Phase behavior of correlated random copolymers

TL;DR

This paper develops a method to calculate phase diagrams of correlated random copolymers considering realistic chain lengths, composition, and blockiness, revealing how these factors influence phase behavior and fractionation effects.

Contribution

It introduces a novel approach combining distribution functions and the method of moments to analyze phase behavior of correlated random copolymers with realistic chain lengths.

Findings

Transition points depend on copolymer composition and blockiness.

Fractionation significantly affects phase diagram appearance.

The method accurately predicts phase coexistence in statistical copolymers.

Abstract

In this work, Flory-Huggins phase diagrams for correlated random copolymers with realistic chain lengths are calculated. This is achieved in two steps. At first we derive a distribution function of copolymer chains with respect to composition and blockiness. Then we used the method of moments, which was developed by Sollich and Cates [Sollich, P.; Cates, M. E.; Phys. Rev. Lett. 1998, 80, 1365-1368] for polydisperse systems, to reduce the number of degrees of freedom of the computational problem and calculate phase diagrams. We explored how location of transition points and composition of coexisting phases depend on copolymer composition, blockiness and degree of polymerisation. The proposed approach allows to take into account fractionation, which was shown to have effect on the appearance of phase diagrams of statistical copolymers.