Living cationic polymerization route to poly(oligooxyethylene carbonate) vinyl ethers

The addition of dialkyl (R = Me or Et) carbonates to poly(oxyethylene)-based solid polymeric electrolytes resulted in enhanced ionic conductivities. Relatively high conductivities in lithium batteries with solutions of lithium salts in di(oligooxyethylene) carbonates such as R(-OCH₂-CH₂-)_nOC(=O)-O-(-CH₂CH₂ O-)_mR (R = Et, n = 1, 2, or 3, m = 0, 1, 2, or 3) and related carbonates were obtained. In this respect, related comb-shaped poly(oligooxyethylene carbonate) vinyl ethers of the type -CH₂CH(OR)-were prepared [R = (-OCH₂-CH₂-)_nOC(=O)-O-(-CH₂CH₂ O-)_mR'; (1) n = 2 or 3, m = 0, R' = Et; (2) n = 2 or 3; m = 3, R' = Me]. The direct preparation of derived target polymers of this class by polymerization of the corresponding vinyl ether-type monomers could not be achieved because of a rapid in situ decarboxylative decomposition of these monomers (as formed) during the final step of their synthesis. Instead, a prepolymer was prepared by a living cationic polymerization of CH₂=CH-(OCH₂CH₂-)_n-O-C(=O)-CH₃ (n = 2 or 3). The hydrolysis of its pendant ester groups, followed by the reaction of the hydrolyzed prepolymer with each of several alkyl chloroformates of the type Cl-C(=O)-O(-CH₂CH₂O-)_mR' (m = 0, 2, or 3, R' = Me or Et) resulted in the corresponding target polymers.