Large-molecular-weight acyldiphenylphosphine oxides as low-mobility type I photoinitiator for radical polymerization

In recent years, the light source for photopolymerization technology is evolving from energy-hungry mercury lamps to the safer light-emitting diodes (LEDs), and it is urgent to develop new photoinitiator adapted to the photopolymerization system with LED light source. Some acyldiphenylphosphine oxide photoinitiators have been designed and developed for LED light source, but their application is severely limited in the fields of food packing, medical equipment, environmentally-friendly product etc. due to their high mobility in photocured polymers. In this study, eight acyldiphenylphosphine oxide molecules (DAPO-1 ∼ DAPO-8) were synthesized by introducing large molecular weight groups and their UV–visible absorption, photodegradation quantum yield, photopolymerization properties, mobility and solubility in monomer were determined. Thereinto, photoinitiators show lower mobility than TPO, the photoinitiator commonly used in industry, as well as good solubility in monomers and excellent photopolymerization performance. Therefore, they can serve as potential substitutes for commercial TPO, especially in the application of low-migration photocurable system.