"Shape-Changing Liquid Crystal Polymer Networks"
Liquid crystalline networks (LCNs) are versatile functional materials because of the unique properties of liquid crystalline molecules, e.g., self-organization, reversible phase transition, and macroscopic orientation under external fields. The coupling between LC molecules and polymer networks allows these remarkable properties to be transferred to the bulk material and has resulted in a number of functional LCNs that are thermally-responsive and can change their shape reversibly due to the reversible LC phase transition upon temperature cycling. In this lecture, we show how the incorporation of photo-responsive chromophores into LCNs allows the material to convert light energy into mechanical work because of the transformation between two geometrically different isomers upon light irradiation. We demonstrate a simple route to incorporate three functional building blocks, including chromophores, liquid crystals, and dynamic covalent bonds, together into a liquid crystalline network. The three functionalities show good compatibility and the resulting material can exhibit various photomechanical responses, dual-stimuli induced shape memory and self-healing properties, and excellent processability and recyclability.