Low percolation transitions in carbon nanotube networks dispersed in a polymer matrix: dielectric properties, simulations and experiments

Abstract

The low concentration behaviour and the increase of the dielectric constant in carbon nanotubes/polymer nanocomposites near the percolation threshold are still not well understood. In this work, a numerical model has been developed which focuses on the effect of the inclusion of conductive fillers in a dielectric polymer matrix on the dielectric constant and the dielectric strength. Experiments have been carried out in carbon nanotubes/poly(vinylidene fluoride) nanocomposites in order to compare to the simulation results. This work shows how the critical concentration is related to the formation of capacitor networks and that these networks give rise to high variations in the electrical properties of the composites. Based on numerical studies, the dependence of the percolation transition on the preparation of the nanocomposite is discussed. Finally, based on numerical and experimental results, both ours and from other authors, the causes of anomalous percolation behaviour of the dielectric constant are identified.

Multifunctional nanocomposites of poly(vinylidene fluoride) reinforced by carbon nanotubes and magnetite nanoparticles

“…The distribution of CNT within the insulating polymer matrix, except the formation of donor-acceptor complexes at the PVDF-CNT interface [40], forms lots of nanocapacitors connected not only in series but also in parallel combinations, while this nanocapacitor's formation can significantly improve the dielectric permittivity of the nanocomposites [44,45]. Of course, the presence of the magnetite inclusions is expected to affect this nanocapacitors formation.…”

Low-temperature fabrication of titanium metal/barium titanate composite capacitors via hydrothermal method and their dielectric properties

“…A series of conductor/insulator composite materials categorized as percolation materials have attracted much attention because these composites exhibit the outstanding dielectric properties. Actually, a large amount of researches on these composites capacitors such as metal/ dielectrics, 1),2) metal/polymer, 3), 4) and carbon/polymer 5) composites has been undertaken and they are expected to be applied to sensors, 6),7) tunable filters, 8) and energy-storage devices. 9) In general, the effective dielectric constant of such conductor/ insulator composite materials increases with a content of the conductive particles distributed in the insulator layers, and a drastic increase in the effective dielectric constant is up to several orders of magnitude close to a percolation threshold (an insulator to metal transition point).…”

Osteoblast, fibroblast and in vivo biological response to poly(vinylidene fluoride) based composite materials

“…The preparation of the most recent PVDF-based composites aims to improve the polymer piezoelectric properties and/or to add new and interesting properties for distinct applications. In particular, the addition of magnetic nanoparticles allows to obtain magnetoelectric and multiferroic composites for sensors and cell stimulation [9]; the addition of Ag particles allows larger dielectric response and antimicrobial properties [10]; the zeolites addition allows increasing dielectric properties, functional properties, and controlled drug release [11]; the ceramic fillers to improve electroactivity [12] and the addition of carbon nanotubes increases dielectric and mechanical properties [13]. On the other hand, once fillers have been introduced into the polymer matrix, biomaterial-cell interaction is modified and novel bioactivity or even suppression of biocompatibility can occur [14,15].…”