Transport through ionic layers in sulfonated telechelic polyethylenes

We present a set of sulfonated telechelic polyethylene ionomers that demonstrate ion transport of metal cations within ionic aggregates in a crystalline polymer matrix. These precise ionomers consist of 23 or 48 backbone carbons with sulfonic acid end groups that are fully neutralized by a counterion, Li⁺ or Na⁺. Depending on spacer length and counterion, these telechelics exhibit multiple order-order transitions at T<T_m and order-disorder transitions at T~T_m, with melting points up to 300°C, as evident in both differential scanning calorimetry and X-ray scattering. At room temperature, the most common morphology is well-defined nanoscale ionic layers with a crystalline polymer backbone. The temperature-dependent ionic conductivity is characterized using electrical impedance spectroscopy. While ion transport appears decoupled from the polymer backbone at T<T_m under certain conditions, the conductivity remains quite low.