Tunable Friction Through Microwrinkle Formation on a Reinforced Rubber Surface

Abstract

A new system is presented for controlling of friction through manipulating the contact between a rigid indenter and a porous-film-embedded polydimethylsiloxane (PDMS) rubber surface that can buckle to form regular microwrinkles depending on the applied lateral compression. The effect of this change in topography on friction is investigated with a fixed surface chemistry at the sliding interface to ensure a consistent value of adhesive shear strength per unit area of contact. With a wrinkled surface, a shorter stick–slip period and corresponding lower average force of friction are observed when compared to a flat PDMS surface. Based on the framework of Bowden–Tabor’s adhesive friction model, this result is attributed to a decrease in the contact area caused by an increase in the effective modulus and the distribution of interfacial contacts on the wrinkles. These results therefore imply that a shape-tunable microstructure is an effective approach to developing surfaces with dynamically tunable tribological properties.