Smart adhesives with switchable adhesion have attracted
considerable
attention for their potential applications in sensors, soft grippers,
and robots. In particular, surfaces with controlled adhesion to both
solids and liquids have received more attention, because of their
wider range of applications. However, surfaces that exhibit controllable
adhesion to both solids and liquids often cannot provide sufficient
adhesion strength for strong solid adhesion. To overcome this limitation,
this study developed a triple-bioinspired shape memory smart adhesive,
drawing inspiration from the adhesion structures found in octopus
suckers, lotus leaves, and creepers. Our adhesive design incorporates
microcavities formed by a shape memory polymer (SMP), which can transition
between rubbery and glassy states in response to temperature changes.
By leveraging the shape memory effect and the rubber–glass
(R-G) phase transition of the SMP, the adhesion of the surface to
smooth solids, rough solids, and water droplets could be switched
by adjusting the temperature and applied force. Notably, the adhesives
designed herein exhibited high adhesion strength (up to 420 kPa) on
solids, facilitated by the shape interlocking effect and the negative
pressure generated within the microcavities. Furthermore, the programmable
transport of solids and liquids can be achieved by utilizing this
switchable adhesion. This approach expands the possibilities for designing
smart adhesives and holds potential for various applications in different
fields.