Phase Change Hydrogels for Bio‐Inspired Adhesion and Energy Exchange Applications

Abstract The adhesion strategies of the gecko's toe through surface adaptation of spatulas to increase contact area and the snail's epiphragm via dehydration‐induced solidification to lock interfaces are combined to design a class of adhesion‐switchable hydrogels. The hydrogels are made via incorporating CH 3 COONa·3H 2 O salt (SA) into polyacrylamide (PAM) aqueous networks to construct supersaturated and stimuli‐responsive phase change materials (PAM‐SA). The crystallization dramatically strengthens the mechanical properties, and tensile Young's moduli are 340.7 and 0.1 MPa for crystalline C‐PAM‐SA‐120% and soft PAM hydrogel. As a result, PAM‐SA‐120% shows excellent adhesive performance (adhesion strength, 348 kPa) compared with PAM hydrogel adhesive (adhesion strength, 7 kPa). The stimuli‐induced crystallization from H‐PAM‐SA‐120% phase change hydrogels releases thermal controllably, which can be utilized for thermochromic materials and thermotherapy.