Recent advances in photoresponsive liquid-crystalline polymers containing azobenzene chromophores

Abstract

Famous for their photoisomerization, azobenzene and its derivatives have been intensively studied as among the most fascinating advanced materials. In particular, azobenzene-containing liquid-crystalline polymer (LCP) materials show unique properties by combining the self-assembly of liquid crystals and photoresponsive performance of chromophores. Here, we highlight their intriguing properties and potential applications from photonics to photodriven motion as well as the novel nanotechnology. The photoresponsive features such as photochemical phase transition, photoinduced alignment and photo-triggered cooperative motion often result in a large modulation of the refractive index, which can be easily fixed in LCP films. This is very advantageous for their photonic applications. Upon forming connections by three-dimensional crosslinking, a large deformation can be photoinduced from the micro to the macro scale, enabling applications as photomechanical and photomobile materials to be found. Upon integrating with the microphase separation of well-defined block copolymers, they exhibit photocontrollable regular nanostructures on the macroscopic scale with excellent reproducibility and mass production, meaning they can be used as nanotemplates for nanoengineering and nanofabrication.