PEDOT:PSS Coating Improves Gecko-Inspired Adhesive Performance

Abstract

We report a surface treatment for an elastomeric dry adhesive that improves adhesion, especially on surfaces with microscopic roughness. The process involves coating wedge-shaped polydimethylsiloxane (PDMS) features of the adhesive with a 50 nm coating of poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). As compared to the uncoated adhesive, performance is 1.25× better on smooth surfaces like glass, with a maximum shear stress of 70 kPa in shear and 25 kPa in normal adhesion under controlled loading conditions. On slightly rough surfaces such as paper and panels painted with flat paint, it provides between 2.5× and over 12× greater shear stress than the uncoated adhesive. Moreover, the coating, being much stiffer than the underlying wedges, does not increase the tendency to become dirty and does not tend to self-stick, or clump. Durability tests show that the performance remains substantially unchanged for 80,000 attachment/loading/detachment cycles. We describe the coating process, present the test results, and discuss the reasons for the enhanced performance on a variety of materials.