Zhongbo Zhang

Achieving High Dielectric Constant and Low Loss Property in a Dipolar Glass Polymer Containing Strongly Dipolar and Small-Sized Sulfone Groups

In this report, a dipolar glass polymer, poly(2-(methylsulfonyl)ethyl methacrylate) (PMSEMA), was synthesized by free radical polymerization of the corresponding methacrylate monomer. Due to the large dipole moment (4.25 D) and small size of the side-chain sulfone groups, PMSEMA exhibited a strong γ transition at a temperature as low as -110 °C at 1 Hz, about 220 °C below its glass transition temperature around 109 °C. Because of this strong γ dipole relaxation, the glassy PMSEMA sample exhibited a high dielectric constant of 11.4 and a low dissipation factor (tan δ) of 0.02 at 25 °C and 1 Hz. From an electric displacement-electric field (D-E) loop study, PMSEMA demonstrated a high discharge energy density of 4.54 J/cm(3) at 283 MV/m, nearly 3 times that of an analogue polymer, poly(methyl methacrylate) (PMMA). However, the hysteresis loss was only 1/3-1/2 of that for PMMA. This study suggests that dipolar glass polymers with large dipole moments and small-sized dipolar side groups are promising candidates for high energy density and low loss dielectric applications.

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) (SO2 -PPO) was synthesized by post-polymer functionalization. Owing to the efficient rotation of highly polar methylsulfonyl side groups below the glass transition temperature (Tg ≈220 °C), the dipolar polarization of these SO2 -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 Tg  , the SO2 -PPO25 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.