Heteroaromatic Thiols as Co-initiators fot Tupe II Photoinitiating Systems

All the reactants were obtained from Aldrich. The monomer was purified by column chromatography before use. Reaction rate profiles and conversions were determined by isothermal differential scanning calorimetry. Throughout the experiments the DSC unit was operated isothermally at 40 ± 0.01°C. The 10-mg samples were polymerized in open aluminium pans with the diameter of 6.6 mm. In the case of measurements in an inert atmosphere the DSC chamber was purged with argon of high purity (<0.0005% of 02) for 10 mm prior to irradiation to remove oxygen from the chamber and that dissolved in the sample. The polymerization was initiated by the light of a halogen lamp (Phillips 500 W GY 9,5, total light intensity 415 ). For calculations the polymerization enthalpy 56 kJ/mol per one double bond for was used. Nanosecond laser flash photolysis measurements were carried out in acetonitrile solutions using 2 laser (for MBO and MBI) and YAG laser (for MBT). The reduction potentials of the initiators and oxidation potentials of the co-initiators were determined by cyclic voltammetry in acetonitrile.