Demixing of compact polymers chains in three dimensions

TL;DR

This paper introduces an efficient Monte Carlo algorithm for sampling polymer melts, revealing that two chains tend to phase separate in large three-dimensional lattices, with demixing becoming more pronounced as aspect ratio increases.

Contribution

The paper presents a novel Monte Carlo algorithm for unbiased sampling of polymer melts and demonstrates the demixing phenomenon in three-dimensional lattice models.

Findings

Two chains phase separate in large lattices.

Demixing occurs even at aspect ratio r=1.

Demixing becomes more pronounced with increasing r.

Abstract

We present a Monte Carlo algorithm that provides efficient and unbiased sampling of polymer melts consisting of two chains of equal length that jointly visit all the sites of a cubic lattice with rod geometry L x L x rL and non-periodic (hard wall) boundary conditions. Using this algorithm for chains of length up to 40 000 monomers and aspect ratios 1 <= r <= 10, we show that in the limit of a large lattice the two chains phase separate. This demixing phenomenon is present already for r=1, and becomes more pronounced, albeit not perfect, as r is increased.