2-mercaptothioxanthone as sensitizer and coinitiator for acylphosphine oxide photomitiators for: Free radical polymerization


Keskin S. , Jockusch S., Turro N. J. , ARSU N.

MACROMOLECULES, cilt.41, ss.4631-4634, 2008 (SCI İndekslerine Giren Dergi) identifier

  • Cilt numarası: 41 Konu: 13
  • Basım Tarihi: 2008
  • Doi Numarası: 10.1021/ma800472.u
  • Dergi Adı: MACROMOLECULES
  • Sayfa Sayıları: ss.4631-4634

Özet

The initiation efficiencies of photoinitiators for free radical polymerization, 2,4,6-trimethylbenzoyldiphenylphosphine oxide (TMDPO) and bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphme oxide (BAPO), are enhanced by addition of mercaptothioxanthone (TX-SH) to the initiator formulation. The additive TX-SH combines the benefits of a triplet sensitizer (enhanced tight absorption) and-thiol functionality (reduced oxygen inhibition). On the basis of polymerization studies, laser flash photolysis, fluorescence, and phosporescence, the following mechanism is proposed: most of the light is absorbed by TX-SH to generate (3)(TX-SH)*, which transfers its energy to TMDPO and BAPO followed by alpha-cleavage to produce the initiating radicals. In addition, excellent polymerization yields were observed in air-saturated solutions when TX-SH was added. With the addition of TX-SH to initiation formulations, the inhibition due to oxygen is reduced, probably by the generation of reactive thiyl radicals by hydrogen abstraction of inactive peroxyl radicals from the thiol functionality.