Significant Adhesion Enhancement of Bioinspired Dry Adhesives by Simple Thermal Treatment

Abstract

Bioinspired dry adhesives with micropillar arrays can be harnessed for precise and environment-friendly manufacturing. This study presents a simple and robust approach for developing synthetic dry adhesives with significantly enhanced adhesion strength without sophisticated structural modification or chemical surface treatment. We show that when dry adhesives with micropillar arrays are annealed at slightly elevated temperatures of 150-200 degrees C, their adhesion strengths are remarkably enhanced (maximum normal adhesion: 50.0 N cm(-2)) compared to those that are not treated thermally (normal adhesion: 17.6 N cm(-2)). The enhanced adhesion levels obtained by simple annealing surpass those of previously reported dry adhesives having nanoscale hairs with high aspect ratios or mushroom-like pillars with large tips. Experimental investigations regarding the chemical structure, surface roughness, surface energy, and elastic modulus of the dry adhesive samples indicate that the enhanced adhesion originates from the annealing-induced enhancement of the adhesive's elastic modulus.