Thermally switchable adhesions of polystyrene-b lock-poly(n-isopropylacrylamide) copolymer pillar array mimicking climb attitude of geckos

Abstract

Inspired by the gecko foot pad, we fabricated polystyrene-block-poly(N-isopropylacrylamide) (PS-b-PNIPAAm) copolymer pillar array to mimic climbing attitude of a gecko, alternately attach to and detach from a surface. The pillar array structure of the PS segment significantly enhances both of the hydrophilic and hydrophobic property of PNIPAAm segment tips at 25 and 50 °C, respectively, which could generate alternating adhesive forces of approximately 120 and 11 nN. The dramatic change in adhesive and friction force difference at 25 and 50 °C may guide the design of bio-inspired artificial analogues, which could approach gecko's climbing behavior.