A reactive azobenzene liquid-crystalline block copolymer as a promising material for practical application of light-driven soft actuators

Abstract

Cross-linked liquid-crystalline polymers containing azobenzene have been drawing great research interest of scientists due to their significant values in the design of light-driven soft actuators. However, poor processabilities due to the chemical cross-linking severely prevent their practical applications. Here, we designed and synthesized a novel reactive block copolymer PEO-b-PAZO bearing N-hydroxysuccinimide carboxylate substituted azobenzene groups. This copolymer is compatible with the traditional polymer processing methodology including melt and solution processing methods, providing a facile way to prepare the photoresponsive films and fibers, and enabling post-crosslinking after processing through a mild reaction between N-hydroxysuccinimide carboxylate substituents and a difunctional amine. Most importantly, the prepared fibers and films showed reversible photodeformation regulated by alternating irradiation of UV and visible light (365 nm/470 nm). We envision that this novel liquid crystalline polymer will open up new possibilities for low-cost fabrication of high performance photo-driven actuators on a large scale.