Abstract

The effect of temperature on water sorption by gels based on the copolymers of N-isopropylacrylamide with sodium p-styrene sulfonate containing 1, 3, and 5 mol % of charged monomer units is studied in aqueous media in the presence of salt (NaCl, KCl) or urea. It is shown that the incubation of gels in salt solutions leads to compression of the gels. With increasing temperature, the collapse of gels is observed in all studied media. The difference in the gel collapse temperature in water and salt solution increases with an increase in the fraction of charged units in the polymer gel network and in the salt concentration in the solution. With a return temperature decrease and gel decollapse, the mass of all gels in salt solutions (0.5–5.0 wt %) is completely restored. The incubation of gels in aqueous solutions of urea (0.5–5.0 wt %) has practically no effect on water sorption by gels before the collapse and the collapse temperature. However, the degree of swelling of polyelectrolyte gels during decollapse caused by a temperature decrease is much lower than the initial value, in contrast to the completely reversible swelling of the poly(N-isopropylacrylamide) gel under similar conditions.

中文翻译：

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水性介质中热敏性聚电解质凝胶的塌陷-塌陷

摘要

温度对基于N-异丙基丙烯酰胺与p钠共聚物的凝胶的吸水率的影响在盐（NaCl，KCl）或尿素存在下，在水性介质中研究了含1、3和5摩尔％带电单体单元的-苯乙烯磺酸盐。结果表明，在盐溶液中孵育凝胶会导致凝胶压缩。随着温度的升高，在所有研究的介质中均观察到凝胶的塌陷。水和盐溶液中凝胶塌陷温度的差异随着聚合物凝胶网络中带电单元的分数增加以及溶液中盐浓度的增加而增加。随着返回温度的降低和凝胶的崩解，盐溶液中所有凝胶的质量（0.5-5.0 wt％）将完全恢复。在尿素（0.5–5.0 wt％）的水溶液中孵育凝胶实际上对凝胶在塌陷和塌陷温度之前的吸水率没有影响。然而，N-异丙基丙烯酰胺）凝胶在类似条件下使用。