Polymer Engineering and Science, Vol.35, No.12, 989-999, 1995
Copolymerization of T-Butoxycarbonyloxystyrene and Sulfur-Dioxide
The reaction kinetics of radical chain copolymerization of t-butoxycarbonyloxystyrene (TBS) and sulfur dioxide have been studied using a reaction/sampling apparatus that permits accurate determination of the reaction mixture concentrations during polymerization. The results are compared with the styrene-sulfur dioxide copolymerization kinetics. The influence of temperature and reactant concentrations on the polymerization rate and copolymer composition are reported. With increasing reaction temperature, the amount of SO2 incorporated and the molecular weight of the copolymer are found to decrease. For a constant TBS concentration in the reaction solution, raising the SO2 concentration causes an increase of SO2 incorporation in the copolymer, up to a maximum SO2 content corresponding to a TBS:SO2 mole ratio of 2:1. However, for a constant SO2 concentration, the amount of TBS incorporated in the copolymer increases with decreasing TBS concentration in the reaction solution. The polymerization rate and copolymer molecular weight increase proportionally with monomer concentration as expected for a normal radical chain polymerization mechanism. Comparison of these findings with various kinetic models for styrene-SO2 copolymerization indicates good agreement with models proposed by Barb (1-3) and Walling (4); however, the data do not agree with the predictions of Matsuda et al (5) The understanding of the kinetics and reaction mechanism provided in this study will aid in the manufacture of this lithographically important copolymer.