Humidity-Induced Phase Transitions in Ion-Containing Block Copolymer Membranes

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• 作者：Moon Jeong Park ; Alisyn J. Nedoma ; Phillip L. Geissler ; Nitash P. Balsara ; Andrew Jackson ; David Cookson
• 刊名：Macromolecules
• 出版年：2008
• 出版时间：March 25, 2008
• 年：2008
• 卷：41
• 期：6
• 页码：2271 - 2277
• 全文大小：467K
• 年卷期：v.41,no.6(March 25, 2008)
• ISSN：1520-5835

文摘

The phase behavior of ion-containing block copolymer membranes in equilibrium with humidifiedair is studied as a function of the relative humidity (RH) of the surrounding air, ion content of the copolymer,and temperature. Increasing RH at constant temperature results in both disorder-to-order and order-to-ordertransitions. In-situ small-angle neutron scattering experiments on the open block copolymer system, when combinedwith water uptake measurement, indicate that the disorder-to-order transition is driven by an increase in thepartial molar entropy of the water molecules in the ordered phase relative to that in the disordered phase. Thisis in contrast to most systems wherein increasing entropy results in stabilization of the disordered phase.