Chemically and biochemically responsive liquid crystal polymer networks and elastomers

Chemically responsive liquid crystal (LC) based polymers can change their mechanical or optical properties when exposed to chemical triggers. The anisotropy inherent in LC materials allows the programming and control of predictable changes in shape, stiffness, and/or color. By further incorporating ionizable moieties into the polymer formulation, these materials may exhibit a response to chemical stimuli such as pH, solvents, or specific analytes. This mini-review highlights seminal papers and recent advances in the use of chemoresponsive LC polymers for sensing and actuation. We also discuss how these materials can respond to biochemical stimuli through the immobilization of enzymes into the network, and provide examples of different types of responses (e.g., shape reconfigurations and color transitions). Multiple ways of modulating the response, such as chemical gating and enzyme patterning, are also reviewed. Finally, we illuminate some of the challenges and opportunities in the use of these materials for state-of-the-art applications, including shape-controllable medical implants and real-time field-deployable sensors. & COPY; 2023 Society of Industrial Chemistry.