Mesomorphic Structure of Poly(styrene)-block-poly(4-vinylpyridine) with Oligo(ethylene oxide)sulfonic Acid Side Chains as a Model for Molecularly Reinforced Polymer Electrolyte

We report self-organized polymer electrolytes based on poly(styrene)-block-poly(4-vinylpyridine) (PS-block<BO>-</BO>P4VP). Liquidlike ethylene oxide (EO) oligomers with sulfonic acid end groups are bonded to the P4VP block, leading to comb-shaped supramolecules with the PS-block-P4VP backbone. Lithium perchlorate (LiClO<INF>4</INF>) has been added to the EO-rich domains. Small- and wide-angle X-ray scattering in combination with Fourier transformation infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), ac impedance, and dynamic mechanical spectroscopy (DMA) suggests alternating lamellae of reinforcing glassy PS domains and ionically conducting “nanochannels” consisting of poly(4-vinylpyridinium), oligomeric ethylene oxide sulfonates, and LiClO<INF>4</INF>. The long period of the self-organization is ca. 300 Å. So far, the ionic conductivity levels remained relatively low, i.e., 10^-7−10^-6 S/cm at room temperature and 10^-5−10^-4 S/cm at 80 °C. However, as self-organization of polymeric supramolecules allows combining glassy reinforcing domains and well-plasticized domains consisting of oligomers with high segmental motions, there may exist possibilities to tune feasible combination of electrical and mechanical properties.