Improving the Knowledge and Design of End Groups in Polymers Produced by Free Radical Polymerization W. Ken Busfield, 1 * Ian D. Jenkins, 1 Tomoyuki Nakamura, 1,2 Michael J. Monteiro, 1 Ezio Rizzardo, 3 Shuji Sayama, 2 San H. Thang, 3 Phuc Van Le 1 and Clovia I. Zayas-Holdsworth 1 1 Faculty of Science and Technology, Griffith University, Nathan, Queensland 4111, Australia 2 Fine Chemicals and Polymers Research Laboratory, NOF Corporation, Taketoyo-cho Chita-gun, Aichi-Ken 470-23, Japan 3 CSIRO, Division of Chemicals and Polymers, Private Bag 10, Rosebank MDC, Clayton, Victoria 3169, Australia ABSTRACT Several techniques have been used to probe polymer end groups. The nitroxide radical trapping technique has been used (i) to show that initiator-derived unsaturated end groups in polymethyl methacrylate can be minimized by using t-hexyl peroxypivalate as the initiator (ii) to predict the end and penultimate groups in acrylonitrile/ethyl vinyl ether copolymer produced by t-butoxyl initiation by analogy with the initiation mechanism (iii) to predict probable end groups in polyacrylonitrile and polystyrene produced by cyanoisopropyl initiation in the presence of adventitious oxygen. NMR techniques have been used to show that the end groups of functionalized oligomers, made from styrene and methacrylonitrile by the addition- fragmentation chain transfer technique with allylic sul- phides, conform to the expected structures © 1998 John Wiley & Sons, Ltd. Polym. Adv. Technol. 9, 94–100 (1998) KEYWORDS: nitroxides; functionalized oligomers; polymer end-group control; free radical polymerization INTRODUCTION For many years the main thrust of research into the development of polymers has been on the physical and chemical modification of the wide range of existing polymers, aimed at improving properties and extending their application. Research on the discovery of new polymers has been less extensive and mainly restricted to small scale specialty materi- als. The work on physical modification, including techniques such as annealing, quenching, drawing, etc., has led not only to improved properties, but to a greater understanding of the morphological struc- ture of polymers. Likewise, the work on chemical modification, including new methods of synthesiz- ing traditional polymers, is leading to a vastly improved knowledge of the detailed chemical struc- ture of polymers, (including functional groups, branches, crosslinks, end groups and chain length) and how it relates to properties. A major develop- ment in this area of polymer science, often referred to as polymer architecture, was by Michael Szwarc with his now classic work on anionic polymerization [1].  * Correspondence to: W. K. Busfield, Faculty of Science and Technology, Griffith University, Nathan, Queensland 4111, Aus- tralia. Contract grant sponsor: Griffith University. Contract grant sponsor: ARC. Contract grant sponsor: CSIRO. Contract grant sponsor: IDP. Contract grant sponsor: NOF Corp. CCC 1042–7147/98/010094–07 $17.50 Received 6 September 1996 © 1998 John Wiley & Sons, Ltd. Revised 1 November 1996 Polymers for Advanced Technologies Volume 9, pp. 94–100