Raising the performances of copoly(ether-imide) films by structural design modulation towards energy storage applications

Abstract

The present study aims to shed light onto the influence of structural design on the overall properties of a series of aliphatic–aromatic CN-based copoly(ether-imide)s, with emphasis on energy storage performance, with the support provided by selected benchmarks. To boost the energy storage capability of the free-standing films made therefrom, three molar ratios of a CN-aromatic hard segment and a Jeffamine-based soft component were used. Thus, through different chemical strategies and their synergism, the films morphology and their physico-chemical properties like wetting, optical, mechanical, thermal, dielectric and, particularly breakdown strength and energy storage were modulated. The results showed high thermal stability, single glass transition temperatures, good mechanical properties, and relative low dielectric constants of the copolymers. The absence of crystallization demonstrated the amorphous nature of the films due to the good interpenetration of soft and hard components, although some phase separations were observed in some copolymers with no clearly defined boundaries. Due to the balanced thermal stability, dielectric behavior, mechanical features, and film processing ability, these copoly(ether-imide)s display potential applications in high-temperature energy storage field, reaching breakdown strength and energy storage density values up to 459 kV/mm and 2.70 J/cm3, respectively.