Intrinsic profiles and capillary waves at homopolymer interfaces: a Monte Carlo study

TL;DR

This study uses Monte Carlo simulations to test the concept of intrinsic profiles at homopolymer interfaces, comparing simulation results with self-consistent field theory predictions to understand interfacial structure.

Contribution

It demonstrates how to select a coarse graining length to match interfacial widths and validates the intrinsic profile concept against theoretical models.

Findings

Intrinsic profiles can be aligned with self-consistent field profiles by choosing an appropriate coarse graining length.

The intrinsic profile concept is supported by simulation results that agree with theoretical predictions.

The interfacial width can be tuned to match theoretical models through coarse graining.

Abstract

A popular concept which describes the structure of polymer interfaces by ``intrinsic profiles'' centered around a two dimensional surface, the ``local interface position'', is tested by extensive Monte Carlo simulations of interfaces between demixed homopolymer phases in symmetric binary (AB) homopolymer blends, using the bond fluctuation model. The simulations are done in an LxLxD geometry. The interface is forced to run parallel to the LxL planes by imposing periodic boundary conditions in these directions and fixed boundary conditions in the D direction, with one side favoring A and the other side favoring B. Intrinsic profiles are calculated as a function of the ``coarse graining length'' B by splitting the system into columns of size BxBxD and averaging in each column over profiles relative to the local interface position. The results are compared to predictions of the self-consistent field theory. It is shown that the coarse graining length can be chosen such that the interfacial width matches that of the self-consistent field profiles, and that for this choice of B the ``intrinsic'' profiles compare well with the theoretical predictions.