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A novel approach is described to obtain polymers which show significant lithium ion conductivity when blended with lithium salts. Polymerization of acrylates and methacrylates with 2-oxo-1,3-dioxolane (cyclic carbonate) containing side chains gives polymers which contain the structural element of the prototypical solvent propylene carbonate (PC) firmly attached to the polymer host. (2-Oxo-1,3-dioxolane-4-yl)methyl methacrylate (DOMA) and the corresponding acrylate (DOA) were obtained by reaction of the (meth)acryloyl chloride with glycerol carbonate while (2-oxo-1,3-dioxolane-4-yl)butyl methacrylate (DOBMA) and the respective acrylate (DOBA) were obtained from the ω-hexenyl esters by first epoxidation followed by CO 2 -insertion into the oxirane ring. Free radical polymerization in DMF gave the desired polymers. All homopolymers were thermally stable at least up to 200 °C; the glass transition temperature was found for PDOMA at 93 °C, for PDOA at 50 °C, for PDOBMA at 16 °C, and for PDOBA at 11 °C. Free radical copolymerization of DOMA with butyl methacrylate (BMA) (r 1 ) 1.24, r 2 ) 0.80) gave copolymers with T g dependent on the BMA content. Blends of the homopolymers with lithium bis(trifluoro)methane sulfonimide (LiTFSI) gave appreciable lithium ion conductivities, particularly for blends of PDOA (3.7 × 10 -6 S cm -1 at 40 °C) which could be substantially increased by further blending with small amounts of propylene carbonate. These blends of honey-like consistency showed conductivities of 1.8 × 10 -3 S cm -1 (40 °C) for PDOA and 5.1 × 10 -4 S cm -1 (40 °C) for PDOBMA each blended with LiTFSI and PC at equimolar amounts. The temperature dependence of lithium ion conductivity follows a WLFtype behavior in all cases; however, the reference temperatures do not bear any correspondence to the observed glass transition temperatures but are estimated from modified WLF-plots to be positioned in a temperature regime typical for local side chain relaxations in common polymers.

Poly(alkylene biguanides) are novel high‐temperature proton conductors. This long‐known class of polymers is presented as surprisingly stable high‐temperature proton‐conducting materials in the form of water‐free HCl conjugates. Proton conductivity is dominated by free volume relaxation. Application in the context of fuel‐cell membranes is discussed.

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