Synthesis of crystalline polyamide for synergistically strengthening anticorrelated mechanical property and high-temperature capacitive energy storage

High-temperature resistant polymer dielectrics present large application potentials in harsh-environment electrostatic capacitors. However, the widely used polymer films including polyimide often suffer poor mechanical strength or energy storage level especially at superimposed bending, electrical and thermal stresses during practical operation, owing to the inherent contradiction in synergistically strengthening both sides, which is a challenging problem that urgently needs to be solved. Here an all-organic synthesis route is exploited to synergistically realize high mechanical strength (378.3 MPa), breakdown strength (682 MV/m), energy density/efficiency (6.06 J/cm³ at η = 90%, the peak value reaches 10.29 J/cm³) at 150 °C in fabricated crystalline polyamide film, which respectively has an enhancement (81%, 88%, 2231%) than that of polyimide film, whose comprehensive performances present definite preponderance among existed polymer dielectrics. It is further demonstrated that, different from traditionally disadvantageous π-π and charge-transfer interactions, the particular coexistence of abundant and strong hydrogen bonds constraining large energy gap synergistically strengthens the anticorrelated mechanical and energy-storage performances, and the matched high film crystallinity establishing by Lewis acid and high temperature-assisted chain arrangement further strengthens both sides. Compared with nanocomposite strategy, such all-organic structure also endows it with large potential to match current production process toward large-scale fabrication of high-quality polymer dielectrics.