Reversibly and Irreversibly Humidity‐Responsive Motion of Liquid Crystalline Network Gated by SO2 Gas

Manipulating functional liquid crystalline networks (LCNs) by multiple stimuli has been a hot topic in the research of smart actuators and fabrication of biomimetic robots. Here, a single‐layer LCN film showing dual responsiveness to humidity and SO₂ gas is prepared. Interestingly, the humidity sensitivity of the LCN film can be gated by exposing the film to SO₂. At the same time, the SO₂ sensitivity is strongly affected by the ambient relative humidity (RH) and the response time is able to be tuned by changing the RH over a wide range. The mechanism of this dual response of the LCN film is ascribed to the neutralization of carboxylic acid and in situ acidification of the carboxylic salt. The reversibly and irreversibly humidity‐induced motion gated by SO₂ renders the LCN film valuable in the design and preparation of multifunctional devices.