High‐Temperature and High‐Energy‐Density Dipolar Glass Polymers Based on Sulfonylated Poly(2,6‐dimethyl‐1,4‐phenylene oxide)

A new class of high‐temperature dipolar polymers based on sulfonylated poly(2,6‐dimethyl‐1,4‐phenylene oxide) (SO 2 ‐PPO) was synthesized by post‐polymer functionalization. Owing to the efficient rotation of highly polar methylsulfonyl side groups below the glass transition temperature ( T g ≈220 °C), the dipolar polarization of these SO 2 ‐PPOs was enhanced, and thus the dielectric constant was high. Consequently, the discharge energy density reached up to 22 J cm −3 . Owing to its high T g , the SO 2 ‐PPO 25 sample also exhibited a low dielectric loss. For example, the dissipation factor (tan δ) was 0.003, and the discharge efficiency at 800 MV m −1 was 92 %. Therefore, these dipolar glass polymers are promising for high‐temperature, high‐energy‐density, and low‐loss electrical energy storage applications.