Manipulation of photoresponsive liquid-crystalline polymers and their applications: from nanoscale to macroscale

As a smart material, photoresponsive liquid-crystalline polymers exhibit interestingly tunable properties from the nanoscale to the macroscale, which are attributed to their combination of liquid crystal ordering and photoswitchable features. An azobenzene-containing liquid-crystalline polymer is a typical representative, which has been studied from many different aspects. However, the lack of research on the structure-performance relationship and multi-scale manipulation has limited its applications in a broader field. Over the past few years, great efforts have been devoted to achieving the control at multiple scales using light, which has promoted their applications in the fields of energy storage, advanced anticounterfeiting and switchable adhesion. Here, we summarize recent progress in photoresponsive liquid-crystalline polymers, including molecular design, fabrication techniques and the manipulation mechanism from the nanoscale to the micrometre scale and then the macroscale. Their various applications based on abundant photoresponsive properties are systematically summarized. Finally, the existing challenges and opportunities in this field are discussed. We summarize the molecular design of photoresponsive liquid-crystalline polymers, manipulation at multiple scales and various applications based on their intrinsic properties, providing an opportunity for future development in this field.