Synthesis and characterization of homo- and copolymers of 3-(2-cyano ethoxy)methyl- and 3-[methoxy(triethylenoxy)]methyl-3'-methyl-oxetane

Two oxetane-derived monomers 3-(2-cyanoethoxy)methyl- and 3-(methoxy(triethylenoxy)) methyl-3′-methyloxetane were prepared from the reaction of 3-methyl-3′-hydroxymethyloxetane with acrylonitrile and triethylene glycol monomethyl ether, respectively. Their homo- and copolyethers were synthesized with BF₃ · Et₂O/1,4-butanediol and trifluoromethane sulfonic acid as initiator through cationic ring-opening polymerization. The structure of the polymers was characterized by FTIR and¹H NMR. The ratio of two repeating units incorporated into the copolymers is well consistent with the feed ratio. Regarding glass transition temperature (T_g), the DSC data imply that the resulting copolymers have a lower T_g than pure poly(ethylene oxide). Moreover, the TGA measurements reveal that they possess in general a high heat decomposition temperature. The ion conductivity of a sample (P-AN 20) is 1.07 × 10^-5 S cm^-1 at room temperature and 2.79 × 10^-4 S cm^-1 at 80°C, thus presenting the potential to meet the practical requirement of lithium ion batteries for polymer electrolytes.