Multiscale modeling of solute diffusion in triblock copolymer membranes

TL;DR

This paper presents a multiscale simulation framework combining self-consistent field theory and kinetic Monte Carlo to predict solute diffusion in triblock copolymer membranes, providing a systematic and adaptable modeling approach.

Contribution

The work introduces a novel multiscale modeling approach that integrates SCFT and kMC simulations to accurately predict solute diffusion in complex polymer membrane structures.

Findings

The model accurately predicts solute diffusivity in triblock copolymer membranes.

It outperforms simple lattice random walk models in robustness and parameterization.

The approach can be extended to various chemistries and morphologies.

Abstract

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.