Chapter 2. The Importance of Chain-Length Dependent Kinetics in Free-Radical Polymerization: A Preliminary Guide

  1. Prof. Dr. Michael Buback2 and
  2. A. M. van Herk3
  1. Johan P. A. Heuts3,
  2. Gregory T. Russell1,
  3. Gregory B. Smith1 and
  4. Alex M. van Herk13

Published Online: 31 MAY 2007

DOI: 10.1002/9783527610860.ch2

Radical Polymerization: Kinetics and Mechanism, Volume 248

Radical Polymerization: Kinetics and Mechanism, Volume 248

How to Cite

Heuts, J. P. A., Russell, G. T., Smith, G. B. and van Herk1, A. M. (2007) The Importance of Chain-Length Dependent Kinetics in Free-Radical Polymerization: A Preliminary Guide, in Radical Polymerization: Kinetics and Mechanism, Volume 248 (eds M. Buback and A. M. van Herk), Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, Germany. doi: 10.1002/9783527610860.ch2

Editor Information

  1. 2

    Institute of Physical Chemistry, Georg-August-University Göttingen, Tammannstrasse 6, D-37077 Göttingen, Germany

  2. 3

    Laboratory for Polymer Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven, The Netherlands

Author Information

  1. 1

    Department of Chemistry, University of Canterbury, Private Bag 4800, Christchurch, New Zealand

  2. 3

    Laboratory for Polymer Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven, The Netherlands

Publication History

  1. Published Online: 31 MAY 2007
  2. Published Print: 13 APR 2007

ISBN Information

Print ISBN: 9783527320561

Online ISBN: 9783527610860

SEARCH

Keywords:

  • chain-length dependent propagation;
  • chain-length dependent termination;
  • free-radical polymerization;
  • kinetics

Summary

The effect of chain-length dependent propagation at short chain lengths on the observed kinetics in low-conversion free-radical polymerization (frp) is investigated. It is shown that although the values of individual propagation rate coefficients quickly converge to the high chain length value (at chain lengths, i, of about 10), its effect on the average propagation rate coefficients, 〈kp〉, in conventional frp may be noticeable in systems with an average degree of polymerization (DPn) of up to 100. Furthermore it is shown that, unless the system is significantly retarded, the chain-length dependence of the average termination rate coefficient, 〈kt〉, is not affected by the presence of chain-length dependent propagation and that there exists a simple (fairly general) scaling law between 〈kt〉 and DPn. This latter scaling law is a good reflection of the dependence of the termination rate coefficient between two i-meric radicals, ki;it, on i. Although simple expressions seem to exist to describe the dependence of 〈kp〉 on DPn, the limited data available to date does not allow the generalization of these expressions.