Novel chalcone-based phenothiazine derivative photoinitiators for visible light induced photopolymerization with photobleaching and good biocompatibility

Abstract

Two novel visible light photoinitiators 4-(10-methyl-10H-phenothiazin-3-yl) but-3-en-2-one (PBO) and (1E,4E)-1,5-bis(10-methyl-10H-phenothiazin-3-yl)-1,4-pentadien-3-one (BMPPO) were successfully designed and synthesized. PBO and BMPPO have broad absorption range from 350 to 500 nm with the maximum absorption wavelength at 400 nm and 440 nm respectively. Three-component photoinitiating system of BMPPO/iodonium/amine was developed for free radical polymerization of acrylates. The results demonstrated that the photoinitiating system displayed rapid polymerization and high final vinyl group conversions under the irradiation of UV-LED (365 nm), blue LED (440) nm and solar light resource. Moreover, photopolymerization kinetics was studied by real-time FT-IR spectrum, the double band conversion was achieved up to 90% for BMPPO. The photocuring mechanism was identified via steady state photolysis and electron spin resonance spin-trapping experiments. The possible photoinduced mechanism of PBO and BMPPO in the presence of a co-initiator occurred through electron transfer. In addition, BMPPO possesses rapid photobleaching and good biocompatibility performance tested by photoinduced degradation and cytotoxicity experiments respectively, which exhibited that BMPPO has potential for light-color coatings and food packaging field.