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

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 CH3COONa center dot 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.

Automated summary

A class of adhesion-switchable hydrogels is designed by combining the adhesion strategies of the gecko's toe and the snail's epiphragm. The hydrogels, made of CH3COONa·3H2O salt incorporated into polyacrylamide aqueous networks, exhibit excellent adhesive performance and mechanical properties due to crystallization. The stimuli-induced crystallization from these hydrogels can release heat controllably, making them suitable for thermochromic materials and thermotherapy.