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

The photochemistry of five new substituted benzoı̈n ethers has been investigated 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: three of them present a very interesting initiation efficiency for the polymerization of acrylates; photolysis leads to a cleavage reaction resulting from a very short triplet state and is followed by subsequent cleavage. The other two, which exhibit a better near UV–Vis light absorption, have very poor efficiencies as photoinitiators since they are very stable under irradiation. Full diagrams of excited state processes are discussed.