Molecular Hydrophilicity-Accelerated Shape Memory Hydrogels with Integrated Sensing Performance

With the capacity to store and release elastic energy, shape memory hydrogels are promising candidates to construct artificial muscles but usually suffer from low power density due to the slow contraction process and lack real-time sensing function. Inspired by the collaboration of biological muscles and neural systems in nature, we developed poly(acrylic acid- co -acrylamide)/calcium acetate (P(AA- co -AM)/CaAc) shape memory hydrogel with improved actuating speed and integrated sensing performance. The shape memory hydrogel undergoes phase separation at elevated temperatures and stores the elastic energy, generating movement at low temperatures, and releases the stored energy. The energy releasing process could be accelerated by introducing hydrophilic amide groups into the polymer network, thereby improving the power density of the hydrogel based artificial muscles. Moreover, the shape memory hydrogel exhibits excellent conductive performance with a stable output signal and fast responsiveness, enabling the integration of actuating and real-time sensory performance. This strategy could inspire the design and fabrication of intelligent actuating materials and expand their applications in artificial muscles and soft robots.