Conjugated Poly(ionic liquid)‐Based Nanoporous Membrane for Rapid Moisture Response

Stimuli‐responsive nanoporous materials represent a newly emerging category of functional materials, for which instant and significant response behavior is strongly demanded but still challenging. Herein, a new kind of conjugated poly(ionic liquid)s (PILs) synthesized via a simple one‐pot spontaneous nucleophilic substitution and polymerization between 4,4'‐vinylenedipyridine and propargyl bromide is reported. A nanoporous membrane actuator is further developed via ionic complexation between the current PIL and trimesic acid. The actuator carries a gradient density in the hydrophobicity content along the membrane cross‐section, which results in a fast response to moisture. Conjugated poly(ionic liquid)s with a polyacetylene backbone is synthesized simply by mixing 4,4'‐vinylenedipyridine and propargyl bromide under mild conditions. The as‐prepared polymer A‐TFSI exhibits reversible solid‐to‐gel conversion with an increase in temperature. Furthermore, the A‐TFSI‐based nanoporous membrane exhibits a fast response to moisture and large‐scale displacement, which shows great capability for biomimetic movements and interfacing with biological environments.