Soft particle model for block copolymers

TL;DR

This paper introduces a soft particle model for diblock copolymer melts, combining analytical and simulation methods to study microphase ordering, diffusion, and pattern transfer in thin films at mesoscopic scales.

Contribution

It presents a novel soft particle model that effectively captures the structural and kinetic properties of copolymers, bridging analytical expressions with Monte Carlo simulations.

Findings

Model accurately describes microphase ordering kinetics.

Soft particle approach captures diffusion and pattern transfer.

Suitable for mesoscopic scale simulations of copolymer systems.

Abstract

A soft particle model for diblock (AB) copolymer melts is proposed. Each molecule is mapped onto two soft spheres built by Gaussian A- and B-monomer distributions. An approximate analytical expression for the joint distribution function for the distance between both spheres and their radii of gyration is derived, which determines the entropic contribution to the intramolecular free energy. Adding a mean-field expression for the intermolecular interactions, we obtain the total free energy of the system. Based on this free energy, Monte Carlo simulations are carried out to study the kinetics of microphase ordering in the bulk and its effect on molecular diffusion. This is followed by an analysis of thin films with emphasis on pattern transfer from walls with a periodic structure. It is shown that the level of coarse graining in the soft particle model is suitable to describe structural and kinetic properties of copolymers on mesoscopic scales.