Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, USA.
Department of Chemical Engineering, University of California, Santa Barbara, California 93106, USA.
J Chem Phys. 2020 Jan 7;152(1):014904. doi: 10.1063/1.5128119.
Understanding the transport properties of water in self-assembled block copolymer morphologies is important for furthering the use of such materials as water-purifying membranes. In this study, we used coarse-grained dissipative particle dynamics simulations to clarify the influence of pore morphology on the self-diffusion of water in linear-triblock-copolymer membranes. We considered representative lamellar, cylindrical, and gyroid morphologies and present results for both the global and local diffusivities of water in the pores. Our results suggest that the diffusivity of water in the confined, polymer-coated pores differs from that in the unconfined bulk. Explicitly, in confinement, the mobility of water is reduced by the hydrodynamic friction arising from the hydrophilic blocks coating the pore walls. We demonstrate that in lamella and cylindrical morphologies, the latter effects can be rendered as a universal function of the pore size relative to the brush height of the hydrophilic blocks.
了解自组装嵌段共聚物形态中水分子的输运性质对于进一步将此类材料用作水净化膜具有重要意义。在本研究中，我们使用粗粒耗散粒子动力学模拟澄清了孔形态对线性三嵌段共聚物膜中水分子自扩散的影响。我们考虑了代表性的层状、圆柱状和双连通胞状形态，并给出了孔中水分子整体和局部扩散率的结果。我们的结果表明，受限聚合物涂覆孔中水分子的扩散率与无约束的本体不同。具体来说，在受限情况下，壁面亲水嵌段的水动力摩擦导致水的迁移率降低。我们证明在层状和圆柱状形态中，后一种效应可以表示为孔尺寸相对于亲水嵌段的刷高的通用函数。
