New aspects in the phase behaviour of poly-N-isopropyl acrylamide: systematic temperature dependent shrinking of PNiPAM assemblies well beyond the LCST

被引：103

作者：

Bischofberger, Irmgard ^{[1
]}

Trappe, Veronique ^{[1
]}

机构：

[1] Univ Fribourg, Dept Phys, CH-1700 Fribourg, Switzerland

来源：

SCIENTIFIC REPORTS | 2015年 / 5卷

基金：

瑞士国家科学基金会;

关键词：

DILUTE AQUEOUS-SOLUTIONS; THERMORESPONSIVE POLYMERS; GLOBULE TRANSITION; POLY(N-ISOPROPYLACRYLAMIDE); MESOGLOBULES; HYDRATION; WATER; SEPARATION; KINETICS; CHAIN;

D O I：

10.1038/srep15520

中图分类号：

O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];

学科分类号：

07 ; 0710 ; 09 ;

摘要：

We investigate the phase behaviour of aqueous dispersions of poly-N-isopropyl acrylamide (PNiPAM) microgels above their lower critical solution temperature (LCST) and find that beyond a well-defined concentration the systems exhibit a peculiar behaviour: the microgels assemble into space-spanning gels that shrink in time while maintaining the shape of the container in which they have been formed. Over a wide range of concentrations this shrinking behaviour is independent of PNiPAM concentration, but systematically depends on temperature in a temperature range significantly exceeding the LCST. The overall shrinking characteristics are consistent with those expected for scaffolds made of materials that exhibit thermal contraction. However, for the PNiPAM assemblies contraction is irreversible and can be as large as 90%. Such characteristics disclose complex interactions between fully collapsed PNiPAM and water well beyond the LCST, the origin of which has yet to be elucidated.

引用

页数：10

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