Thermally switchable adhesions of polystyrene-block-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 degrees 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 degrees C may guide the design of bio-inspired artificial analogues, which could approach gecko's climbing behavior. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4754135]