水蒸气诱导聚电解质刷的构象转变
Switching of polyelectrolyte brushes by water vapor

我们把 Flory？Huggins 模型(association models)推广应用暴露于水蒸气中的聚电解质刷体系，考虑聚电解质-水氢键(P-W氢键)与水-水氢键(W-W氢键)、形成氢键与聚电解质链构象的耦合特性，研究水蒸气诱导的聚电解质刷构象转变的机理.研究发现，当 P-W 氢键效应起主导作用时，随着水蒸气浓度的增加，聚电解质刷会单调溶胀；P-W 和 W-W 两种氢键效应，则会导致随着水蒸气浓度的增加，聚电解质刷的构象首先塌缩，然后开始溶胀的反常转变行为。基于本文的分析，可以预言，由于 P-W 氢键效应，聚电解质刷可以吸附水蒸气，吸附能力随聚电解质链长的增加而增强；当聚电解质链接枝密度足够高时，由于 P-W 和 W-W 两种氢键效应，增加体系中的水蒸气，会在聚电解质刷体系中形成由 P-W 氢键和 W-W 氢键交错链接的三维网络状凝胶结构。
We presented a theory to study switching of polyelectrolyte brushes by water vapor. Our theory model include the consideration of polyelectrolyte-water(P-W) and water-water(W-W) molecules hydrogen bonds. We found that P-W hydrogen bonds become a key element in inducing swelling of polyelectrolyte brushes. Our results also indicate that the combination of P-W and W-W hydrogen bonds can result in a nonmonotonic dependence of a brush height on water vapor concentration: while the brush initially shrinks with increasing humidity until it reaches a minimum, and then it stretches with increasing humidity. Based on our theoretical model, we can predict, because of P-W of hydrogen bonds, polyelectrolyte brushes can adsorb water vapor,and adsorption capacity also increases with chain-length and brush-height;P-W and W-W hydrogen bonds hybridization will lead to a hydrogen-bond network formation of 3D polyelectrolyte brushes.