Merlitz Holger, Li Chengwu, Wu Chenxu, Sommer Jens-Uwe
Department of Physics and ITPA, Xiamen University, Xiamen 361005, P. R. China.
Soft Matter. 2015 Jul 28;11(28):5688-96. doi: 10.1039/c5sm01275a.
A mean-field model is developed to predict the layer-thickness of sparse and salt-free polyelectrolyte brushes, exposed to an external electric field, which attracts the polyelectrolytes to the substrate. In molecular dynamics simulations, it is shown that a fraction of polymers collapses entirely to screen the charge of the substrate. The remaining brushes are then treated as field-free brushes at reduced grafting density. The mean-field model may thus be applied to field-free brushes, both in their osmotic and their weak charge regimes. It yields simple, closed equations for the brush height and for the partition of counterions in- and outside the brushes, and accurately reproduces simulation data of the collapse of the brushes during the crossover between both charge regimes.
开发了一种平均场模型，用于预测暴露于外部电场的稀疏且无盐的聚电解质刷的层厚度，该电场会将聚电解质吸引到基底上。在分子动力学模拟中，结果表明一部分聚合物会完全塌陷以屏蔽基底的电荷。然后将剩余的刷子视为接枝密度降低的无场刷子。因此，平均场模型可应用于无场刷子，无论是在其渗透状态还是弱电荷状态。它给出了关于刷子高度以及刷子内外抗衡离子分配的简单封闭方程，并准确再现了两种电荷状态转变期间刷子塌陷的模拟数据。
