Alignment Patterning of Polymer Main Chain by Spatiotemporal Photopolymerization: A Strategy for Improved Thermal Stability.

The precise alignment control of polymer main chains and liquid crystals (LCs) is effective for fabricating high-performance functional coatings. Conventionally, polymer chain alignment is regulated by mechanical stretching or flow fields; however, these approaches are inherently limited to one-dimensional alignment. Our recent discovery demonstrates that spatiotemporal photopolymerization using scanning light generates flow fields, a process termed scanning wave photopolymerization (SWaP). In this study, we explored the potential of SWaP for achieving precise microscale control over polymer main chain alignment. One-dimensional scanning of light induced uniaxial alignment of both polymer main chains and side-chain LC molecules. Thermal analysis of the resulting coating revealed that the high degree of polymer main-chain alignment in the coating recovered its original LC alignment upon cooling after thermal disordering, demonstrating excellent thermal stability. Furthermore, the most thermodynamically stable configuration of the polymer main chains depended on the LC phase. By designing the shape of the light, we successfully achieved two-dimensional alignment of polymer main chains at the microscale. This approach represents a foundational technology for the development of functional materials through molecular alignment control.