Reconfigurable Soft Actuators Constructed via Layer-by-layer Assembly

Stimuli-responsive actuators are candidates for the development of soft robots due to their shape deformation and environmental adaptation capabilities. Adaptation to environmental stimuli not only enables complex shape reprogramming but also benefits the recovery of mechanical injuries of the soft actuators. Nevertheless, reports on soft actuators that integrate shape-reprogramming and injury-healing functions into a monolithic actuating material through facile fabrication strategies remain scarce. Herein, a stimuli-responsive and healable actuator is developed via layer-by-layer casting of two stimuli-responsive materials with complementary properties. Upon specific stimulation, these two materials reorganize their structural network at the nano- and microscales and heal. The resulting actuator exhibits a robust photo-responsive actuating strength due to the asymmetric volumetric responses of the two layers. Importantly, the whole actuator can be healed with the aid of a sequential heating-humidifying–drying treatment, achieving excellent healing efficiency in both mechanical strength (72%) and actuating strength (95%). Moreover, the initial actuation modes can be restored and diversified through humidifying or heating-assisted welding procedures, respectively. This work demonstrates a facile strategy to construct reprogrammable actuators with healing and welding abilities stimulated by two environmental stimuli and provides a platform for developing adaptable materials to a changing environment.