Influence of Chain Interdiffusion Between Immiscible Polymers on Dewetting Dynamics

TL;DR

This study reveals that chain interdiffusion between immiscible polymers PS and PDMS significantly affects dewetting behavior and interface properties, with diffusion occurring below PS's glass transition temperature and influenced by grafting density.

Contribution

It demonstrates the unexpected diffusion of PS chains into PDMS brushes below PS's glass transition and links interdiffusion to dewetting dynamics and interface aging.

Findings

PS chains diffuse into PDMS brushes below glass transition temperature

Interdiffusion influences friction and dewetting behavior

Interface modifications explain aging of PS thin films

Abstract

The interface between two immiscible polymers, polystyrene (PS) and polydimethylsiloxane (PDMS), was studied by neutron reflectivity and dewetting by using free PS chains and PDMS brushes. Unexpectedly, we found that the PS chains diffuse in the PDMS brushes at temperatures well below the glass transition temperatures of PS, the dynamics being largely determined by the grafting density of the brush. By this study, we demonstrate the major influence of the chains interdiffusion on the friction properties for a couple of immiscible polymers. By the way, the puzzling ageing of PS thin films observed from dewetting experiments is found to be directly related to modifications of the PS/PDMS interface.