Percolation threshold and electrical conductivity of graphene-based nanocomposites with filler agglomeration and interfacial tunneling

TL;DR: The differential scanning calorimetry (DSC) measurement indicates that the incorporation of GO and rGO has a remarkable impact on the crystallinity of the nanocomposites and the high performances of the PTT-block-PCL-T-based nanocom composites are mainly attributed to the uniform dispersion of nanoplatelets in the polymer matrix and strong interfacial interactions between components.

TL;DR: In this article, a coordinated experimental and theoretical investigation into the evolution of the morphology of fluid-suspended graphene driven by an electric field, and the attainment of ultra-low percolation threshold in graphene-polymer nanocomposites was reported.

TL;DR: In this paper , a micro-mechanical model was developed to describe the electrical percolation and effective electrical conductivity of nanocomposites containing fillers with different shapes such as graphene nanoplatelets, carbon black, and carbon nanotubes.

TL;DR: In this article , two different graphene nanosheets with different oxygen groups' localization were synthesized to investigate their effect on the electrical properties of graphene/epoxy nanocomposite coatings.

TL;DR: The bottom-up chemical approach of tuning the graphene sheet properties provides a path to a broad new class of graphene-based materials and their use in a variety of applications.

TL;DR: In this article, the Berechnung der dielektrizitatatkonstanten and der Leitfahigkeiten fur Elektriatitat and Warme der Mischkorper aus isotropen Bestandteilen behandelt.

TL;DR: In this paper, a method of calculating the average internal stress in the matrix of a material containing inclusions with transformation strain is presented. But the authors do not consider the effects of the interaction among the inclusions and of the presence of the free boundary.

Abstract: Graphene is the name given to a two-dimensional sheet of sp2-hybridized carbon. Its extended honeycomb network is the basic building block of other important allotropes; it can be stacked to form 3D graphite, rolled to form 1D nanotubes, and wrapped to form 0D fullerenes. Long-range π-conjugation in graphene yields extraordinary thermal, mechanical, and electrical properties, which have long been the interest of many theoretical studies and more recently became an exciting area for experimentalists. While studies of graphite have included those utilizing fewer and fewer layers for some time,1 the field was delivered a jolt in 2004, when Geim and co-workers at Manchester University first isolated single-layer samples from graphite (see Figure 1).2 This led to an explosion of interest, in part because two-dimensional crystals were thought to be thermodynamically unstable at finite temperatures.3,4 Quasi-twodimensional films grown by molecular beam epitaxy (MBE) are stabilized by a supporting substrate, which often plays a significant role in growth and has an appreciable influence on electrical properties.5 In contrast, the mechanical exfoliation technique used by the Manchester group isolated the two-dimensional crystals from three-dimensional graphite. Resulting singleand few-layer flakes were pinned to the substrate by only van der Waals forces and could be made free-standing by etching away the substrate.6-9 This minimized any induced effects and allowed scientists to probe graphene’s intrinsic properties. The experimental isolation of single-layer graphene first and foremost yielded access to a large amount of interesting physics.10,11 Initial studies included observations of graphene’s ambipolar field effect,2 the quantum Hall effect at room temperature,12-17 measurements of extremely high carrier mobility,7,18-20 and even the first ever detection of single molecule adsorption events.21,22 These properties generated huge interest in the possible implementation of graphene in a myriad of devices. These include future generations of high-speed and radio frequency logic devices, thermally and electrically conductive reinforced composites, sensors, and transparent electrodes for displays and solar cells. Despite intense interest and continuing experimental success by device physicists, widespread implementation of graphene has yet to occur. This is primarily due to the difficulty of reliably producing high quality samples, especially in any scalable fashion.23 The challenge is really 2-fold because performance depends on both the number of layers present and the overall quality of the crystal lattice.19,24-26 So far, the original top-down approach of mechanical exfoliation has produced the highest quality samples, but the method is neither high throughput nor high-yield. In order to exfoliate a single sheet, van der Waals attraction between exactly the first and second layers must be overcome without disturbing any subsequent sheets. Therefore, a number of alternative approaches to obtaining single layers have been explored, a few of which have led to promising proof-ofconcept devices. Alternatives to mechanical exfoliation include primarily three general approaches: chemical efforts to exfoliate and stabilize individual sheets in solution,27-32 bottom-up methods to grow graphene directly from organic precursors,33-36 and attempts to catalyze growth in situ on a substrate.37-43 Each of these approaches has its drawbacks. For chemically derived graphene, complete exfoliation in solution so far requires extensive modification of the 2D crystal lattice, which degrades device performance.31,44 Alternatively, bottom-up techniques have yet to produce large and uniform † Department of Chemistry and Biochemistry and California NanoSystems Institute. ‡ Department of Materials Science and Engineering and California NanoSystems Institute. Chem. Rev. 2010, 110, 132–145 132