High Dielectric Constant Percolative Nanocomposites Based on Ferroelectric Poly(vinylidene fluoride) and Acid-Treatment Multiwall Carbon Nanotubes

In this communication, multiwall carbon nanotubes (MWNT) treated in the mixture HNO₃/H₂SO₄ acids (MWNT-A) were dispersed into poly(vinylidene fluoride) (PVDF) by using a solution method to form the MWNT-A/PVDF nanocomposite without any MWNT-A aggregation. The result showed that there was a strong interaction between MWNT-A and PVDF, which was due to the acid-treatment process for MWNT. The MWNT-A in the composites played an important role on deciding the crystallization structure of the PVDF used because they can insert PVDF molecules and have an effect on the crystallization of PVDF polymer. High dielectric constant ( epsivap800 ) was discovered in the MWNT-A/PVDF nanocomposite when the concentration of MWNT-A was close to percolation threshold (about 0.065 in volume fraction). The threshold was very low because the MWNT-A had a high aspect ratio, little impurity and amorphous carbon. The MWNT-A/PVDF percolation nanocomposites also exhibited extremely higher conductivity than that of pure PVDF polymer. These results clearly indicated that such PVDF-based composites at the nanoscale hold the promise of creating some novel dielectric materials applied in electromagnetic wave absorption field