Structure/properties relationships in photoinitiators of polymerization: 12. A novel bifunctional compound

A novel bifunctional photoinitiator BP-SK based on ketosulfone–benzophenone moieties is presented. At a given amount of compound, BP-SK is 20% to 40% more active than dimethoxy phenylacetophenone for the photocuring of multiacrylates in bulk under air. The triplet state of this compound undergoes a β cleavage reaction at the ketosulfone moiety and generates a ketyl radical upon addition of an amine. The quantum yield of intersystem crossing is 0.7 in acetonitrile; the triplet energy level is located around 275 kJ mol−1. The whole results shows the characteristics of the photopolymerization reactions as well as the processes occurring in the excited states.