Synthesis and structure characterization of 3, 3'-bisazidomethyloxetane-3-azidomethyl-3'-methyloxetane random copolymer

3, 3'-Bisazidomethyloxetane-r-3-azidomethyl-3'-methyloxetane random copolymer [p(BAMO-r-AMMO)] was synthesized by cationic ring opening polymerization using 1, 4-butanediol/BF₃/Et₂O initiator system. Polymerization mechanism of active chain end and activated monomer was discussed in the presence of Lewis acid. The effect of polymerization temperature on molecular weight and molecular weight distribution of product was analysed by GPC. The results indicate that molecular weight is controllable and molecular weight distribution is relatively narrow under 15°C. ¹H NMR and ¹³C NMR were also used to character composition and micro-sequential structure of random copolymer. The results show that the composition of copolymer is 1:1, which is accordance with molar feed ratio of monomers; alternating degree is nearly 50%; average sequence length of chain segment is 2 for both BAMO and AMMO, so the two structural units are in random distribution.