Interdigitation between surface-anchored polymer chains and an elastomer : consequences for adhesion promotion

TL;DR

This paper develops an analytical model to understand how grafted polymer chains interdigitate with elastomers, revealing a critical grafting density that influences adhesion strength, supported by comparison with experimental data.

Contribution

It introduces a partial interdigitation model predicting a critical grafting density for interdigitation cessation, linking theory with adhesion measurements.

Findings

Critical grafting density $\sigma^{*}$ predicted as $ ext{P}^{1/10} N^{-3/5}$.

Interdigitation ceases beyond the critical density, affecting adhesion.

Model aligns with recent experimental adhesion data.

Abstract

We study the adhesion between a cross-linked elastomer and a flat solid surface where polymer chains have been end-grafted. To understand the adhesive feature of such a system, one has to study both the origin of the grafted layer interdigitation with the network, and the end-grafted chains extraction out of the elastomer when it comes unstuck from the solid surface. We shall tackle here the first aspect for which we develop a partial interdigitation model that lets us analytically predict a critical surface grafting density $\sigma^{*} \simeq P^{{1/10}}N^{-{3/5}}$ beyond which the layer no longer interdigitates with the elastomer. We then relate this result with recent adhesion measurements.