Bifunctional co-initiators: A new strategy for the design of efficient systems in radical photopolymerization reactions under air

Bifunctional co-initiators containing amine and silane groups (silylamines) are proposed for radical photopolymerization in experimental conditions (e.g. low light intensity, low viscosity thin samples, UV and visible light exposure) where a strong deleterious oxygen effect occurs. In the presence of benzophenone, isopropylthioxanthone, camphorquinone, 2,6-diphenyl-4-(4′-dimethylaminophenyl) thiopyrylium tetrafluoroborate, chloro-HABI and cleavable photoinitiators, these compounds show a high reactivity under air, even better than that observed for a reference amine as a hydrogen donor. The associated mechanisms are investigated by laser flash photolysis (LFP) and Kinetic ESR.