Effect of the Hofmeister anions upon the swelling of a self-assembled pH-responsive hydrogel.
Effect of the Hofmeister anions upon the swelling of a self-assembled pH-responsive hydrogel.
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DOI：
10.1021/la100339f
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发表时间：
2010-04
期刊：
影响因子：
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通讯作者：
Joshua M. G. Swann;W. Bras;P. Topham;J. Howse;A. Ryan
中科院分区：
文献类型：
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作者：
Joshua M. G. Swann;W. Bras;P. Topham;J. Howse;A. Ryan
我们报道了一系列一价钠盐对简单合成微相分离聚(甲基丙烯酸甲酯)-嵌段-聚(2-(二乙氨基)乙基甲基丙烯酸酯)-嵌段-聚(甲基丙烯酸甲酯)(PMMA(88)-b-PDEA(223)-b-PMMA(88))pH响应性水凝胶的分子平衡溶胀的影响。选择乙酸钠、氯化钠、溴化钠、碘化钠、硝酸钠和硫氰酸钠在受控的离子强度和pH下进行研究；所有盐均取自霍夫迈斯特系列 (HS)。发现阴离子对水凝胶膨胀的影响遵循经典 HS 的相反顺序。发现在含有简单卤化钠盐（NaCl、NaBr 和 NaI）的溶液中测量的凝胶膨胀率与描述离子与水相互作用的参数密切相关；表面电荷密度、粘度系数和水合熵。一项还包括非球形离子（NaAce、NaNO(3) 和 NaSCN）的全球研究表明，与粘度系数的相关性最强。我们的结果根据柯林斯模型进行解释，其中较大的离子在紧邻凝胶的第一个水合笼中具有更多的流动水，因此使它们更粘附于凝胶固定相的表面，并最终降低膨胀水平。
We report the effect of a range of monovalent sodium salts on the molecular equilibrium swelling of a simple synthetic microphase separated poly(methyl methacrylate)-block-poly(2-(diethylamino)ethyl methacrylate)-block-poly(methyl methacrylate) (PMMA(88)-b-PDEA(223)-b-PMMA(88)) pH-responsive hydrogel. Sodium acetate, sodium chloride, sodium bromide, sodium iodide, sodium nitrate and sodium thiocyanate were selected for study at controlled ionic strength and pH; all salts are taken from the Hofmeister series (HS). The influence of the anions on the expansion of the hydrogel was found to follow the reverse order of the classical HS. The expansion ratio of the gel measured in solutions containing the simple sodium halide salts (NaCl, NaBr, and NaI) was found to be strongly related to parameters which describe the interaction of the ion with water; surface charge density, viscosity coefficient, and entropy of hydration. A global study which also included nonspherical ions (NaAce, NaNO(3) and NaSCN) showed the strongest correlation with the viscosity coefficient. Our results are interpreted in terms of the Collins model, where larger ions have more mobile water in the first hydration cage immediately surrounding the gel, therefore making them more adhesive to the surface of the stationary phase of the gel and ultimately reducing the level of expansion.