Photomechanical Effects in Liquid‐Crystalline Polymer Networks and Elastomers

This chapter focuses on the preparation of photoresponsive liquid-crystalline networks and elastomers and the mechanical responses they exhibit. It also focuses on the specific nuances of the liquid-crystalline materials, and discusses the semantics used to describe them and the general synthetic methods by which they are prepared. Some groups focused on synthetic methods to prepare both glassy and elastomer liquid crystal networks with free-radical or cationic polymerization starting from low-molar-mass liquid-crystalline precursors. By far the most common method to prepare liquid-crystalline polymer networks is and has been the free-radical polymerization of (meth)acrylate liquid-crystalline monomers (sometimes called reactive mesogens). By employing the basic principles introduced hereto, azobenzene-functionalized liquid-crystalline polymer networks and elastomers have been shown to generate a number of remarkable photomechanical outputs. The chapter further reviews the synthesis and characterization of photomechanical responses observed in materials prepared with hydrosilylation chemistry as well as poly(meth)acrylates.