Improved dielectric properties of PVDF nanocomposites: a comparative study of noncovalent and covalent functionalization of MWCNTs

Polyvinylidene fluoride (PVDF) based nanocomposites with gamma-oxo-pyrenebutyric acid-noncovalent modified multiwalled carbon nanotubes (denoted as PACNTs) and stearic acid-covalent modified MWCNTs (SACNTs) as nanofillers, were fabricated using solution-blending method and their dielectric properties were carefully investigated. gamma-Oxo-pyrenebutyric acid (PA) or stearic acid (SA) can improve the dispersion of MWCNTs in PVDF matrix because of strong physical pi-pi interaction and the surface of MWCNTs grafted with SA respectively. The values of percolation threshold for PVDF/PACNTs and PVDF/SACNTs were determined to be 5.7 and 6.3 vol%, respectively. Higher dielectric permittivity and lower loss tangent of PVDF/PACNTs originates from remarkable interfacial polarization because PA have more contact area with MWCNTs and can reduce leakage current compared with SA.