Photoresponsive Polymer Films with Directly Micropatternable Surfaces Based on the Change in Free Volume by Photo‐Crosslinking

Abstract Photoresponsive polymers, whose structures or properties change when exposed to ultraviolet (UV) light, have been studied for the fabrication of micro‐ and nano‐devices for various applications. Herein, photoresponsive polymer films are investigated with directly micropatternable surfaces formed by only UV exposure without the development process using solvents. The photoresponsive polymer films are designed based on the decrease in free volume induced by the photodimerization of cinnamoyl groups. The photoresponsive polymers are synthesized by copolymerizing a monomer with photodimerizable groups and a poly(dimethylsiloxane) macromonomer. Micropatterns are easily formed on the film surfaces by only UV exposure using photomasks. The micropatterns are achieved due to the decrease in the film thickness with a decrease in the free volume induced by photo‐crosslinking. Using a decrease in free volume by photo‐crosslinking leads to wide practical applications with simple processes and low costs.