Instabilities and disorder of the domain patterns in the systems with competing interactions

TL;DR

This paper investigates the stability of domain patterns in systems with competing interactions, focusing on how certain instabilities can lead to disorder in microphase-separated diblock copolymer systems near transition points.

Contribution

It introduces a criterion for the validity of mean field theory and identifies specific instabilities causing disorder in hexagonal domain patterns.

Findings

Ordered hexagonal patterns become unstable at certain temperatures.

Two types of instabilities lead to pattern disorder: radial distortions and order parameter repumping.

Disorder arises from these instabilities transforming regular patterns into disordered ones.

Abstract

The dynamics of the domains is studied in a two-dimensional model of the microphase separation of diblock copolymers in the vicinity of the transition. A criterion for the validity of the mean field theory is derived. It is shown that at certain temperatures the ordered hexagonal pattern becomes unstable with respect to the two types of instabilities: the radially-nonsymmetric distortions of the domains and the repumping of the order parameter between the neighbors. Both these instabilities may lead to the transformation of the regular hexagonal pattern into a disordered pattern.