Newly Synthesized Chromophore-linked Iodonium Salts as Photoinitiators of Free Radical Photopolymerization

Iodonium salts are the topic of interest in the field of photopolymerization as they act as effective photoinitiators and generators of photoacid. Yet, the current commercially available iodonium salts have low absorption above 300 nm whereby limiting the use of the long-wavelength of light irradiations to trigger polymerization. Iodonium salts are thus generally used in couples with photosensitizers (e.g., dyes) to extend the usage under irradiation of red-shifted light wavelength. In this research, the synthesis of chromophore-linked (anthraquinone-based and flavone-based chromophores) iodonium salts is present. They can initiate free radical polymerization with 320–480 nm irradiation and show much better photoinitiation ability as compared to commercial iodonium salts, especially when they act as mono-component photoinitiators. Steady-state photolysis and electron spin resonance spin trapping experiments are also carried out to evaluate the relevant photochemical mechanism.