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Ketocoumarins as photosensitizers and photoinitiators
Author(s) -
Williams J. L. R.,
Specht D. P.,
Farid S.
Publication year - 1983
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760231809
Subject(s) - benzophenone , polymerization , photochemistry , photoinitiator , amine gas treating , acetic acid , ketone , polymer , pyridinium , alkoxy group , chemistry , redox , polymer chemistry , materials science , organic chemistry , alkyl , monomer
Several 3‐ketocoumarins with alkoxy or dialkylamino substituents in the 7 position, which are efficient sensitizers for crosslinkable polymers, were evaluated as photoinitiators. Proper combinations of certain derivatives of these ketocoumarins with activators such as amines, acetic acid derivatives, and alkoxypyridinium salts gave quantum yields for initiated radical polymerization much higher than that obtained from the Michler's ketone/benzophenone combinations. For each class of activators the dependence of the efficiency of polymerization on the redox properties of the ketocoumarins is explained in terms of charge transfer or electron transfer from the activator to the excited ketocoumarin (acetic acid and amine activators, respectively) or electron transfer in the opposite direction (pyridinium salt activators).