Coarse Graining in Block Copolymer Films

TL;DR

This paper explores various ordering mechanisms in block copolymer films using a coarse-graining approach, examining surface effects, roughness, and external electric fields to control morphology and phase transitions.

Contribution

It introduces a coarse-graining framework to analyze surface-induced ordering, rough surface effects, and electric field alignment in block copolymer films, including ion effects.

Findings

Surface ordering varies with temperature and surface chemistry.

Rough surfaces induce a transition from parallel to perpendicular lamellae.

Electric fields can align meso-phases and trigger phase transitions.

Abstract

We present few ordering mechanisms in block copolymer melts in the coarse-graining approach. For chemically homogeneous or modulated confining surfaces, the surface ordering is investigated above and below the order-disorder temperature. In some cases the copolymer deformation near the surface is similar to the copolymer morphology in bulk grain boundaries. Block copolymers in contact with rough surfaces are considered as well, and the transition from lamellae parallel to perpendicular to the surface is investigated as a function of surface roughness. Finally, we describe how external electric fields can be used to align block copolymer meso-phases in a desired direction, or to induce an order-order phase transition, and dwell on the role of mobile dissociated ions on the transition.