Chain Length Dependence of Chain Propagation Revisited

• Published in: Macromolecules Vol. 38; no. 5; pp. 1944 - 1948
• Main Authors: Olaj, Oskar Friedrich, Zoder, Monika, Vana, Philipp, Kornherr, Andreas, Schnöll-Bitai, Irene, Zifferer, Gerhard
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 08.03.2005
• Subjects: Applied sciences; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Polymerization; Preparation, kinetics, thermodynamics, mechanism and catalysts; Free radical polymerization; Bulk polymerization; Pulsed laser; Theoretical study; Styrene polymer; Kinetics; Error correction; Rate constant; Computing method; Reaction propagation; Gel permeation chromatography
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/ma048941+

On the basis of recently developed numeric procedures, the results obtained for the propagation constants k p by means of the PLP−SEC method (pulsed laser polymerization followed by size exclusion chromatographical analysis of the chain length distribution) were subjected to a critical reevaluation and reanalysis particularly with respect to the chain length dependence of k p. In this context the errors arising from a broadening caused by axial dispersion in the SEC were largely eliminated together with other uncertainties in assessing the characteristic chain length L 0 on which the evaluation of k p is based. The main result that refers to the bulk polymerization of methyl methacrylate and styrene in the temperature range 25−70 °C is that the previously found negative long-range chain length dependence of k p survived this procedure to an extent that widely exceeds the known variation of k p for extremely short chains and extends over a range of several hundreds of propagation steps.