Tension, rigidity and preferential curvature of interfaces between coexisting polymer solutions

TL;DR

This paper models the interface properties between coexisting polymer solutions, revealing how curvature influences stability and interfacial tension, with implications for understanding phase separation in polymer systems.

Contribution

It introduces a blob model-based calculation of interface properties in polymer solutions, including curvature effects and stability predictions for phase-separated droplets.

Findings

Interfaces exhibit preferential curvature stabilizing low molecular mass polymer droplets.

Calculated interfacial tensions and rigidities match experimental predictions.

Curvature effects influence phase stability in polymer solutions.

Abstract

The properties of the interface in a phase-separated solution of polymers with different degrees of polymerization and Kuhn segment lengths are calculated. The starting point is the planar interface, the profile of which is calculated in the so-called 'blob model', which incorporates the solvent in an implicit way. The next step is the study of a metastable droplet phase formed by imposing a chemical potential different from that at coexistence. The pressure difference across the curved interface, which corresponds to this higher chemical potential, is used to calculate the curvature properties of the droplet. Interfacial tensions, Tolman lengths and rigidities are calculated and used for predictions for a realistic experimental case. The results suggest that interfaces between phase-separated solutions of polymers exhibit, in general, a preferential curvature, which stabilizes droplets of low molecular mass polymer in a high molecular mass macroscopic phase.