PNIPAM线性链与凝胶在二元溶剂中相变的变温NMR研究

波谱学杂志 ›› 2010, Vol. 27 ›› Issue (3): 461-469.

PNIPAM线性链与凝胶在二元溶剂中相变的变温NMR研究

王念^1, ²，茹阁英¹，王立英¹，冯继文^1*

1. 波谱与原子分子物理国家重点实验室，武汉磁共振中心（中国科学院武汉物理与数学研究所），湖北武汉 430071；
2. 中国科学院研究生院，北京 100049

收稿日期:2010-07-16 出版日期:2010-09-05 发布日期:2010-09-05

NMR Studies on Phase Separation of Linear PNIPAM and Gel in Binary Solvents

WANG Nian^{1, 2}, RU Ge-Ying¹, WANG Li-Ying¹, FENG Ji-Wen^1*

1. State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Center for Magnetic Resonance(Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences), Wuhan 430071; 2. Graduate School of Chinese Academy of Sciences, Beijing 100049

Received:2010-07-16 Online:2010-09-05 Published:2010-09-05

摘要/Abstract

摘要：

通过对聚N-异丙基丙烯酰胺（PNIPAM）水溶液和凝胶在水和甲醇混合溶剂中的¹H NMR谱图以及弛豫时间(T₁与T₂)等多种NMR参数随温度变化的研究，发现PNIPAM大分子的基团质子NMR信号、溶剂的弛豫时间都可以用来灵敏表征PNIPAM在二元溶剂中的相变行为. 在PNIPAM凝胶中，温度升到LSCT以上，溶剂峰由单峰变为双峰，分别对应于受限在大分子网络内的受限溶剂和排除到大分子网络外的自由溶剂，两者的弛豫时间存在明显差异. 在PNIPAM溶液中，溶剂峰在相变前后并没有显著变化. 通过PNIPAM溶胀在water/alcohol混合溶剂中的相变研究进一步证实了PNIPAM与不同溶剂之间的相互作用强弱. 

关键词: 核磁共振(NMR), 聚N-异丙基丙烯酰胺, 相变, 凝胶

Abstract:

In this article, the phase separation of linear PNIPAM and gel in water/methanol binary solvents was studied by the measurements of NMR spectra and relaxation times. It was found that ¹H NMR spectrum of PNIPAM, relaxation times of solvents changed dramatically when phase transition occurred. When PNIPAM gel in binary solvents was heated above the LCST only part of the solvents was expelled from the polymer networks and the other part remained inside the polymer networks, resulting in two distinct type of solution. Comparison the compositions of two distinct solution provides a convenient, direct means of characterizing the preferential adsorption of solvent on polymer. On the contrary, there was no obviously change of the solution peaks from ¹H NMR spectrum as linear PNIPAM dissolved in water/methanol binary solvents.

Key words: NMR, PNIPAM, phase transition, gel

中图分类号:

O482.53

王念, 茹阁英, 王立英, 冯继文. PNIPAM线性链与凝胶在二元溶剂中相变的变温NMR研究[J]. 波谱学杂志, 2010, 27(3): 461-469.

WANG Nian, RU Ge-Ying, WANG Li-Ying, FENG Ji-Wen. NMR Studies on Phase Separation of Linear PNIPAM and Gel in Binary Solvents[J]. Chinese Journal of Magnetic Resonance, 2010, 27(3): 461-469.

参考文献

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