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Ionomeric networks (IN) with lithium sulfate and salt-solvating oligo(oxyethylene) chain were synthesized on the purpose of improving the conductivity of single-Li+−ionic conductors. Li+−ionic conductivity depends considerably on the salt content of the INs although the apparent degree of cross-linking is fixed in a constant of 10 mol%. As salt content (Li/O value) equals 0.0467, conductivity of the IN containing neither small-molecular salt nor low molecular weight plasticizer reaches a maximum of 7×10−6 S/cm at 25°C. Temperature-conductivity relationship of the INs shows curved Arrhenius plots, suggesting that the ionic conduction is primarily influenced by segmental motion of the polymer host. In addition, WLF (Williams-Landel-Ferry) equation is used to analyze the conductivity data, from which the related WLF parameters are determined.

Sodium 2-methacryloyl 3-[ω-methoxyl oligo(oxyethylene)] propylsulfonate was synthesized, from which homopolymer-based polyelectrolyte was prepared. The polyelectrolytes thus obtained show single Na+ionic conductivity at ambient temperature, neither adding plasticizer nor hybridizing small molecular salt. The conductivity depends considerably on the length of oligo(oxyethylene) side-chain. Optimally, the highest conductivity of 6.0 × 10−6 S/cm at 25°C is obtained when the number of (CH2CH2O) repeating units equals 16. Results indicate that the conductivity data follow WLF and VTF equations. The WLF parameters are found to be comparable with “universal” values, and analysis of the configuration entropy model suggests that the conduction of Na+ ions is carried out by an association mechanism.

Oligo(oxyethylene) macromonomers bearing sodium sulfonate group have been synthesized through four reactions: (1) ring-opening polymerization of oxirane, (2) etherification of monomethoxyl oligo(oxyethylene) and epichlorohydrin, (3) sulfonation of cycloxyl compound, and (4) end-capping of sodium oligo(oxyethylene) sulfonate by methacrylic group. A desired length of oligo(oxyethylene) in the macromonomers can easily be achieved by controlling the ratio of reactants in the ring-opening step. The structures of the products of each reaction were identified by IR, 1H-NMR, and GPC. Polymers of the monomers were also characterized by GPC and DSC. © 1993 John Wiley & Sons, Inc.