Pressure tunable adhesion of rough elastomers

The ability to control adhesion is critical in various technologies including wearable electronics, pressure sensitive adhesives, and robotic systems. Biomimetic fibrillar structures, random surface roughness, and chemical surface treatments have been employed to modify the adhesion energy of materials used in these applications. However, polymer thin film dewetting has not been investigated as a surface modification tool to control adhesion. In this work, polystyrene thin films are thermally annealed on a polydimethylsiloxane substrate, causing them to dewet and form stiff, microscopic asperities on the soft substrate. The size of the asperities increases with increasing pre-annealing film thickness. Adhesion is quantified by flat-punch normal indentation testing. The largest asperities exhibited a decrease in adhesion to below the sensitivity of the instrument. More interestingly, the surfaces covered with the smallest asperities displayed a pressure-dependent adhesive response. By increasing the normal compressive stress applied prior to separation, the total debonding energy increased monotonically on the smallest asperity-covered surfaces.

Automated summary

The ability to control adhesion is crucial in various technologies, and this study investigates using polymer thin film dewetting as a surface modification tool. The research finds that by thermally annealing polystyrene thin films on a polydimethylsiloxane substrate, microscopic asperities can be formed, affecting adhesion properties. The study also reveals a pressure-dependent adhesive response on surfaces covered with the smallest asperities.