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. (1997). A theoretical description of a method for model-independent determination of bimolecular chain-length-dependent free-radical-termination rate coefficients. Macromolecules, 30(22), 6743-6753. DOI: 10.1021/ma970288l General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. ABSTRACT: A theoretical description is given of a method for model-independent determination of bimolecular chain-length-dependent free-radical-termination rate coefficients. By on-line determination of the monomer concentration versus time in a time-resolved pulsed laser polymerization, the value of the termination rate coefficient kt i,i of the termination reaction between species of identical chain length can be determined in a very simple fashion. The key assumption in this kt determination is that the radical chain-length distribution that is generated with a laser pulse is extremely narrow, such that all chains can be considered as being identical in chain length. With computer simulations the effects of several processes which could undermine this key assumption were investigated. For the monomer methyl methacrylate (MMA) the effects of (i) a Poisson distribution of the polymerization events, (ii) chain transfer to monomer, and (iii) the presence of a background initiation process were investigated. For MMA, none of these processes interfere with the model-independent determination of the termination rate coefficients, as long as suitable experimental conditions are chosen, which follow from the simulations.

SUMMARY:The propagation rate coefficient of the terpolymerization of styrene, methyl methacrylate and methyl acrylate in bulk was successfully determined at three different monomer compositions. The temperature was varied between 18 and 80°C. The resulting data at 50°C were not in agreement with predictions according to the terminal model with binary reactivity ratios that have been determined by fitting copolymer composition data with the terminal model. This indicates that here also the penultimate unit affects the kinetics.