华东理工大学徐小飞团队报道了表面极化对聚电解质电刷坍塌转变的影响。相关研究成果于2024年3月1日发表在《高分子科学》。

聚电解质刷（PEBs）是一种常用的表面改性方法，引起了人们的极大研究兴趣。接枝表面的介电常数通常与溶液的介电常数显著不同，这导致了具有电场跳跃的表面极化（SP）效应。因此，研究SP如何改变PEB的结构和性能是很重要的。

该文中，利用统计热力学理论研究了SP对PEB结构的影响。利用图像电荷法构造了描述SP效应的自由能函数。同时，考虑到离子溶剂化效应，用修正的Poisson-Boltzmann方程求解静电势。在不存在SP的情况下，当降低溶剂质量时，PEB的厚度表现出连续的坍塌转变。在SP存在的情况下，崩溃变成了跳跃式的转变。自由能分析表明，由于SP的存在增强了反离子的凝聚，长程库仑相互作用主导了跃迁。

该理论为研究SP对PEB的影响提供了一个有效的工具，其结果解释了PEB坍塌跃迁中的基本物理现象。

附：英文原文

Title: Surface Polarization Effects on Collapse Transition of Polyelectrolyte Brushes

Author: Xiao-Fei Xu

Issue&Volume: 2024-03-01

Abstract: Polyelectrolyte brushes (PEBs) are commonly used to modify surface that have attracted great research interest. The dielectric permittivity of the grafted surface is typically significantly different from that of solution, which results in surface polarization (SP) effect with a jump of electric field. It is thus important to study how SP alters the PEB’s structure and properties. In this work, the SP effects on PEB structure was studied using a statistical thermodynamic theory. The free energy functional to describe SP effect was constructed by using the image-charge method. Meanwhile, the electrostatic potential was solved from a modified Poisson-Boltzmann equation taking the ion solvation effect into consideration. In the absence of SP, the thickness of PEB exhibited a continuous collapse transition when decreasing the solvent quality. In the presence of SP, the collapse became a jump-like transition. Free energy analysis showed that the long-range Coulombic interaction dominated the transition because of the enhanced counterion condensation in the presence of SP. The theory provides an effective tool to study SP effect on PEBs, and the results explain the underlying physics in PEB collapse transition.

DOI: 10.1007/s10118-024-3086-8

Source: https://www.cjps.org/en/article/doi/10.1007/s10118-024-3086-8/