Manipulating epoxy-polycarbonate sandwich films with enhanced dielectric performance via solution-immersion process

Epoxy-polycarbonate sandwiched films with enhanced dielectric performance were prepared in this study. Unlike traditional tedious multiple scratch-coating approach, the sandwich dielectric films were prepared based on a convenient solution-immersion process. Polycarbonate solutions with different concentration were applied to adjust the film composition and compared with epoxy-polycarbonate blending film. We found that rather than deteriorating the breakdown strength as shown in the blending counterpart, sandwiched films prepared by solution immersion shows superior breakdown strength (709.6 MV/m), almost 40 % better than both epoxy and polycarbonate components. Moreover, tan δ of the films prepared from solution-immersion (<0.005) is apparently smaller than blending samples (∼0.008). Both factors lead to admirable ideal dielectric energy storage performance (8.44 J/cm³) of the film, better than many conventional polymers.