Photoinduced Exfoliation of a Polymeric N‐Benzylideneaniline Liquid‐Crystalline Composite Based on a Photoisomerization‐Triggered Phase Transition

Hydrogen‐bonded liquid crystalline polymer composites containing N‐benzylideneaniline (NBA) as a photoresponsive mesogenic unit are prepared. The mesomorphic properties of the composite decrease upon exposure to UV light because of trans‐to‐cis photoisomerization, which affects the adhesive properties and allows facile exfoliation. In addition, the destabilized phase spontaneously reverts to the initial state when UV light irradiation stops. After exfoliation, the composite can be rebonded to a glass substrate by heating above its melting point. This is the first observation of the phase transition of an NBA liquid crystalline polymer. An isothermal phase transition from a liquid‐crystalline phase to an isotropic phase in response to UV irradiation in a hydrogen‐bonded polymeric N‐benzylideneaniline (NBA) composite, as well as in polymeric NBA, is demonstrated. The hydrogen‐bonded composite can bond glass substrates and support a suspended weight of 106 times their own weight. Furthermore, the adhesive force is reduced on irradiation with UV light.