Black phosphorus nanoflakes/polyimide composite films with excellent dielectric and mechanical properties

Polyimides (PIs) and their composites hold promise as low-cost alternatives to conventional ceramic-based dielectrics. Nevertheless, they are far unsatisfactory for practice applications, mainly resulting from the low interfacial compatibility between PI matrices and inorganic fillers. Herein, black phosphorous (BP) nanoflakes/PI composite films with outstanding dielectric and mechanical properties were fabricated via an in situ polymerization pathway. Owing to the hydrophilic surface of BP nanoflakes resulting from slight oxidation during fabrication, the robust noncovalent interaction between BP and PI can be formed, leading to good interfacial compatibility between the two domains and thus well dispersion of BP in PI. Even with a low BP content of 2 wt%, the composite can reach a high-permittivity value of 8.6 at 10 2 Hz and a low dielectric loss value of 0.02. Moreover, the BP/PI composite films inherited the good mechanical performance of PI matrix due to homogeneous dispersion and low loading of BP.