Modelling and mechanism of free-radical polymerizations are important for science and industry, but often completely different model assumptions and parameter values are reported for ostensibly the same systems. The project is to rectify this situation through international collaboration, by producing critically evaluated kinetic parameters, whose values are reliable and which can be used by the international polymer community: this is seen as fulfilling IUPAC objectives. Reliable methodologies for the goals of the present project have been established by the predecessor to this project, the IUPAC Working Party on “Modeling of Polymerization Kinetics and Processes – Benchmark Rate Parameters for Free-Radical Polymerization”. Benchmark propagation rate coefficients have been obtained for styrene and methyl methacrylate by critical evaluation and also by independent experiments (from at least two members of the WP). These efforts will be extended to all other relevant monomers with these activities already being underway for other members of the alkyl methacrylate family and for functional and cyclic methacrylates. Propagation rate coefficients of alkyl acrylates will subsequently be evaluated, as will be propagation rates in copolymerizations. Moreover, termination and chain transfer data will be evaluated by the WP. It has been decided to emphasize methods and results from pulsed laser polymerization (PLP), and to use these, in addition, to “benchmark” other methods. The current focus is on PLP-SEC (size exclusion chromatography) experiments to deduce propagation rate coefficients of free-radical homopolymerizations. Results have been obtained for a number of monomers by WP members. Novel criteria for the reliability of PLP results have been set down. Strategies for planning PLP experiments have been worked out. The experimental PLP work is accompanied by extensive theoretical studies of pulsed laser polymerization.
Project Completed – Reportsreference:
- Critically-evaluated propagation rate coefficients in free radicalpolymerizations
Critically evaluated ratecoefficients for free-radical polymerization
2. Propagationrate coefficients for methyl methacrylate
Macromol. Chem. Phys. 198, 1545-1560 (1997).
3. Propagationrate coefficients for alkyl methacrylates
Macromol. Chem. Phys. 201, 1355-1364 (2000).
> continuation: Project 2000-001-1-400