Photopatterning-Induced Diffusion for Directed Molecular Alignment

Photopolymerization has been emerged as a pivotal technique for spatially controlled solidification of polymer networks, owing to its compatibility with diverse patterning methods such as photomask lithography and digital light projection. While spatial confinement of polymerization enables the fabrication of microscale structures, it inherently induces concentration gradients of unreacted monomers between exposed and unexposed regions, leading to inevitable diffusion phenomena. This diffusion not only causes swelling of the polymer network and blurring of patterned edges but also acts as a driving force for the formation of novel microstructures. When combined with liquid crystalline phases, which exhibit collective molecular behavior and are highly responsive to shear-induced alignment, the interplay between polymerization kinetics and diffusion enables simultaneous control over both structure and internal anisotropy. This review summarizes recent advances in understanding the coupled kinetics of photopolymerization and diffusion during photopatterning and highlights emerging strategies for directing microstructural morphology and internal alignment. These insights offer new perspectives for designing hierarchical materials with programmable architecture and functionality.