Frictional dissipation of polymeric solids vs interfacial glass transition

TL;DR

This study investigates how the frictional behavior at polymer-glass interfaces changes with interaction strength, revealing an interfacial glass transition influenced by pressure, which alters the shear response from viscous to solid-like.

Contribution

It introduces the concept of an interaction-induced interfacial glass transition in polymer-glass contacts, supported by experimental friction data.

Findings

Friction response varies from viscous to solid-like with increasing interaction strength.

Interfacial shear localization shifts from viscous threshold to plastic deformation.

Pressure facilitates the interfacial glass transition.

Abstract

We present single contact friction experiments between a glassy polymer and smooth silica substrates grafted with alkylsilane layers of different coverage densities and morphologies. This allows us to adjust the polymer/substrate interaction strength. We find that, when going from weak to strong interaction, the response of the interfacial junction where shear localizes evolves from that of a highly viscous threshold fluid to that of a plastically deformed glassy solid. This we analyse as resulting from an interaction-induced ``interfacial glass transition'' helped by pressure.