A super large and robust free-standing organic cage membrane used for ultrasensitive solvent actuator

A robust free-standing organic cage membrane has been developed through a simple one-step solution-processing method of evaporation, which is fabricated by pure organic molecular cages and used without the addition of underlying support or polymer matrix. In addition, the organic cage membrane shows good mechanical stability, out-standing flexibility and self-healing performance. After 1,000,000 cycle bending tests, its mechanical properties are retentive, which provides the possibility of preparation of large dimension cage membranes (20 cm × 20 cm) and their derivatives in a simple way and hence shows promise in technical applications in separation, catalysis, and energy in the future. Then, a gradient structure is introduced into the membrane by quaternization reaction between the tertiary amine on the organic cages and methyl iodide. Thus, the membrane shows ultrasensitive gas and solvent stimuli responsive performance, which possesses the potential of monitoring the low portion of chloroform stimulus (0.61 mol%). [Display omitted] •A super large (20 cm × 20 cm), robust and free-standing organic cage membrane has been developed.•Its mechanical properties can be nearly retentive after 1,000,000 cycle bending tests or self-healing process within 3 s.•A biomimetic gradient actuator based on the membrane has been fabricated.