Piezoelectric β Polymorph in Poly(vinylidene fluoride)-Functionalized Multiwalled Carbon Nanotube Nanocomposite Films

Abstract

Poly(vinylidene fluoride) (PVF2)−multiwalled carbon nanotube (MWNT) nanocomposites (PCNCs) are prepared using ester (−COOC2H5)-functionalized MWNT (F-MWNT). Due to the specific interaction of the >CO group in F-MWNT and the >CF2 group of PVF2, the dispersion of F-MWNT in PVF2 matrix is uniform. Transmission electron microscopy study reveals that the F-MWNTs in the composite are fatter than the pure F-MWNTs indicating that the PVF2 chains are wrapped on the surface of MWNTs. In the nanocomposites, the spherulitic morphology of PVF2 is lost and the fibrils are curled and smaller in length than those of pure PVF2 sample. Field emission scanning electron microscopy study indicates good dispersion of carbon nanotubes in the F-MWNT samples. The solvent-cast films have the β-polymorphic (piezoelectric) structure for F-MWNT concentration ≥1% (w/w) and have a mixture of α and β polymorphs below that concentration of F-MWNT. In the melt-cooled specimen, there occurs a mixture of α and β polymorphs and the latter is...