NMR-STUDY OF THE PROPAGATION CENTER IN THE CATIONIC POLYMERIZATION OFN-BENZOYL-8-OCTANELACTAM .2. INVESTIGATION OF THE PROPAGATION CENTER

The nature of the propagation center in the cationic polymerization of N-benzoyl-8-octanelactam initiated by octanoylium hexachloroantimonat e, SbCl5, and Ph3CAsF6 in perdeuterated tetrachloroethane or its mixtu re with o-dichlorobenzene was studied using H-1, C-13, F-19, P-31, As- 75, and Sb-121 nuclear magnetic resonance (NMR) of model oligomers and the products of their end-capping with triphenylphosphine. In all cas es, the nature of the propagation center has been found to be of an ac ylium ion pair with an SbCl6- or AsF6- counterion coordinated with the nearest benzoylamide group and cosolvated by the solvent. (C) 1994 Jo hn Wiley & Sons, Inc.