Enhanced dielectric properties of PVDF polymer nanocomposites: A study on gold−decorated, surface−modified multiwalled carbon nanotubes

Abstract

The integration of surface-modified multiwalled carbon nanotubes (fMWCNTs) into polymer nanocomposites has been extensively studied for their potential to enhance dielectric properties. This study, however, pioneers the use of a novel hybrid filler comprising fMWCNTs coated with metal nanoparticles, specifically aimed at augmenting the dielectric performance of polymers. In our research, poly(vinylidene fluoride) (PVDF) nanocomposite films were synthesized using fMWCNTs with a diameter of ∼6–9 nm and a length of 5 μm, adorned with gold nanoparticles (nAu) of ∼5.4 ± 0.9 nm via an adapted Turkevich method. Comprehensive analyses were conducted on nAu−fMWCNTs hybrid powder and their nanocomposites in PVDF with varying filler concentrations, confirming the formation of nAu−fMWCNTs with a weight ratio of 1.1 : 98.9. Three−phase percolative nanocomposites were produced by dispersing the hybrid filler in N,N−dimethylformamide, facilitated by interactions between the negative charge of nAu−fMWCNTs (zeta potential of ∼ −40.43 ± 0.46 mV) and polar phases of PVDF. This was verified through zeta potential and Fourier−transform infrared spectroscopy analyses. The dielectric permittivity (ε′) of the nanocomposites significantly increased from 17.8 to 524.8 (at 1 kHz) with filler loadings from 0.005 to 0.01 vol%, while the dielectric loss tangent (tanδ) showed a minor increase from 0.05 to 1.18. These enhancements are attributed to the elevated permittivity of nAu−fMWCNTs hybrid powder, PVDF's transition to the β−phase, and interfacial polarization effects. The restrained growth of nAu on fMWCNTs and the inhibition of conductive pathways in the polymer matrix contributed to the low tanδ values.