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

摘要

We present a hybrid numerical method to introduce hydrodynamics in dynamicself-consistent field (SCF) studies of inhomogeneous polymer systems. It solvesa set of coupled dynamical equations: The Navier-Stokes equations for the fluidflow, and SCF-based convection-diffusion equations for the evolution of thelocal monomer compositions. The Navier-Stokes equaitons are simulated by thelattice Boltzmann method and the dynamic self-consistent equations are solvedby a finite difference scheme. Two applications are presented: First, we studymicrophase separation in symmetric and asymmetric block copolymer melts withvarious values of shear and bulk viscosities, comparing the results to thoseobtaiuned with purely diffusive dynamics. Second, we investigate the effect ofhydrodynamics on vesicle formation in amphiphilic block copolymer solutions. Inagreement with previous studies, hydrodynamic interactions are found to havelittle effect on the microphase separation at early times, buty theysubstantially accelerate the process of structure formation at later times.Furthermore, they also contribute to selecting the pathway of vesicleformation, favoring spherical intermediates over aspherical (disklike) ones.