Effect of long range forces on the interfacial profiles in thin binary polymer films

TL;DR

This study investigates how long-range surface forces influence the interfacial structure and properties of thin binary polymer films, revealing modifications to interfacial width and tension through simulations and theoretical calculations.

Contribution

It provides a comprehensive analysis combining Monte Carlo simulations and self-consistent field calculations to understand surface force effects on polymer interfaces.

Findings

Surface fields reduce intrinsic interfacial width.

Decreasing film thickness increases effective interfacial tension.

Capillary wave broadening does not follow simple logarithmic behavior.

Abstract

We study the effect of surface fields on the interfacial properties of a binary polymer melt confined between two parallel walls. Each wall attracts a different component of the blend by a non-retarded van der Waals potential. An interface which runs parallel to the surfaces is stabilized in the center of the film. Using extensive Monte Carlo simulations we study the interfacial properties as a function of the film thickness, the strength of the surface forces and the lateral size over which the profiles across the film are averaged. We find evidence for capillary wave broadening of the apparent interfacial profiles. However, the apparent interfacial width cannot be described quantitatively by a simple logarithmic dependence on the film thickness. The Monte Carlo simulations reveal that the surface fields give rise to an additional reduction of the intrinsic interfacial width and an increase of the effective interfacial tension upon decreasing the film thickness. These modifications of the intrinsic interfacial properties are confirmed by self-consistent field calculations. Taking account of the thickness dependence of the intrinsic interfacial properties and the capillary wave broadening, we can describe our simulation results quantitatively.