Liquid Crystal Polymer Networks and Elastomers for Light-Fueled Robotics

Summary Liquid crystal (LC) polymer networks and elastomers are synthetic cross-linked polymer systems constituting liquid crystalline building blocks, or mesogens. This chapter provides an up-to-date overview of light- fueled LC network (LCN) robotics. It explains photoactuation and light robotics, and discusses the basic physics that a small-scale LCN robot encounters, as the forces at the microscale are very different from common everyday experience. The chapter also introduces the photoactuation mechanisms, making a comparison between photothermal and photochemical actuation strategies, which often times yield distinct actuation behavior and shape changes. Azobenzene-based photochemical actuators often times exhibit photoinduced bending as opposed to in-plane photocontraction. The chapter considers autonomous actuation, driven by dynamic light-response in the material, to adopt a significant role in the design of future LCN robots. Uniaxially aligned LCNs can undergo reversible contraction-expansion along the molecular director axis, thus presenting muscle-like motion under external stimulus.