Enhanced dielectric performance of polyvinylidene fluoride composites with an all-carbon hybrid architecture: vertically aligned carbon nanotube arrays on graphite nanoplatelets

Abstract

Carbon nanotubes (CNTs) serving as nano-fillers could endow polymer-based composites with excellent functionalities. However, a challenge always lies in the strong aggregation of loaded CNTs which hinders the sufficient improvement of composites’ properties. Here we describe polyvinylidene fluoride-based nanocomposites that contain graphite nanoplatelet–carbon nanotube hybrids (GCHs), the dielectric properties of which are improved more greatly than those of the general ternary composites loading an equivalent mixture of GNPs and CNTs. The permittivity and AC conductivity of a composite with 10 wt% GCHs are 3217 and 10⁻³ S m⁻¹ at 1 kHz, respectively, which are correspondingly 105 times and 5 orders of magnitude larger than those of ternary composites with 10 wt% mixture (30.2 and 10⁻⁸ S m⁻¹). Through the catalyst chemical vapor deposition process, the vertically-aligned CNT arrays were well synthesized on exfoliated GNP substrates, forming a totally-conductive GCHs architecture. The nanocomposites achieved by dispersing GCH particles into the matrix using a mechanical melt-mixing process show a strongly reduced percolation threshold (5.53 vol%) and a relatively high thermal stability compared to their ternary counterparts. Their improved dielectric properties can be attributed to the formed microcapacitor networks and the change of crystalline phase composition of the matrix, caused by well-designed CNT array constructions. These results indicate that the dielectric performance and percolation threshold of nanocomposites could be effectively ameliorated through the strategy of reasonably redesigning the CNT constructions.