Advancing smart dry adhesives with shape memory polymers
Changhong Linghu, Tong Mu, Wei Zhao, Yangchengyi Liu, K. Jimmy Hsia, Jinsong Leng, Huajian Gao
Abstract
Smart dry adhesives, a rapidly growing class of intelligent materials and structures, are engineered to provide strong, robust adhesion when needed while also allowing for controlled, easy detachment in response to specific stimuli. Traditional smart adhesives, often exemplified by fibrillar structures made of elastomers, face a number of challenges. These include limitations on maximum adhesion strength imposed by microstructural dimensions, restricted adaptability to surfaces with varying degrees of roughness, and an inherent trade-off between adhesion strength and switchability. This review explores how shape memory polymers (SMPs) can address these challenges and, through their rubber-to-glass (R2G) transition capability, provide a powerful foundation for the next generation of smart dry adhesives. Specifically, we summarize and elucidate the mechanisms by which SMPs enhance adhesion strength and switchability through material characteristics such as tunable stiffness, shape-locking, and shape-memory effects. Additionally, we discuss a wide range of innovative designs and applications of SMP adhesives, offering insights into the ongoing challenges and emerging opportunities in this rapidly evolving field.