Synergistically enhanced dielectric, insulating and thermally conductive performances of sandwich PMMA based dielectric films

A tri-layered (B-G-B) dielectric films were simply prepared by alternatively spin-coating boron nitride/polymethylmethacrylate (BN/PMMA, B) and graphene nanosheets (GNS/PMMA, G) compound solutions. The structure, morphology, thermal conductivity, and particularly the dielectric and relaxation behaviors were systematically studied. Results showed that a good exfoliation and dispersion of BN and GNS can be simply achieved through intensive mechanical compounding with PMMA in the internal mixer. The dielectric constant and breakdown strength of the obtained 1-3-1 (B-G-B) sandwich composite film reached 4.3 (@1 ​kHz) and 458.6 ​kV/mm, being 119 ​% and 113 ​% higher than that of pure PMMA, respectively. Furthermore, the overall thermal conductivity of sandwich 1-3-1 composite increased by 112 ​% due to the addition of thermally conductive BN and GNS. The sandwich design strategy provided an effective way of achieving good permittivity, high insulation, and improved thermal conductivity simultaneously, showing potential applications in the miniaturization and integration of electronic devices.