Synthesis of copolymers of 3-acryloyloxymethyl- and 3-[2-methoxy (triethylenoxy)] methyl-3'-methyloxetane and their ionic conductivity properties

The copolymer PAM, derived from two oxetane monomers 3-acryloyloxymethyl-3'-methyloxetane (AMO) and 3-[2-methoxy (ethylenoxy)] methyl-3'-methyloxetane (MEMO), was synthesized through cationic ring-opening polymerization. The ¹H-NMR results revealed that the enchained ratio of AMO in the copolymers was far less than the feed ratio as calculated. The copolymers were crosslinked through the radical polymerization of the vinyl groups in AMO after doped with the lithium salt LiTFSI to fabricate tough polymer electrolyte films. The ionic conductivity was measured at varying content of AMO and different concentration of LiTFSI by AC impedance, of which PAM33 showed a maximum ion conductivity of 1.44 × 10^-5 S/cm at 30°C and 1.25 × 10^-4 S/cm at 80°C at the ratio of n(O):n(Li)=20. DSC results indicated that T_g decreased with the increase in the proportion of AMO in the copolymer. It was well consistent with the ion conductivity results.