Equilibrium microstructures of diblock copolymers under 3D confinement

TL;DR

This paper uses advanced simulations to study how the shape of 3D confinement geometries affects the equilibrium microstructures of diblock copolymers, revealing shape-dependent structural transitions and stability regimes.

Contribution

It introduces a flexible finite-element SCFT framework to analyze diblock copolymer microstructures in arbitrary 3D geometries, highlighting shape effects on phase behavior.

Findings

Transition from interconnected networks to concentric shells with decreasing curvature

Microstructure stability depends on length scale relative to geometry

Shape influences possible frustrated phases in confined diblock copolymers

Abstract

We investigate equilibrium microstructures exhibited by diblock copolymers in confined 3D geometries. We perform Self-Consistent Field Theory (SCFT) simulations using a finite-element based computational framework (Ackerman et al. 2017), that provides the flexibility to compute equilibrium structures under arbitrary geometries. We consider a sequence of 3D geometries (tetrahedron to sphere) that have the same volume but exhibit varying curvature. This allows us to study the interplay between edge and curvature effects of the 3D geometries on the equilibrium microstructures. We observe that beyond a length scale, the equilibrium structure changes from an interconnected network to a multi-layered concentric shell as the curvature of the 3D geometry is reduced. However, below this length scale the equilibrium structure remains a multi-layered concentric shell independent of curvature. We additionally explore variations in the equilibrium microstructures at a few discrete volume fractions. This study provides insight into possible frustrated phases that can arise in AB diblock systems while varying the shape of confinement geometry.