Hybrid Lattice Boltzmann / Dynamic Self-Consistent Field Simulations of Microphase Separation and Vesicle Formation in Block Copolymer Systems

TL;DR

This paper introduces a hybrid simulation method combining lattice Boltzmann and self-consistent field techniques to study hydrodynamics in polymer systems, revealing effects on microphase separation and vesicle formation.

Contribution

It develops a novel hybrid numerical approach integrating hydrodynamics into SCF simulations for inhomogeneous polymers, enabling detailed analysis of dynamic processes.

Findings

Hydrodynamics accelerate late-stage structure formation.

Hydrodynamics influence vesicle formation pathways.

Little effect on early microphase separation.

Abstract

We present a hybrid numerical method to introduce hydrodynamics in dynamic self-consistent field (SCF) studies of inhomogeneous polymer systems. It solves a set of coupled dynamical equations: The Navier-Stokes equations for the fluid flow, and SCF-based convection-diffusion equations for the evolution of the local monomer compositions. The Navier-Stokes equaitons are simulated by the lattice Boltzmann method and the dynamic self-consistent equations are solved by a finite difference scheme. Two applications are presented: First, we study microphase separation in symmetric and asymmetric block copolymer melts with various values of shear and bulk viscosities, comparing the results to those obtaiuned with purely diffusive dynamics. Second, we investigate the effect of hydrodynamics on vesicle formation in amphiphilic block copolymer solutions. In agreement with previous studies, hydrodynamic interactions are found to have little effect on the microphase separation at early times, buty they substantially accelerate the process of structure formation at later times. Furthermore, they also contribute to selecting the pathway of vesicle formation, favoring spherical intermediates over aspherical (disklike) ones.