Octopus-Inspired Smart Adhesive with Adjustable Stiffness for Adhesion on Uneven Surfaces in Air and Underwater

Octopus-inspired smart adhesives have exhibited remarkable application prospects in domains including soft grippers and medical monitoring. Nonetheless, existing bioinspired adhesives still exhibit a notable gap in adhesion strength compared to living tissues due to the uncontrollable stiffness, especially when adhering to uneven surfaces. In this study, shape memory polymer (SMP) is utilized with photothermal conversion properties to mimic the characteristics of octopus tentacle suckers and muscles, proposing a photoresponsive smart adhesive (PSA) with adjustable stiffness. Leveraging the shape memory performance of the SMP, this smart adhesive is capable of regulating its own stiffness to achieve conformal contact, shape locking, and active release. Moreover, owing to its hydrophobic property, this smart adhesive is not only suitable for manipulating surfaces with various features in air but also capable of functioning effectively in underwater environments. The adhesive proposed in this paper can achieve solid adhesion strengths ≈18-fold and 11-fold higher than traditional octopus-inspired adhesives in air and underwater environments, respectively, further enhancing the attachment and detachment functions. It holds great application potential in industrial production lines and daily life, opening up a brand-new direction for the development of adhesive materials.