Polypyrrole random-coil induced permittivity from negative to positive in all-organic composite films

Percolating composites with negative permittivity can be promising candidates for metamaterials. Herein, novel all-organic composite films containing of random coil polypyrrole (PPy) and poly(vinylidene fluoride) (PVDF) are fabricated via a solution casting method. The random coil PPy is prepared by oxidative template assembly approach for the first time. The experimental result indicates that the negative permittivity is easily adjusted through controlling the random coil PPy contents. Especially, the random coil PPy contents exceeded 7 wt% the negative permittivity appear attributed to the formation of 3D interconnected PPy network. This facile approach not only opens a new way to preparing negative permittivity of all-organic composite films, but also points out a route to facilitate the practical applications of metamaterials.