Dissipative Particle Dynamics for Directed Self-Assembly of Block Copolymers

TL;DR

This paper extends the dissipative particle dynamics (DPD) simulation method to accurately model the self-assembly of block copolymers in thin films and directed self-assembly, capturing complex structures and phase behaviors.

Contribution

The authors reparametrize the DPD model to better predict block copolymer self-assembly in thin films and directed systems, including complex structures.

Findings

Reproduces bulk phase behavior of block copolymers.

Predicts experimentally observed thin film structures.

Successfully models complex directed self-assembled structures.

Abstract

The dissipative particle dynamics (DPD) simulation method has been shown to be a promising tool to study self-assembly of soft matter systems. In particular, it has been used to study block copolymer (BCP) self-assembly. However, previous parametrizations of this model are not able to capture most of the rich phase behaviors of block copolymers in thin films nor in directed self-assembly (chemoepitaxy or graphoepitaxy). Here we extend the applicability of the DPD method for BCPs to make it applicable to thin films and directed self-assembly. Our new reparametrization is able to reproduce the bulk phase behavior, but also manages to predict thin film structures obtained experimentally from chemoepitaxy or graphoepitaxy. A number of different complex structures, such as bilayer nanomeshes, 90{\deg} bend structures, circular cylinders/lamellae and Frank-Kasper phases directed by trenches, post arrays or chemically patterned substrate have all been reproduced in this work. This reparametrized DPD model should serves as a powerful tool to predict BCP self-assembly, especially in some complex systems where it is difficult to implement SCFT.