Article

Elastic Properties of Chemically Derived Single Graphene Sheets

Max-Planck-Institut fur Festkorperforschung, Heisenbergstrasse 1, 70569 Stuttgart, Germany.
Nano Letters (Impact Factor: 13.59). 08/2008; 8(7):2045-9. DOI: 10.1021/nl801384y
Source: PubMed

ABSTRACT

The elastic modulus of freely suspended graphene monolayers, obtained via chemical reduction of graphene oxide, was determined through tip-induced deformation experiments. Despite their defect content, the single sheets exhibit an extraordinary stiffness ( E = 0.25 TPa) approaching that of pristine graphene, as well as a high flexibility which enables them to bend easily in their elastic regime. Built-in tensions are found to be significantly lower compared to mechanically exfoliated graphene. The high resilience of the sheets is demonstrated by their unaltered electrical conductivity after multiple deformations. The electrical conductivity of the sheets scales inversely with the elastic modulus, pointing toward a 2-fold role of the oxygen bridges, that is, to impart a bond reinforcement while at the same time impeding the charge transport.

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    • "The unique structure of graphene holds great promise in potential applications which includes nanoelectronics, sensors , batteries, supercapacitors, hydrogen storage and nanocomposites[1], Young's modulus (1 TPa), fracture strength (130 GPa) and the thermal and electrical conductivity of 5 W mK À1 and 720 S m À1 respectively[2,3]. Great efforts have been made in preparation of highly conducting composites using the solution-processed graphene for transparent electrodes4567and photovoltaic device applications[8,9]. Bulk quantities of graphene can be produced by the chemical reduction of graphene oxide (GO) using graphite as a precursor material[10]. "
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    ABSTRACT: A novel ultra-high-k composite material comprising of polyvinyl alcohol (PVA) as a polymer matrix and vanadium pentoxide (V2O5) and graphene oxide (GO) as fillers have been developed successfully using colloidal processing technique. The PVA/V2O5 and PVA/V2O5/GO composites were characterized using Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, UV-vis spectroscopy (UV), X-ray diffraction (XRD), thermogravimetric analysis (TGA), polarized optical microscopy (POM), Scanning electron microscopy (SEM) and atomic force microscopy (AFM). FTIR studies indicate the strong chemical interaction between GO and polymer matrix. SEM results confirm that GO was homogeneously dispersed within the polymer matrix. The dielectric measurements show that PVA/V2O5/GO composites exhibit ultra-high dielectric constant and low dielectric loss. The dielectric constant increases from (ε = 189.40, 50 Hz, 40°C) for PVA/V2O5 (95/05) composites to (ε = 5610.76, 50 Hz, 50°C) for PVA/V2O5/GO composites with 2.5 wt% GO loading and the dielectric loss increases from (tan δ = 3.76, 50 Hz, 80°C) for PVA/V2O5 (95/05) composites to (tan δ = 9.77, 50 Hz, 150°C) for PVA/V2O5/GO composites with 2.5 wt% GO loading. This study opens up the avenue to prepare novel graphene-based polymer composites having ultra-high dielectric constant and low dielectric loss and extends the application window of graphene based fillers.
    Full-text · Article · Jan 2016 · European Polymer Journal
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    • "This EMI shielding application of graphene paper is related to its low density, excellent flexibility and extraordinary electrical properties of graphene materials [20] [21] [22] [23]. Graphene paper [16] prepared by using graphene oxide (GO) as a template for synthesis and processing showed good mechanical properties with a breaking stress at 120 MPa. "
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    ABSTRACT: Syntheses of multifunctional structures, both in two-dimensional and three-dimensional space, are essential for advanced graphene applications. A variety of graphene-based materials has been reported in recent years, but combining their excellent mechanical and electrical properties in a bulk form has not been entirely achieved. Here, we report the creation of novel graphene structures such as graphene pellet and graphene paper. Graphene pellet is synthesized by chemical vapor deposition (CVD), using inexpensive nickel powder as a catalyst. Graphene pellet can be further processed into a graphene paper by pressing. The latter possesses high electrical conductivity of up to 1136 ± 32 S cm−1 and exhibits a breaking stress at 22 ± 1.4 MPa. Further, this paper-like material with thickness of 50 μm revealed 60 dB electromagnetic interference (EMI) shielding effectiveness
    Full-text · Article · Feb 2015 · Carbon
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    • "In comparison to graphene, however, experimental investigations of the mechanical properties of monolayer GO are limited, despite widespread implementation of GO films as a stiffening and strengthening additive in composite applications [15] [16]. The 3D elastic modulus of monolayer GO membranes has been experimentally characterized and is reported to be approximately $25% of pristine graphene [17] [18]; however , the strength of monolayer GO has not been experimentally measured to date [19]. Computational studies have predicted that the strength of monolayer GO could be as high as approximately 50% of the intrinsic strength of pristine graphene [20] [21]. "
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    ABSTRACT: In this study, the strength of monolayer graphene oxide membranes was experimentally characterized. The monolayer GO membranes were found to have a high carbon-to-oxygen ratio (similar to 4:1) and an average strength of 17.3 N/m (24.7 GPa). This measured strength is orders of magnitude higher than previously reported values for graphene oxide paper and is approximately 50% of the 2D intrinsic strength of pristine graphene. In order to corroborate strength measurements, experimental values were compared to theoretical first-principles calculations. Using a supercell constructed from experimental measurements of monolayer graphene oxide chemistry and functional structure, density functional theory calculations predicted a theoretical strength of 21.9 N/m (31.3 GPa) under equibiaxial tension, in good agreement with the experimental data. Furthermore, computational simulations were used to understand the underlying fracture mechanism, in which bond cleavage occurred along a path connecting oxygenated carbon atoms in the basal plane. This work shows that monolayer graphene oxide possesses near-theoretical strength reaching tens of GPa.
    Full-text · Article · Jan 2015 · Carbon
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