Lattice model study of the thermodynamic interplay of polymer crystallization and liquid-liquid demixing

TL;DR

This study uses lattice-polymer Monte Carlo simulations to explore how isotropic and anisotropic interactions influence the phase behavior of semiflexible homopolymer solutions, revealing interplay between crystallization and demixing.

Contribution

It introduces a lattice-polymer model that simultaneously captures polymer crystallization and liquid-liquid demixing, and demonstrates their interaction through simulations and theoretical analysis.

Findings

Isotropic interactions affect the freezing curve.

Anisotropic interactions influence demixing.

Demixing disappears below the freezing curve when isotropic interactions weaken.

Abstract

We report Monte Carlo simulations of a lattice-polymer model that can account for both polymer crystallization and liquid-liquid demixing in solutions of semiflexible homopolymers. In our model, neighboring polymer segments can have isotropic interactions that affect demixing, and anisotropic interactions that are responsible for freezing. However, our simulations show that the isotropic interactions also have a noticeable effect on the freezing curve, as do the anisotropic interactions on demixing. As the relative strength of the isotropic interactions is reduced, the liquid-liquid demixing transition disappears below the freezing curve. A simple, extended Flory-Huggins theory accounts quite well for the phase behavior observed in the simulations.