Aromatic poly(arylene ether urea) with high dipole moment for high thermal stability and high energy density capacitors

Developing dielectric polymers with higher dielectric constant without sacrificing loss and thermal stability is of great importance for next generation of high energy density capacitors. We show here that by replacing the CH₂ group in the aromatic polyurea (ArPU) with the polar ether group, thus raising the dipole moment of the molecular unit, poly(arylene ether urea) (PEEU) shows an increased dielectric constant of 4.7, compared with 4.2 of ArPU. Moreover, PEEU maintains the low dielectric loss and is thermally stable up to 250°C. As a result, the polymer delivers 13 J/cm³ discharged energy density at room temperature and 9 J/cm³ at 120°C. The high quality films perform well in terms of both breakdown strength (at 700 MV/m at room temperature) and leakage current from room temperature to elevated temperature. At 120°C, the breakdown strength is 600 MV/m and the conductivity is 1.58×10^-14 S/cm measured under 100 MV/m.