Capillary-Wave and Chain-Length Effects at Polymer/Polymer Interfaces

TL;DR

This study uses a bead-spring model to analyze how chain length and capillary waves influence the interface structure and surface tension in immiscible polymer blends, providing a new measurement method for interfacial width.

Contribution

It introduces a universal method for measuring interfacial width based on second moments and verifies its effectiveness in polymer interface analysis.

Findings

Capillary waves enable surface tension measurement.

Chain length affects surface tension.

Proposed interfacial width measurement is validated.

Abstract

A continuum-space bead-spring model is used to study the phase behavior of binary blends of homopolymers and the structure of the interface between the two immiscible phases. The structure of the interface is investigated as a function of immiscibility, chain length, and system size. Capillary waves are observed and their measurement allows us to determine the surface tension $\gamma$. We propose a more universal method of measuring the interfacial width in terms of second moments of the different contributions to the first derivative of the interfacial profile. Predictions of this method are directly verified. The effect of chain length on the surface tension is also studied.