Controlled Synthesis of Liquid-Crystalline Polymers Under Ambient Conditions by Red-Light-Driven ATRP

Red-light-driven atom transfer radical polymerization (ATRP) using methylene blue as a photocatalyst has attracted considerable attention due to its high efficiency and oxygen tolerance. However, its application to functional polymers remains unexplored. Here we demonstrate the synthesis of liquid-crystalline polymers (LCPs) under ambient conditions using red-light-driven ATRP. Well-controlled polymerizations with high monomer conversions were achieved within several hours. The polymer growth could be precisely regulated by alternating the light irradiation on and off. Molecular weights were tuned by adjusting the polymerization conditions, affording LCPs with narrow molecular weight distributions. A clear relationship between molecular weight and LC behavior was observed. The method was extended to various mesogenic monomers and polymerizable groups, confirming its broad applicability. Moreover, controlled polymerization was achieved using accessible light sources such as sunlight and smartphone LED flashlights. This versatile approach enables efficient LCP synthesis and facilitates exploration of structure-property relationships in functional soft materials.