Mechanical tunning of adhesion through micro-patterning of elastic surfaces

TL;DR

This paper investigates how micropatterning elastic surfaces like PDMS with cylindrical pillars can enhance adhesion through elastic deformation, with a developed mechanical model matching experimental data and revealing how pattern geometry influences adhesion.

Contribution

It demonstrates that elastic deformation of micropatterned surfaces can significantly increase adhesion, and introduces a quantitative model linking pattern geometry to adhesion energy.

Findings

Elastic deformation enhances adhesion beyond interfacial area increase.

Adhesion saturation occurs when pillars are too close, due to elastic coupling.

A mechanical model accurately predicts adhesion based on pattern geometry.

Abstract

We present an investigation of the role of micropatterning on adhesion properties at soft deformable polydimethylsiloxane (PDMS)/ acrylic adhesive interfaces. Contrary to what has been observed for low aspect ratio rigid patterns, where the adhesion enhancement was found to only result from the increase of interfacial area due to patterning, we show that for soft elastic arrays of cylindrical pillars, the elastic deformation of the patterns can lead to noticeable extra adhesion increase. The effect of the geometrical characteristics of the patterning for hexagonal arrays of PDMS micropillars on the adhesion energy are presented. We show that varying the size of the pattern allows one to tune the adhesion energy, and that this adhesion enhancement saturates when the pillars become too close to each other, due a coupling of the elastic deformation fields inside the underlying substrate. A mechanical model has been developed and found in good quantitative agreement with experimental data, with as unique fitting parameter the rupture criteria for the adhesive on the top of the pillars. Such a rupture a rupture criteria can thus be extracted from systematic experiments on controlled patterned surfaces. This criteria remain sensitive to the chemistry of the surfaces.