Yuan Jiaxing, Wang Yanwei
School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China.
Department of Chemical and Materials Engineering, School of Engineering and Digital Sciences, Nazarbayev University, 53 Kabanbay Batyr Avenue, Nur-Sultan 010000, Kazakhstan.
J Phys Chem B. 2021 Sep 23;125(37):10589-10596. doi: 10.1021/acs.jpcb.1c04451. Epub 2021 Sep 8.
Understanding the structural response of weak polyelectrolyte brushes upon external stimuli is crucial for their applications ranging from modifying surface properties to the development of smart and intelligent materials. In this work, coarse-grained molecular dynamics simulations were carried out to investigate the conformation and ionization behavior of charge-regulating polyelectrolyte brushes under poor solvent conditions, using an implicit solvent model. The results show that, while the thickness of a sparse polyelectrolyte brush shows a similar behavior to that of a single chain, namely, a monotonic change as a function of solvent quality (modeled by an effective segment-segment attraction strength parameter) and solution pH, a dense polyelectrolyte brush exhibits more complex behavior. An unexpected reexpansion is observed when the effective segment-segment attraction strength is further increased, especially in the case of a high pH. In the latter case, strong attraction in polymer segments promotes the formation of large, interchain, cylindrical aggregates, leading to an increase in brush thickness.
了解弱聚电解质刷在外部刺激下的结构响应对于其从修饰表面性质到智能材料开发等一系列应用至关重要。在这项工作中，使用隐式溶剂模型进行了粗粒度分子动力学模拟，以研究电荷调节聚电解质刷在不良溶剂条件下的构象和电离行为。结果表明，虽然稀疏聚电解质刷的厚度表现出与单链类似的行为，即作为溶剂质量（由有效链段-链段吸引强度参数建模）和溶液pH的函数呈单调变化，但致密聚电解质刷表现出更复杂的行为。当有效链段-链段吸引强度进一步增加时，尤其是在高pH情况下，会观察到意外的再膨胀。在后一种情况下，聚合物链段中的强吸引力促进了大的链间圆柱形聚集体的形成，导致刷厚度增加。
