Highly Conductive Multifunctional Graphene Polycarbonate Nanocomposites

Abstract

Graphene nanosheet-bisphenol A polycarbonate nanocomposites (0.027-2.2 vol %) prepared by both emulsion mixing and solution blending methods, followed by compression molding at 287 °C, exhibited dc electrical percolation threshold of ∼0.14 and ∼0.38 vol %, respectively. The conductivities of 2.2 vol % graphene nanocomposites were 0.512 and 0.226 S/cm for emulsion and solution mixing. The 1.1 and 2.2 vol % graphene nanocomposites exhibited frequency-independent behavior. Inherent conductivity, extremely high aspect ratio, and nanostructure directed assembly of the graphene using PC nanospheres are the main factors for excellent electrical properties of the nanocomposites. Dynamic tensile moduli of nanocomposites increased with increasing graphene in the nanocomposite. The glass transition temperatures were decreased with increasing graphene for the emulsion series. High-resolution electron microscopy (HR-TEM) and small-angle neutron scattering (SANS) showed isolated graphene with no connectivity path for insulating nanocomposites and connected nanoparticles for the conductive nanocomposites. A stacked disk model was used to obtain the average particle radius, average number of graphene layers per stack, and stack spacing by simulation of the experimental SANS data. Morphology studies indicated the presence of well-dispersed graphene and small graphene stacking with infusion of polycarbonate within the stacks.

Graphene-philic surfactants for nanocomposites in latex technology

“…There has been significant experimental and theoretical effort, aimed to harness the properties of interest in graphene by improving dispersion in polymer matrices using surfactants [27,28,42,115]. It has been recognized that the behavior of surfactants in dispersing graphene is similar to that with carbon nanotubes and other carbon materials [69,83,97].…”

“…Studies have reported that surfactants can mediate filler-polymer interactions and enhance the filler-tomatrix transfer properties [42,44,69,70,78], though different conclusions were reached.…”

“…Other work published by Yoonessi and Gaier [42], describes polymers containing carbonyl groups in the polymer backbone, namely polycarbonate (PC). Polycarbonate is one thermoplastic polymer with outstanding thermal and mechanical properties to be applied as air-vehicle components [180].…”

“…Although the so-called latex technology provided remarkable results, the authors preferred to choose composites prepared with solution mixing to explore in more detail using small-angle neutron scattering (SANS) [42]. Therefore, important information relating to the surfactant-stabilized graphene dispersions such as surfactant self-assembly on graphene surfaces remains unexplored.…”

“…All of these results would surely meet industrial needs for advancing the routes in developing high performance light weight polymer composites (low graphene content) for aircraft components, thermally conductive supports for thermal management in electronic devices and engineering applications such as antistatic and electromagnetic interference [42,78,170].…”