Hierarchical composites of conductivity controllable polyaniline layers on the exfoliated graphite for dielectric application

Hierarchical composites of polyaniline fibers on the surface of exfoliated graphite were synthesized by chemical oxidation method. The conductivity of polyaniline fibers was controlled by doping and dedoping procedures. The morphology, structure and chemical character of doped and dedoped hierarchical composites were systemically investigated by SEM, TEM, XRD, FT-IR, XPS and conductivity measurement. After dedoping procedure, polyaniline/exfoliated graphite composites were used to improve dielectric property of the electroactive polymer poly(vinylidene fluoride). The dielectric constant and loss tangent of composites were 17 and 0.06 (103 Hz) when the polyaniline/exfoliated graphite loading was 3 wt%. Of great interest was that the dielectric loss tangent of composites showed inherent low loss of poly(vinylidene fluoride) because insulating polyaniline fibers on the surface of exfoliated graphite effectively prevented direct contact of exfoliated graphite flakes in poly(vinylidene fluoride) matrix.