ABA triblock comb copolymers with oligo(oxyethylene) side chains as matrix for ion transport

ABA triblock copolymers consisting of two terminal blocks (A) of comb‐like polymethacrylate with oligo(oxyethylene) side chains (on the average eight oxyethylene units per side chain) and a middle block B of polystyrene were synthesized by anionic polymerization. The ratios A/B were varied, and the respective polymers characterized by 1H and 13C NMR, gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). The polymers were then solution‐cast from tetrahydrofuran solutions of lithium perchlorate, and the homogeneous, solvent‐free polymer electrolyte systems tested for their thermal characteristics (DSC) and conductivity. The inclusion of a polystyrene block in the comb‐like polymethacrylate electrolyte vastly improves their film‐forming and mechanical properties, but also lowers the conductivity. Addition of dimethyltetraethyleneglycol (2,5,8,11,14‐pentaoxapentadecane) enhances the ion conduction which can reach values of 10−4 Ω−1 · cm−1 at 70°C, depending on salt and styrene content.