The propagation kinetics of methyl methacrylate (MMA) in the presence of a number of oxygen- and sulfur-containing compounds have been investigated. Solvents used were 2-methyl-1,3-dioxepane (MDOP), 2,6-dithiaheptane (DTHP) and 1,5-dithiacyclooctane (DTCO). In the presence of DTHP and DTCO, the propagation rate coefficient, kp, of MMA was found to be 25% to 100% higher compared to bulk polymerisations under the same conditions. The significant increase of kp was explained by electron donation from the sulfur-containing solvents, which increased the reactivity of the macroradicals. MDOP had no observable effect on kp. The solvent influence on polymer tacticity was also studied using both 1H and 13C NMR spectroscopy. No significant influence of the solvent on polymer tacticity was found.
- Free Radical Polymerization
- Propagation Rate Coefficients
- Solvent Effects