Capsanthin-iodonium salt system for free radical photopolymerization under LED irradiation

The current photoinitiator (PI) is effective under mercury lamps but exhibits limited selectivity towards different radiation sources, which hinders its compatibility with eco-friendly LED lighting and raises concerns about toxicity and deep coloration. Capsanthin (Cap), with its strong photo-absorption in the 400–500 nm range, utilizes its conjugated structure to align the PI's absorption wavelength with the LED's emission spectrum . This study introduced Cap as a natural photosensitizer (PS) for free radical photopolymerization under LED irradiation. The Cap-based initiation system demonstrated promising photoinitiating capabilities under a 405 nm LED , achieving over 50 % double bond conversion in polymerized monomers . Furthermore, the system's photobleaching properties were exceptional, and its cytotoxicity was significantly lower than that of traditional PIs, such as benzoin methyl ether. The Cap's photochemical behavior under LED irradiation was explored, investigating its photoinitiating capacity and mechanism through fluorescence, photolysis, and electron paramagnetic resonance techniques. This research is vital for developing bio-based photoinitiating systems for photopolymerization in LED light environments.