Characterization of Free, Restricted, and Entrapped Water Environments in Poly(N-isopropyl acrylamide) Hydrogels via 1H HRMAS PFG NMR Spectroscopy

被引：29

作者：

Alam, Todd M. ^{[1
]}

Childress, Kimberly K. ^{[1
]}

Pastoor, Kevin ^{[2
]}

Rice, Charles V. ^{[2
]}

机构：

[1] Sandia Natl Labs, Dept Elect Opt & Nanostruct Mat, Albuquerque, NM 87123 USA

[2] Univ Oklahoma, Stephenson Life Sci Res Ctr, Dept Chem & Biochem, Norman, OK 73019 USA

来源：

JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS | 2014年 / 52卷 / 23期

基金：

美国能源部; 美国国家科学基金会;

关键词：

diffusion; HRMAS; hydrogels; NMR; PFG; stimuli-sensitive polymers; thermoresponsive polymer; water; PHASE-TRANSITION THERMODYNAMICS; N-ISOPROPYLACRYLAMIDE NIPAAM; GELS; HYDRATION; DIFFUSION; STATE; DEHYDRATION; RELAXATION; SEPARATION; PRESSURE;

D O I：

10.1002/polb.23591

中图分类号：

O63 [高分子化学（高聚物）];

学科分类号：

070305 ; 080501 ; 081704 ;

摘要：

Different water environments in poly(N-isopropyl acrylamide) (PNIPAAm) hydrogels are identified and characterized using H-1 high resolution magic angle spinning (HRMAS) nuclear magnetic resonance (NMR). Local water environments corresponding to a free highly mobile species, along with waters showing restricted dynamics are resolved in these swollen hydro-gels. For photo-initiated polymerized PNIPAAm gels, an additional entrapped water species is observed. Spin-spin R-2 relaxation experiments support the argument of reduced mobility in the restricted and entrapped water species. By combining pulse field gradient techniques with HRMAS NMR it is possible to directly measure the self-diffusion rate for these different water environments. The behavior of the heterogeneous water environments through the lower critical solution temperature transition is described. (c) 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 52, 1521-1527

引用

页码：1521 / 1527

页数：7

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