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Regarding the global energy crisis, it is of profound significance to develop spontaneous power generators that harvest natural energy. Fabricating humidity‐responsive actuators that can conduct such energy transduction is of paramount importance. Herein, we incorporate covalent organic frameworks with flexible polyethylene glycol to fabricate rigid‐flexible coupled membrane actuators. This strategy significantly improves the mechanical properties and humidity‐responsive performance of the actuators, meanwhile, the existence of ordered structures enables us to unveil the actuation mechanism. These high‐performance actuators can achieve various actuation applications and exhibit interesting self‐oscillation behavior above a water surface. Finally, after being coupled with a piezoelectric film, the bilayer device can spontaneously output electricity over 2 days. This work paves a new avenue to fabricate rigid‐flexible coupled actuators for self‐sustained energy transduction. [ABSTRACT FROM AUTHOR]

Fabricating mechanically responsive actuators that can efficiently convert external stimuli into mechanical work is of great significance for real‐world applications. Herein, we rationally design a class of rigid–flexible coupling crystalline crosslinked polymers (CCPs) to fabricate vapomechanically responsive actuators. Interfacial condensation reactions of flexible macromers with rigid monomers afford a series of freestanding CCP membranes. Notably, it is the first example where crosslinked polymers show high crystallinity and porosity. Moreover, the CCP membranes exhibit good mechanical properties and interesting vapor‐triggered actuation performance, which is reversible and repeatable. We find that the unusual polymer structures, high vapor sorption, and anisotropic membranes contribute to the directional deformation performance of the CCP actuators. The synthesis approach in this work provides new insights into the design and fabrication of smart materials for advanced applications. [ABSTRACT FROM AUTHOR]