Dynamic Self-Consistent Field Theory for Unentangled Homopolymer Fluids

TL;DR

This paper introduces a lattice-based dynamic self-consistent field theory for modeling the structure, dynamics, and rheology of inhomogeneous, compressible melts and blends of unentangled homopolymer chains, capturing interfacial phenomena and flow effects.

Contribution

It develops a novel lattice formulation of DSCF theory that accounts for flow and interfacial structure in unentangled homopolymer fluids using a self-consistent field approach.

Findings

Models interfacial structure and flow in polymer melts.

Incorporates flow effects with FENE-P dumbbells.

Provides a self-consistent framework for polymer dynamics.

Abstract

We present a lattice formulation of a dynamic self-consistent field (DSCF) theory that is capable of resolving interfacial structure, dynamics and rheology in inhomogeneous, compressible melts and blends of unentangled homopolymer chains. The joint probability distribution of all the Kuhn segments in the fluid, interacting with adjacent segments and walls, is approximated by a product of one-body probabilities for free segments interacting solely with an external potential field that is determined self-consistently. The effect of flow on ideal chain conformations is modeled with FENE-P dumbbells, and related to stepping probabilities in a random walk. Free segment and stepping probabilities generate statistical weights for chain conformations in a self-consistent field, and determine local volume fractions of chain segments. Flux balance across unit lattice cells yields mean-field transport equations for the evolution of free segment probabilities and of momentum densities on the Kuhn length scale. Diffusive and viscous contributions to the fluxes arise from segmental hops modeled as a Markov process, with transition rates reflecting changes in segmental interaction, kinetic energy, and entropic contributions to the free energy under flow.