Co-Nonsolvency of Poly(n-isopropylacrylamide) in Deuterated Water/Ethanol Mixtures

被引：106

作者：

Hore, Michael J. A. ^{[1
]}

Hammouda, Boualem ^{[1
]}

Li, Yuyan ^{[2
]}

Cheng, He ^{[2
]}

机构：

[1] NIST, Ctr Neutron Res, Gaithersburg, MD 20899 USA

[2] Chinese Acad Sci, Inst Chem, State Key Lab Polymer Phys & Chem, Beijing 100190, Peoples R China

来源：

MACROMOLECULES | 2013年 / 46卷 / 19期

基金：

美国国家科学基金会;

关键词：

MIXED-SOLVENTS; WATER/METHANOL MIXTURE; RAFT POLYMERIZATION; AQUEOUS-SOLUTIONS; PHASE-BEHAVIOR; WATER; TRANSITION; CONONSOLVENCY; TEMPERATURE; DYNAMICS;

D O I：

10.1021/ma401665h

中图分类号：

O63 [高分子化学（高聚物）];

学科分类号：

070305 ; 080501 ; 081704 ;

摘要：

Small-angle neutron scattering was used to investigate poly(N-isopropylacrylamide) (PNIPAM) polymer solutions in d-water/d-ethanol mixtures. A wide poor-solvent region was observed for mixtures near 60% d-water/40% d-ethanol mixture. Spinodal lines were determined, permitting a mapping of the mixing/demixing regions of the phase diagram which comprises two main branches: the left branch (with mostly d-ethanol) where phase separation occurs upon cooling (UCST) and the right branch (with mostly d-water) where phase separation occurs upon heating (LCST). The ternary random phase approximation model was used to analyze SANS data. Three Flory-Huggins interaction parameters (PNIPAM/d-water, PNIPAM/d-ethanol and d-water/d-ethanol) were obtained. These display the reassuring 1/T behavior but show strong dependence on d-water/d-ethanol fraction. The conformation of polymer chains was determined by monitoring of the radius of gyration. Chains tend to swell with increasing temperature except close to the boundary of the left branch of the phase diagram (40% d-water) where they are observed to shrink.

引用

页码：7894 / 7901

页数：8

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