Phase diagram for diblock copolymer melts under cylindrical confinement

TL;DR

This paper explores the phase diagram of diblock copolymer melts confined in cylindrical nanopores, revealing new equilibrium structures and phase transitions influenced by pore size, with implications for experimental observations.

Contribution

It introduces a comprehensive phase diagram for confined diblock copolymers, discovering novel structures not seen in unconfined systems and mapping their stability regions.

Findings

Identification of new two-dimensional equilibrium structures

Structural transitions as pore radius decreases

Predictions of phases yet to be experimentally observed

Abstract

We extensively study the phase diagram of a diblock copolymer melt confined in a cylindrical nanopore using real-space self-consistent mean-field theory. We discover a rich variety of new two-dimensional equilibrium structures that have no analog in the unconfined system. These include non-hexagonally coordinated cylinder phases and structures intermediate between lamellae and cylinders. We map the stability regions and phase boundaries for all the structures we find. As the pore radius is decreased, the pore accommodates fewer cylindrical domains and structural transitions occur as cylinders are eliminated. Our results are consistent with experiments, but we also predict phases yet to be observed.