States of water in poly(vinyl alcohol) hydrogels

Polymer Gels and Networks Pub Date : 1997-01-01 Epub Date: 1999-07-07 DOI:10.1016/S0966-7822(97)00016-6

Masanobu Nagura , Naoya Takagi , Hiroshi Katakami , Yasuo Gotoh , Yutaka Ohkoshi , Tomoe Koyano , Norihiko Minoura

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引用次数: 13

Abstract

Poly(vinyl alcohol) (PVA) hydrogels with various water contents were prepared from 10 wt% aqueous solutions of mixtures of PVA and anionic poly(styrene sulfonic acid) sodium salt (NaPSS) by casting, dehydrating, and then extracting NaPSS. The existence of three types of ice were suggested by differential scanning calorimetry (DSC) measurements for every frozen hydrogel. In the frozen hydrogels the states of water, except unfrozen water, were ice of free water and disordered ice crystals. The mobility and activation energy for motion of water molecules in unfrozen hydrogels were investigated by using pulsed nuclear magnetic resonance (PNMR) measurements. It was concluded that there are two states of water in the unfrozen hydrogel, i.e. unfrozen water and disordered water which is mainly formed in narrow apertures in the hydrogel. The discrepancy between the DSC and PNMR measurements was explained by a structural transformation during cooling.

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聚乙烯醇水凝胶中水的状态

以PVA与阴离子型聚苯乙烯磺酸钠盐(NaPSS)的混合物为原料，以10 wt%的水溶液为原料，经浇铸、脱水、萃取制备了不同含水量的聚乙烯醇(PVA)水凝胶。通过差示扫描量热法(DSC)对每个冷冻水凝胶的测量，表明存在三种类型的冰。在冷冻的水凝胶中，除了未冻结的水外，水的状态是自由水的冰和无序的冰晶。利用脉冲核磁共振(PNMR)测量了水凝胶中水分子的迁移率和运动活化能。结果表明，未冻水凝胶中的水存在两种状态，即未冻水和无序水，无序水主要形成于水凝胶的窄孔中。DSC和PNMR测量值之间的差异可以用冷却过程中的结构转变来解释。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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Polymer Gels and Networks

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