Revealing the correlation between molecular structure and dielectric properties of carbonyl‐containing polyimide dielectrics

ABSTRACT Polymer dielectrics with outstanding heat resistance and advanced dielectric properties are of great importance for high‐temperature capacitors in the applications of hostile circumstances. In this work, a series of aromatic carbonyl‐containing polyimides (CPI) are prepared from the carbonyl dianhydride and different diamines. The correlation between molecular structure (i.e., different linked structure (─O─, ─CH2─, ─SO2─) in diamines, the length of repeating unit and the linked position (para‐para or meta‐meta), and properties is revealed in detail to obtain CPI dielectrics with excellent thermal resistance (glass transition temperature, T g : 241~352°C), reasonably high dielectric constant (3.99~5.23), low dissipation factor (0.00307~0.00395), and admirable breakdown strength (425~552 MV/m) simultaneously. Particularly, CPI‐5 with carbonyl structure in dianhydride and sulfonyl group in diamine proves to exhibit discharged energy density and charge–discharge efficiency of 6.34 J/cm 3 and 92.3% at 500 MV/m, respectively. In addition, CPI‐5 also displays stable dielectric properties in temperature range of −50‑200°C. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136 , 47883.