Synthesis of polymers containing pseudohalide groups by cationic polymerization—12. Polymerization of 2-methyl-propene initiated by the system DI(1-azido-1-methylethyl)-1,4-benzene/boron trichloride

Abstract

The polymerization of 2-methylpropene (MP) initiated by the system di(1-azido-1-methylethyl)-1, 4-benzene (DAMEB)/boron trichloride in CH 2Cl 2 solution was carried out at different temperatures and with different ratios R = [BCl 3] [DAMEB] . At low temperature and for R higher than 2, the functionalities F N3 and F φ determined by FT i.r. and 1 1H NMR were higher than the theoretical values respectively of 2 and 1. Polymer analysis also indicates the presence of tert-butyl, tert-chlorine and terminal unsaturations. These results can be explained assuming that BCl 3, a strong Lewis acid, can promote predominantly the dehydroazidation reaction of DAMEB giving rise to the formation in situ of α-methyl-styrene derivative, and the copolymerization of this latter with MP. HN 3 and/or H 2O/BCl 3 combination can also initiate the MP polymerization leading to the formation of tert-butyl head-group. The presence of tert-chlorine and azide end groups comes from the competition of two termination reactions: the recombination of the electrophilic moiety with Cl − and N 3 − from the counterion.