Laser Flash Photolysis in High- Speed Photopolymer Coating Layers: Elucidation of Radical Generated from Coumarin Dye Sensitized Photo- initiator Systems

Abstract

Radical generation from photoinitiation systems containing carbonylbiscoumarin dye with a radical-generating reagent, 3,3′-carbonylbis[7-(diethylamino)-2H-l-benzopyran-2-one](KCD-DA), with 2,2′-bis(2-chlorophenyl)-4,4′,5,5′-tetraphenyl-1,1′- bi- 1H- imidazole (BI) in a poly(methyl methacrylate) (PMMA) film have been investigated by laser flash photolysis using a total reflection cell. Imidazolyl radical(Im ·) was predominantly generated from carbonylbiscoumarin triplet sensitized decomposition of BI, the quantum yield, φ 0 1 m · of Im · at an infinite concentration of BI was measured, φ 0 1 m · =0. 5 ∼ 1.4. The high quantum yield, φ 0 1 m · implies an efficient KCD- DA triplet sensitized photoinitiation system containing BI.