Investigating Photoinduced Reversible Solid‐to‐Liquid Transition in Azobenzene Liquid Crystal Copolymers

ABSTRACT In the photo‐responsive materials field, azobenzene liquid crystal polymers stand out because of their attractive properties such as photo‐responsive mechanical motion, surface hydrophobic/hydrophilic transitions, and phase changes. Current research on azobenzene liquid crystal polymers focuses primarily on synthesizing or characterizing structurally diverse homopolymers and selecting suitable molecular structures for photoinduced solid–liquid phase transitions. In this study, we synthesized and characterized a series of azobenzene‐acrylate copolymers incorporating varying levels of a liquid crystal monomer with no azobenzene. While the liquid crystal component broadened the copolymers' liquid crystal phase temperature range, it also altered their photoinduced liquefaction behavior. By combining experimental measurements with simulations, we examined how dipole moment changes during isomerization influence T g shifts. We found that copolymers with large dipole‐moment variations exhibit significant T g shifts—often resulting in photoinduced reversible solid‐to‐liquid transition—whereas those with minimal dipole changes fail to undergo phase transitions, even when their T g is near room temperature. These findings provide valuable guidance for designing azobenzene‐based photopolymers with customized phase transition properties for advanced applications.