Sensing adsorption kinetics through slip velocity measurements of polymer melts

TL;DR

This study measures how slip behavior of PDMS melts evolves over time on a grafted surface, linking it to adsorption kinetics and demonstrating the slow chain adsorption as the cause.

Contribution

It provides a novel method to sense adsorption kinetics via slip velocity measurements and links slip evolution to chain adsorption dynamics.

Findings

Critical shear rate increases with time.

Slip evolution explained by slow chain adsorption.

Adsorption kinetics measured independently.

Abstract

The evolution over time of the non-linear slip behavior of a polydimethylsiloxane (PDMS) polymer melt on a weakly adsorbing surface made of short non-entangled PDMS chains densely end-grafted to the surface of a fused silica prism has been measured. The critical shear rate at which the melt enters the nonlinear slip regime has been shown to increase with time. The adsorption kinetics of the melt on the same surface has been determined independently using ellipsometry. We show that the evolution of slip can be explained by the slow adsorption of melt chains using the Brochard-de Gennes's model.