Ionic liquid type cations in anionic polyurethane ionomer: Effects on thermal and dielectric properties

Single-ion conductors have potential utility for electronic devices like battery membranes, actuators and other applications. For such applications, both high ionic conductivities and high modulus are desirable. To achieve these two goals, polyurethane ionomers can be suitable candidates: the hydrogen bonded hard phase provides good modulus while the soft phase (PEO in our system) can still facilitate ion transportation. However, the presence of ions such as sodium ions usually elaborates soft phase T_g and resulting in low ionic conductivity. By introducing ionic liquid type cations we can reduce the soft phase T_g and significantly improve ionic conductivity. To further increase ionic conductivity, we attached ether-oxygens on the cations and demonstrate that the cations with ether-oxygens can self-solvate and have higher mobility and conducting ion concentration without changing T_g too much.