High‐κ and High‐Temperature Dipolar Glass Polymers Based on Sulfonylated and Cyanolated Poly(Arylene Ether)s for Capacitive Energy Storage

Abstract High energy density, high temperature, and low loss dielectric polymers have drawn increasing attention in research owing to their potential applications in power electronic and pulsed power devices. In this study, a new class of organo‐soluble dipolar glass polymers (DGPs) are synthesized via polycondensation and post‐functionalization of poly(aryl ether)s (PAEs) based on phenolphthalin. Due to the nonplanar backbone structure, the strongly dipolar side groups (‐SO 2 CH 3 and ‐CH 2 CH 2 CN) can easily rotate in these PAEs. As a result, desirable physical properties are obtained: high dielectric constant (4.4–5.6), high glass transition temperature (155–180 °C), good mechanical property, and low dielectric loss (dissipation factor < 0.005). Among them, cyanolized poly(aryl ether nitrile) exhibit the highest discharged energy density of 8.6 J cm −3 at 650 MV m −1 and room temperature with a high discharged efficiency of 94.3%. At 100 °C, cyanolized poly(ether ether ketone) shows the highest discharged energy density of 7.3 J cm −3 at 600 MV m −1 with a discharged efficiency of 91%. Furthermore, these functionalized PAEs exhibit good mechanical toughness with a tensile strength at a break of 60‐120 MPa and elongation at a break of ≈5%. Based on their thermal, mechanical, and dielectric properties, these phenolphthalin‐based PAEs are promising for potential applications such as film capacitors.