Structures/properties relationships in photoinitiators of polymerization XI. Behavior of new benzylbenzoin benzyl ethers

The photochemistry of five new substituted benzoin ethers has been investig ated and their polymerization activities evaluated; the cleavage mechanisms have been explored using steady-state photolysis and mass spectroscopy and the excited state processes studied with time-resolved laser spectroscopy. The five compounds can be separated into two groups: thrice of them presen t a very interesting initiation efficiency for the polymerization of acryla tes; photolysis leads to a cleavage reaction resulting from a very short tr iplet state and is followed by subsequent cleavage. The other two, which ex hibit a better near UV-Vis light absorption, have very poor efficiencies as photoinitiators since they are very stable under irradiation. Full diagram s of excited state processes are discussed. (C) 2000 Elsevier Science Ltd. All rights reserved.