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

Abstract

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

CLC Number:

O482.53

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.

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