Dyes based on a 1,4-naphthoquinone skeleton as new type Ⅱ photoinitiators for radical polymerisation

摘要

Photoredox pairs consisting of 1,4-naphthoquinone dyes and commercially available hydrogen donors (2-mercaptobenzoxazole, 2-mercaptobenzothiazole, 2-mercaptobenzimidazole and 2,5-dimercapto-1,3, 4-thiadiazole) are found to be effective initiator systems for the radical polymerisation of trimethylolpropane triacrylate under visible light. The efficiency of these initiator systems is discussed in terms of the free energy change for the electron transfer process from the dye to the hydrogen donor. The results show that the photoinitiation ability of tested photoredox pairs depends on the structure of both the dye and the hydrogen donor.