APPLICABILITY OF TETRAPHENYLBORATE SALTS AS FREE-RADICAL INITIATORS

The reactivity of a series of triphenylbutylborate and tetraphenylbora te photoinitiators with various ammonium chromophores was studied. The relative initiator efficiency of the triphenylbutylborate salts as co mpared to the corresponding tetraphenylborate salts with a common chro mophore was determined: When the reduction potential of the chromophor e is near -1.3 V (vs SCE), tetraphenylborate salts become almost as ef ficient photoinitiators of free radical polymerization as the correspo nding triphenylbutylborate salts. A method to measure relative initiat or efficiency of salts with a common chromophore;based on fluorescent probe technology is proposed.