Fuente: Journal of applied polymer Lugar: RESEARCH ARTICLE A symmetric trilayer polymer dielectric with a “high insulation–high polarization–high insulation” architecture is constructed by sequential solution casting. Dielectric contrast between layers induces interfacial polarization and electric field redistribution, simultaneously enhancing breakdown strength and polarization. The optimized film achieves high energy density with low loss, demonstrating an effective structural strategy for advanced polymer film capacitors.


ABSTRACT
To overcome the challenge of simultaneously enhancing breakdown strength and dielectric constant in polymer dielectrics, this study proposes a simple layer-by-layer casting method to prepare a three-layer film. The structure features outer layers of PMMA/g-C3N4/PVDF for high breakdown strength and a central g-C3N4/PVDF layer for high dielectric constant. This “high-breakdown–high-dielectric–high-breakdown” design promotes electric field redistribution and interfacial polarization, maintaining a high dielectric constant (7.26 at 100 Hz) even with 50 wt% PMMA. Moreover, the insulating PMMA outer layers introduce deep charge traps, while embedded g-C3N4 nanosheets extend carrier migration paths, synergistically inhibiting electrical treeing. Consequently, the three-layer film achieves a breakdown strength of 647.57 MV/m at 50 wt% PMMA, about 1.15 times that of a single-layer PCP film (568.1 MV/m). More importantly, the simultaneous enhancement of polarization and breakdown strength yields an energy density of 8.22 J/cm3, 2.3 times that of pure PVDF (3.51 J/cm3). This work demonstrates a structural design strategy for breakthrough polymer dielectric performance, offering a new approach to high-performance organic dielectric films.