Polyvinylidene fluoride (PVDF)/polyacrilonitrile (PAN)/multiwalled carbon nanotubes functionalized COOH (MWCNTs-COOH) nanocomposites with different contents of MWCNTs were fabricated by using electrospinning and solution cast methods. The interaction of the MWCNTs with the polymer blend was confirmed by a Fourier transform infrared (FTIR) spectroscopy study. The dispersion of the MWCNTs in the polymer blend was studied by scanning electron microscopy. The dispersion of the MWCNTs in the polymer matrix at different compositions has been examined by using scanning electron microscopy (SEM). Both individual and agglomerations of MWCNTs were evident. Multiwalled carbon nanotubes are capable of enhancing the impedance and electrical conductivity of PVDF-PAN/MWCNTs in a wide frequency range at different temperatures. Nanocomposites based on PVDF/PAN and MWCNTs as fillers show a significant enhancement in the electrical conductivity as a function of temperature. In addition, PVDF/PAN with 5.58 wt.% of MWCNTs has a much higher specific energy (129.7Wh/kg) compared to that of PVDF/PAN (15.57 Wh/kg).The results reveal that PVDF/PAN/MWCNTs composites have potential applications for nanogenerators, organic semiconductors, transducers, and electrical energy storage.

Multifunctional materials have attracted many interests from both fundamental and practical aspects, such as field–effect transistor, electric protection, transducers and biosensor. Here we demonstrated the first superior hydrophobic piezoelectric surface based on the polymer blend of polyvinylidene fluoride (PVDF)–polyacrilonitrile (PAN) assisted with functionalized multiwalled nanotubes (MWNTs), by a modified electrospinning method. Typically the β–phase polyvinylidene fluoride (PVDF) was considered as the excellent piezoelectric and pyroelectric materials. However, polar β–phase of PVDF exhibited a natural high hydrophilicity. As a well–known fact, the wettability of the surface is dominated by two major factors: surface composition and surface roughness. The significant conversions derived by the incorporation of MWNTs, from nonpolar α–phase to highly polar β–phase of PVDF, were confirmed by FTIR. Meanwhile, the effects of MWNTs on the improvement of the roughness and the hydrophobicity of polymer blend were evaluated by atomic force microscopy (AFM) and contact angle (CA). Molar free energy of wetting of the polymer nanocomposite decreases with increasing the wt.% of MWNTs. All molar free energy of wetting of PVDF–PAN/MWNTs were negative, which means the non–wettability of film. The combination of surface roughness and low–surface–energy modification in nanostructured composites leads to high hydrophobicity. Particularly, fabrication of superior hydrophobic surfaces not only has fundamental interest but also various possible functional applications in micro– and nano–materials and devices.