Co-Nonsolvency Transition of Poly(N-isopropylacrylamide) Brushes in a Series of Binary Mixtures
Co-Nonsolvency Transition of Poly(N-isopropylacrylamide) Brushes in a Series of Binary Mixtures
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DOI：
10.1021/acs.macromol.9b01286
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发表时间：
2019-08
期刊：
影响因子：
5.5
通讯作者：
Huaisong Yong;E. Bittrich;P. Uhlmann;A. Fery;J. Sommer
中科院分区：
文献类型：
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作者：
Huaisong Yong;E. Bittrich;P. Uhlmann;A. Fery;J. Sommer
如果两种良好溶剂的混合物导致聚合物在这两种溶剂的一定组成范围内坍塌或脱混成富聚合物相，则发生共不溶解。在这项工作中，我们系统地研究了不同接枝密度的聚n -异丙基丙烯酰胺刷在一系列从甲醇到1-丁醇疏水组分增加的醇-水二元混合物中的共不溶解行为。我们报告了一个强大的崩溃转变通过增加醇浓度在富水相，这是加强了长链醇。对醇-水系列的热力学性质分析表明，醇-水脱混趋势的增强与毛刷崩塌转变的增强有关。接枝密度的增加削弱了过渡行为，但没有改变最大刷体崩塌的溶剂组成点，这与一项研究的预测一致。
Co-nonsolvency occurs if a mixture of two good solvents causes the collapse or demixing of polymers into a polymer-rich phase in a certain range of compositions of these two solvents. In this work, we systematically study the co-nonsolvency behavior of poly(N-isopropylacrylamide) brushes of different grafting densities in a series of alcohol–water binary mixtures with increasing hydrophobic parts ranging from methanol to 1-butanol by using ellipsometry. We report a strong collapse transition by increasing the alcohol concentration in the water-rich phase, which is enhanced for longer-chain alcohols. The analysis of the thermodynamic properties of the alcohol–water series displays that an increasing demixing tendency between alcohol and water is correlated with an enhancement of the collapse transition of the brush. The increase of grafting density weakens the transition behavior but does not shift the solvent composition point of maximum brush collapse, which is in agreement with the predictions of a rece...