We develop a multiscale simulation model for diffusion of solutes through porous triblock copolymer membranes. The approach combines two techniques: self-consistent field theory (SCFT) to predict the structure of the self-assembled, solvated membrane and on-lattice kinetic Monte Carlo (kMC) simulations to model diffusion of solutes. Solvation is simulated in SCFT by constraining the glassy membrane matrix while relaxing the brush-like membrane pore coating against the solvent. The kMC simulations capture the resulting solute spatial distribution and concentration-dependent local diffusivity in the polymer-coated pores; we parameterize the latter using particle-based simulations. We apply our approach to simulate solute diffusion through nonequilibrium morphologies of a model triblock copolymer, and we correlate diffusivity with structural descriptors of the morphologies. We also compare the model's predictions to alternative approaches based on simple lattice random walks and find our multiscale model to be more robust and systematic to parameterize. Our multiscale modeling approach is general and can be readily extended in the future to other chemistries, morphologies, and models for the local solute diffusivity and interactions with the membrane.

中文翻译：

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三嵌段共聚物膜中溶质扩散的多尺度建模

我们开发了一个多尺度模拟模型，用于溶质通过多孔三嵌段共聚物膜的扩散。该方法结合了两种技术：用于预测自组装溶剂化膜结构的自洽场论 (SCFT) 和用于模拟溶质扩散的晶格动力学蒙特卡罗 (kMC) 模拟。在 SCFT 中，通过约束玻璃状膜基质，同时放松刷状膜孔涂层对溶剂的作用来模拟溶剂化。kMC 模拟捕获了聚合物涂层孔隙中产生的溶质空间分布和浓度相关的局部扩散率；我们使用基于粒子的模拟对后者进行参数化。我们应用我们的方法通过模型三嵌段共聚物的非平衡形态模拟溶质扩散，我们将扩散率与形态的结构描述符相关联。我们还将模型的预测与基于简单格随机游走的替代方法进行了比较，发现我们的多尺度模型更稳健、更系统地进行参数化。我们的多尺度建模方法是通用的，并且可以在未来很容易地扩展到其他化学、形态和局部溶质扩散率和与膜相互作用的模型。