Elastic Properties of Chemically Derived Single Graphene Sheets

ArticleinNano Letters 8(7):2045-9 · August 2008with34 Reads
DOI: 10.1021/nl801384y · Source: PubMed
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.
    • "In addition, the mechanical properties of 2D materials largely depend on the density of crystal defects and thus are related to the preparation methods. For instance, the larger number of vacancy defects in the GO-reduced graphene and the existence of voids at the grain boundaries, together with wrinkles in polycrystalline graphene prepared by the CVD method, can contribute to the weaker mechanical properties [4, 55]. In addition, the presence of a larger number of grain boundaries can affect the Young's modulus of 2D materials negatively [56]. "
    [Show abstract] [Hide abstract] ABSTRACT: Two-dimensional (2D) materials have attracted increasing attention recently due to their extraordinarily different material properties compared with conventional bulk materials. The 2D materials possess ultralow weight, high Young’s modulus, high strength, outstanding carrier mobility, as well as high anisotropy between the in-plane and out-of-plane mechanical properties. The nearby atoms in the same plane of layered 2D materials are connected via covalent bonding, while the interlayers are stacked together via weak van der Waals interactions. In this article, we review the in-plane mechanical properties (including the in-plane Young’s modulus, pretension, breaking strength/strain) and out-of-plane mechanical properties (including the perpendicular-to-plane Young’s modulus, shear force constant, and shear strength) of different 2D materials, varying from conductors, semiconductors, to insulators. The different fabrication methods for suspended 2D material structures are presented. The experimental methods and principles for mechanical properties characterization are reviewed. A comparison of the mechanical properties among different 2D materials is summarized. Furthermore, electrical output change as a result of mechanical deformation (piezoresistive and piezoelectric effects) is introduced briefly. By exploiting the unique mechanical and mechanoelectric transduction properties, 2D materials can be used in wide-ranging applications, including flexible electronics, strain sensors, nanogenerators, and innovative nanoelectromechanical systems (NEMS).
    Full-text · Chapter · Aug 2016 · Journal of Colloid and Interface Science
    • "Here, v m , and v p are the matrix and particle Poisson ratios, and constants A, A 3 , A 4 , A 5 are calculated from matrix/particle properties and components of the Eshelby tensor [72,73], which depend on the particle A f , and dimensionless elastic constants of the matrix . For modeling, we used E p as 250 GPa for TRG sheets [74,75], v p as 0.0006 [76], v m as 0.48 for PE [77], whereas the experimentally determined E m values are used throughout. The only variable fitting parameter in the two models is the particle aspect ratio (A f ). "
    [Show abstract] [Hide abstract] ABSTRACT: Poor dispersion of graphene in non-polar polymer matrices creates composites with limited applications. A method to improve the dispersion of graphene in polyethylene (PE) via blending PE with oxidized PE (OPE) is examined. Graphene was produced by simultaneous thermal exfoliation and reduction of graphite oxide. Nanocomposites of graphene with PE as well as graphene with PE/OPE-blends were prepared by solvent blending. Improved dispersion of graphene in PE/OPE blends substantially decreases percolation from both rheological (0.3 vol%) and electrical (0.13 vol%) measurements compared to neat PE nanocomposites (1 and 0.29 vol%), respectively. A universal Brownian dispersion of graphene in polymers was concluded similar to that of nanotubes, following the Doi-Edwards theory. Micromechanical models, such as Mori-Tanaka and Halpin-Tsai models, modeled the mechanical properties of the nanocomposites. The nanocomposites microstructure, studied by small angle x-ray scattering, confirmed better dispersion of graphene at lower loadings and the formation of surface fractals in the blend/graphene nanocomposites; whereas only mass fractals were observed in neat PE/graphene nanocomposites.
    Full-text · Article · Jun 2016
    • "Since its discovery by Geim and Novoselov [1] , the sp 2 hybridized 2D carbon-network, graphene has attracted a great deal of attention due to its outstanding properties such as defined optical transparency [2,3], extraordinary mechanical strength [3,4] and high electrical conductivity [5] . Hence, in the field of nanocomposites with inorganic nanoparticles graphene is a very attractive component as a wrapping material [6,7] whereby these nanocomposites can be used in sensors [8,9], catalysis [10][11][12]or for energy storage materials [13][14][15][16] . "
    [Show abstract] [Hide abstract] ABSTRACT: In our present work we developed a novel graphene wrapping approach of Ni@Fe2O3 superparticles, which can be extended as a concept approach for other nanomaterials as well. It uses sulfonated reduced graphene oxide, but avoids thermal treatments and use of toxic agents like hydrazine for its reduction. The modification of graphene oxide is achieved by the introduction of sulfate groups accompanied with reduction and elimination reactions, due to the treatment with oleum. The successful wrapping of nanoparticles is proven by energy dispersive X-ray spectroscopy, high-resolution transmission electron microscopy and Raman spectroscopy. The developed composite material shows strongly improved performance as anode material in lithium-ion batteries (compared to unwrapped Ni@Fe2O3) as it offers a reversible capacity of 1051 mAh g-1 after 40 cycles at C/20, compared with 460 mAh g-1 for unwrapped Ni@Fe2O3. The C rate capability is also improved by the wrapping approach, as specific capacities for wrapped particles are about twice of those offered by unwrapped particles. Additionally, the benefit for the use of the advanced superparticle morphology is demonstrated by comparing wrapped Ni@Fe2O3 particles with wrapped Fe2O3 nanorice.
    Full-text · Article · Jun 2016
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