ab ic and 309
he e o e simila WVP. A 50°C, he copolyme unde wen phase ansi ion esul ing om 310
agg ega ion o he chain molecules due o he in e molecula in e ac ions be ween he 311
hyd ophobic g oups a ele a ed empe a u e. The g a ed co on ab ics swi ched om 312
hyd ophilic o hyd ophobic. The e o e, he ea ed co on ab ics exhibi ed lowe a e o 313
wa e apo pe mea ion and also WVP han he un ea ed co on. I is also wo hy o poin 314
ou ha 6.7 w % add-on o he ab ic ea ed wi h 150g/L o he copolyme was su icien 315
enough o achie e he same wa e apo pe meabili y wi h he ab ic ea ed wi h 250g/L 316
o he copolyme . This he mally swi chable hyd ophilici y o co on ab ic makes i 317
applicable o p o ec i e clo hing and o he sma ex iles. 318
319
Table 2. Wa e apo pe meabili y o co on ab ics ea ed wi h P(VCL-co-HEAA) copolyme 320
Concen a ion
Wa e apo pe meabili y (g/m2/day)
Room Tempe a u e
(50°C)
Slope
(mg/h)
R2
WVP
Slope
(mg/h)
R2
WVP
0 (con ol)
150 g/L
0.157
0.151
0.9991
0.9996
695
669
0.417
0.306
0.9984
0.9983
1849
1362
200 g/L
0.157
0.9998
697
0.306
0.9982
1359
250 g/L
0.146
0.9993
649
0.308
0.9915
1367
321
4. Conclusions 322
A he mo- esponsi e copolyme P(VCL-co-HEAA) was syn hesized by ee adical 323
polyme iza ion a 60°C. A eed monome a io o 80/20 mol %VCL/HEAA yielded a 324
17
51/49 mol % o a io o VCL/HEAA in he copolyme due o a highe eac i i y o HEAA. 325
The copolyme had a glass ansi ion empe a u e o 160°C and a decomposi ion 326
empe a u e o up o 420°C as e idenced by DSC and TGA s udies. The LCST alue o 327
he copolyme was 34.5°C. The mo- esponsi e co on ab ics we e success ully 328
ab ica ed by a g a ing eac ion using BTAC as c osslinke and SHP as ca alys . FTIR 329
and EDS s udies con i med he deposi ion o P(VCL-co-HEAA) copolyme on o co on. 330
The modi ied ab ics exhibi ed empe a u e- esponsi e beha io in he wa e apo 331
pe meabili y measu emen s. Compa ed o he unmodi ied co on, 6.7 w % add-on o he 332
ab ic g a ed wi h he copolyme was su icien enough o exhibi dec eased wa e 333
pe meabili y a ele a ed empe a u e due o hyd ophilic o hyd ophobic ansi ion. This 334
s udy p o ides ano he al e na i e o ab ica ion o sma ex iles and applica ion in 335
unc ional clo hing. 336
337
Acknowledgemen s 338
This wo k was suppo ed by he USDA Na ional Ins i u e o Food and Ag icul u e, Ha ch 339
p ojec NYS-329402 and Ha ch mul is a e p ojec NC-1194 NYC-329816. Any opinions, 340
indings, conclusions, o ecommenda ions exp essed in his publica ion a e hose o he 341
au ho (s) and do no necessa ily e lec he iew o he Na ional Ins i u e o Food and 342
Ag icul u e (NIFA) o he Uni ed S a es Depa men o Ag icul u e (USDA). This wo k 343
made use o he Co nell Cen e o Ma e ials Resea ch Sha ed Facili ies which a e 344
suppo ed h ough he NSF MRSEC p og am (DMR-1120296) and he Co nell NMR 345
acili y suppo ed in pa by he NSF MRI p og am (CHE-1531632). This wo k also made 346
use o he Nanobio echnology Cen e sha ed esea ch acili ies a Co nell. 347
348
Re e ences 349
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481-485. 352
Chen, S.-C., Wu, Y.-C., Mi, F.-L., Lin, Y.-H., Yu, L.-C., & Sung, H.-W. (2004). A no el pH-sensi i e 353
hyd ogel composed o N, O-ca boxyme hyl chi osan and algina e c oss-linked by genipin 354
18
o p o ein d ug deli e y. Jou nal o Con olled Release, 96(2), 285-300. 355
Chen, T., Fang, Q., Zhong, Q., Chen, Y., & Wang, J. (2015). Syn hesis and he mosensi i e 356
beha io o polyac ylamide copolyme s and hei applica ions in sma ex iles. 357
Polyme s, 7(5), 909-920. 358
Co ez-Lemus, N. A., & Licea-Cla e ie, A. (2016). Poly (N- inylcap olac am), a comp ehensi e 359
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