CONSUMPTION OF THE MOLECULAR OXYGEN IN POLYMERIZATION SYSTEMS USING PHOTOSENSITIZED OXIDATION OF DIMETHYLANTHRACENE

Abstract

It is well known that the presence of oxygen in free radical polymerization systems leads to an inhibition period and a lowered ultimate conversion. In this contribution, we report a method for consuming molecular oxygen photochemically before the polymerization takes place, thereby allowing the reaction to proceed in an oxygen-free environment. The method is based on the generation of singlet oxygen by reaction of the ground state oxygen with the excited triplet state of the singlet oxygen generator (a porphyrin, Znttp). The singlet oxygen is then consumed by reaction with a second compound (the singlet oxygen trapper, dimethylanthracene). The possible factors that might affect the efficiency of the singlet oxygen generation/trapping processes were discussed and the effectiveness of a dimethylanthracene/Znttp combination for consumption of oxygen was investigated in two acrylate systems of different viscosity.