CIHIDECAR   12529
CENTRO DE INVESTIGACIONES EN HIDRATOS DE CARBONO
Unidad Ejecutora - UE
artículos
Título:
PYRROMETHENE DERIVATIVES IN THREE-COMPONENT PHOTOINITIATING SYSTEMS FOR FREE RADICAL PHOTOPOLYMERIZATION
Autor/es:
O. I. TARZI; X. ALLONAS; C. LEY; J-P. FOUASSIER
Revista:
JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY
Editorial:
JOHN WILEY & SONS INC
Referencias:
Año: 2010 vol. 48 p. 2594 - 2603
ISSN:
0887-624X
Resumen:
1,3,5,7,8-pentamethyl pyrromethene difluoroborate complex (HMP) and 2,6-diethyl-8-
phenyl-1,3,5,7-tetramethylpyrromethene difluoroborate complex (EPP) were used to initiate
the polymerization of a diacrylate in a two- and a three-component photoinitiating system,
together with an amine (ethyl-4-dimethylaminobenzoate, EDB) and triazine A (2-(4-
methoxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine, TA) as coinitiators. For both
pyrromethene dyes, the highest conversion was achieved with the three-component
photoinitiating system. As these dyes have high fluorescence quantum yields, steady state and
time-resolved techniques were used to study the possible fluorescence quenching by the
amine and the triazine, as well as laser flash photolysis to investigate the electron transfer
process that occurs in these photoinitiating systems from either the singlet or triplet excited
states. The electron transfer reaction is evidenced by using time-resolved photoconductivity.
Experiments show that the main interaction between the dye and both coinitiators is through
its excited singlet state and the process is more efficient when TA is present. The beneficial
effect noted when both coinitiators are used in a three-component system is ascribed to
secondary reactions between the coinitiators and intermediates that lead to the generation of
higher amount of initiating species and the recovery of the initial dye.