Borreguero Jose M, Pincus Philip A, Sumpter Bobby G, Goswami Monojoy
Neutron Data Analysis & Visualization, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
Department of Material Science, University of California , Santa Barbara, California 93106, United States.
J Phys Chem B. 2017 Jul 20;121(28):6958-6968. doi: 10.1021/acs.jpcb.7b05047. Epub 2017 Jul 6.
Structure-property relationships of ionic block copolymer (BCP) surfactant complexes are critical toward the progress of favorable engineering design of efficient charge-transport materials. In this article, molecular dynamics simulations are used to understand the dynamics of charged-neutral BCP and surfactant complexes. The dynamics are examined for two different systems: charged-neutral double-hydrophilic and hydrophobic-hydrophilic block copolymers with oppositely charged surfactant moieties. The dynamics of the surfactant head, tails, and charges are studied for five different BCP volume fractions. We observe that the dynamics of the different species solely depend on the balance between electrostatic and entropic interactions between the charged species and the neutral monomers. The favorable hydrophobic-hydrophobic interactions and the unfavorable hydrophobic-hydrophilic interactions determine the mobilities of the monomers. The dynamical properties of the charge species influence complex formation. Structural relaxations exhibit length-scale dependent behavior, with slower relaxation at the radius of gyration length-scale and faster relaxation at the segmental length-scale, consistent with previous results. The dynamical analysis correlates ion-exchange kinetics to the self-assembly behavior of the complexes.
离子嵌段共聚物（BCP）表面活性剂复合物的结构-性能关系对于高效电荷传输材料的良好工程设计进展至关重要。在本文中，分子动力学模拟用于理解带电-中性BCP和表面活性剂复合物的动力学。针对两个不同的体系研究了动力学：具有相反电荷表面活性剂部分的带电-中性双亲水和疏水-亲水嵌段共聚物。针对五种不同的BCP体积分数研究了表面活性剂头部、尾部和电荷的动力学。我们观察到不同物种的动力学仅取决于带电物种与中性单体之间静电相互作用和熵相互作用的平衡。有利的疏水-疏水相互作用和不利的疏水-亲水相互作用决定了单体的迁移率。电荷物种的动力学性质影响复合物的形成。结构弛豫表现出长度尺度依赖性行为，在回转半径长度尺度处弛豫较慢，在链段长度尺度处弛豫较快，这与先前的结果一致。动力学分析将离子交换动力学与复合物的自组装行为相关联。
