Role of polyaniline coating on nanosilica particles in polyvinylidene fluoride nanocomposites for energy storage

Polymer nanocomposites, which are characterized by a high dielectric permittivity, are intensively studied for microelectronic devices and energy storage applications. Poly(vinylidene fluoride) (PVDF) has a higher dielectric permittivity among polymers, is flexible, lightweight and easy to be processed. One route to enhance its mechanical and dielectric properties is the addition of inorganic nanofillers. Therefore, PVDF was melt compounded with nanosilica in various proportions, from 5 to 30 wt%. For enhancing the stored and released electric energy densities, polyaniline (PANI) was obtained in situ on the surface of nanosilica in both acid and basic media; further the nanosilica particles coated with PANI were incorporated in PVDF by melt compounding to improve the dielectric properties by adding new interfaces. The addition of nanosilica in PVDF led to a strong increase in its storage modulus without reducing its good thermal stability. Moreover, an important increase in PVDF permittivity was determined by increasing content of nanosilica in nanocomposites. PANI coating influenced both thermal and mechanical properties and led to nanocomposites with more stable dielectric permittivity and lower dielectric loss than neat PVDF at frequencies between tens Hz and tens kHz, which is very important for energy storage applications.