# Interface repulsion and lamellar structures in thin films of homopolymer blends due to thermal oscillations

## TL;DR

This paper shows that thermal oscillations can induce repulsive interactions between interfaces in homopolymer blends, leading to controlled lamellar structures in thin films, contrasting with the naturally attractive interface potential in equilibrium.

## Contribution

It introduces a method to control interface distances in homopolymer blends through thermal oscillations, resulting in novel lamellar structures.

## Key findings

- Oscillations induce periodic modulation of interface potential.
- Interface repulsion occurs at specific oscillation parameters.
- Lamellar structures form with multiple interfaces in thin films.

## Abstract

In equilibrium the interface potential that describes the interaction between two AB interfaces in a binary blend of A and B homopolymers is attractive at all distances, resulting in coarsening of the blend morphology even in the absence of interface curvature. We demonstrate that the dissipative assembly in response to a time-periodic variation of the blend incompatibility qualitatively alters this behavior, i.e., for suitable parameters the interface potential exhibits a periodic spatial modulation and AB interfaces adopt a well-defined distance. We explore for which oscillation periods and amplitudes an interface repulsion occurs and demonstrate that we can control the preferred interface distance over a wide range by varying the oscillation period. Using particle-based simulations we explicitly demonstrate that this dissipative assembly of a homopolymer blend results in a lamellar structure with multiple planar interfaces in a thin film geometry.