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/

The polymerization of 2-methylpropene (MP) initiated by the system di( 1-azido-1-methylethyl)-1,4-benzene (DAMEB)/boron trichloride in CH2Cl2 solution was carried out at different temperatures and with different ratios R = [BCl3]/[DAMEB]. At low temperature and for R higher than 2 , the functionalities F-N3 and F-phi determined by FT i.r. and H-1 NMR were higher than the theoretical values respectively of 2 and 1. Poly mer analysis also indicates the presence of tert-butyl, tert-chlorine and terminal unsaturations. These results can be explained assuming th at BCl3, a strong Lewis acid, can promote predominantly the dehydroazi dation reaction of DAMEB giving rise to the formation in situ of alpha -methyl-styrene derivative, and the copolymerization of this latter wi th MP. HN3 and/or H2O/BCl3 combination can also initiate the MP polyme rization leading to the formation of tert-butyl head-group. The presen ce of tert-chlorine and azide end groups comes from the competition of two termination reactions: the recombination of the electrophilic moi ety with Cl- and N-3(-) from the counterion.