Tuning the Mechanical Properties of Graphene Oxide Paper and Its Associated Polymer Nanocomposites by Controlling Cooperative Intersheet Hydrogen Bonding

Abstract

The mechanical properties of pristine graphene oxide paper and paper-like films of polyvinyl alcohol (PVA)-graphene oxide nanocomposite are investigated in a joint experimental-theoretical and computational study. In combination, these studies reveal a delicate relationship between the stiffness of these papers and the water content in their lamellar structures. ReaxFF-based molecular dynamics (MD) simulations elucidate the role of water molecules in modifying the mechanical properties of both pristine and nanocomposite graphene oxide papers, as bridge-forming water molecules between adjacent layers in the paper structure enhance stress transfer by means of a cooperative hydrogen-bonding network. For graphene oxide paper at an optimal concentration of ~5 wt % water, the degree of cooperative hydrogen bonding within the network comprising adjacent nanosheets and water molecules was found to optimally enhance the modulus of the paper without saturating the gallery space. Introducing PVA chains into the gallery space further enhances the cooperativity of this hydrogen-bonding network, in a manner similar to that found in natural biomaterials, resulting in increased stiffness of the composite. No optimal water concentration could be found for the PVA-graphene oxide nanocomposite papers, as dehydration of these structures continually enhances stiffness until a final water content of ~7 wt % (additional water cannot be removed from the system even after 12 h of annealing).

Hybridizing wood cellulose and graphene oxide toward high-performance fibers

“…A first-principles-based ReaxFF force field was developed and was able to account for various non-bonded interactions, including an explicit expression for hydrogen bonds. 22 In molecular dynamics models for GO sheets with and without NFC, the carbon atoms on the left and right end of the GO sheet were confined to only have the degree of freedom along the sliding direction. The vertical separation distance between the left ends or right ends was fixed to be 0.7 nm (about the typical inter-layer distance between GO sheets) for GO with NFC and 0.8 nm for GO without NFC.…”

Molecular Modeling and Mechanics of Acrylic Adhesives on a Graphene Substrate with Roughness

“…Graphene is naturally discovered in the form of graphite, which is known to have a weak interlayer interaction, and one cannot expect to produce a reliable composite by simply stacking them together [12]. Chemical methods including functionalizing the graphene by decorating chemical groups on the graphene surface can enhance the interfacial interaction by forming covalent bonds but will simultaneously change its mechanical and chemical property [13]. Referring to natural systems such as nacre interface and suture of the bone as shown in Fig.…”

Grain misorientation and grain-boundary rotation dependent mechanical properties in polycrystalline graphene

“…For example, graphene is used as the reinforce component in composite materials, and is also considered as an ultrathin yet elastically stretchable membrane for electronic devices and for biological applications . So far, the mechanical properties and deformation behaviour of pristine graphene or graphene with point defects have been intensively investigated Compton et al, 2012;Cranford et al, 2011;Koenig et al, 2011;Khare et al, 2007;Lee et al, 2008;Liu et al, 2007;Sen et al, 2010;Zhou and Huang, 2008;Zhang et al, 2006. Driven by the need for large-area graphene in engineering practice, polycrystalline graphene are broadly synthesized Li et al, 2009;Reina et al, 2009;Yu et al, 2011;Zhao et al, 2010).…”