Interfacial Reinitiation of Free Radicals Enables the Regeneration of Broken Polymeric Hydrogel Actuators

Living organisms,from plants to animals,have inspired and guided the design and fabrication of polymeric hydrogels with biomimetic morphology,shape deformation,and actuation behavior.However,the existing polymeric hydrogels are fragile and vulnerable,which seriously hinders further application.Therefore,endowing hydrogels with a biomimetic self-growth property and regenerating the macroscopic shape of hydrogels after they suffer significant damage are highly desirable for the next generation of adaptive biomimetic hydrogels.Inspired by the tail regeneration of geckos,we herein report an efficient and universal strategy of interfacial diffusion polymerization(IDP),which can regenerate the polymeric layer at a solid–liquid interface,thereby growing new hydrogels on the existing hydrogel layers.Through changing the solvent viscosity and/or monomer type of the hydrogel precursor,diverse new hydrogels have been regenerated to endow the initial hydrogels with additional fluorescent functions and/or actuating properties.Due to the high efficiency and universality of IDP,an injured hydrogel actuator can be repaired,regenerated,and recovered to its initial condition,even after suffering severe damage such as cutting or piercing.We believe that the regeneration strategy of polymeric hydrogels will inspire the design of biomimetic materials and motivate the fabrication of the next generation of soft robots with adaptive and multifunctional properties.