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 multia crylates in bulk under air. The triplet state of this compound undergoes a beta cleavage reaction at the ketosulfone moiety and generates a ketyl radi cal 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 photopolymerizatio n reactions as well as the processes occurring in the excited slates. (C) 2 001 Elsevier Science Ltd. All rights reserved.