A REAPPRAISAL OF THE PHOTOPOLYMERIZATION KINETICS OF TRIETHYLENEGLYCOL DIMETHACRYLATE INITIATED BY CAMPHORQUINONE-N,N-DIMETHYL-P-TOLUIDINE FOR DENTAL PURPOSES

This work describes the characteristics of triethyleneglycol dimethacr ylate (TEGDM) polymerization when photoinitiated by camphorquinone (CQ ) alone and in the presence of N,N-dimethyl-p-toluidine (DMT) in air a nd/or in N-2. The rates of polymerization (R-p), double bond conversio n (p), monomer conversion (p(m)), temperature, and different concentra tions of CQ and DMT were measured and analyzed. The second R-p maximum was found for the polymerization of TEGDM in the presence of CQ (with out DMT) in N-2 and in the presence of CQ + DMT in air. Formation of t he second R-p maximum has been explained by the different mobility of the initiating monomer radicals in the polymer matrix as a polymerizat ion proceeds. The 2,2,6,6-tetramethylpiperidine and 4-hydroxy-2,2,6,6- tetramethylpiperidinox radicals were used in order to evaluate the rol e of amineoxy and amineperoxy radicals in the polymerization of TEGDM in air. Finally. photophysical studies allowed a more detailed evaluat ion of the role of excited states of CQ and DMT in the photoinitiation process.