(87d) Graphene Sheets-Oil Nanocomposites: Equilibrium and Transport Properties From Molecular Simulation
AIChE Annual Meeting
2010 Annual Meeting
Materials Engineering and Sciences Division
Monday, November 8, 2010 - 1:45pm to 2:10pm
Nanostructured materials hold unrestricted promises in material sciences. It has long been thought that dispersing nanoparticles in a polymer blend can enhance both mechanical and transport properties. It would be for example desirable to generate a polymer nanocomposite with high thermal conductivity. Such materials could be obtained by dispersing thermally conductive nanoparticles within polymers. Carbon-based nanoparticles are extremely promising towards these goals, although the use of carbon nanotubes is hindered by high resistance to heat transfer from the nanotubes to the polymer matrix. We are interested in composites in which graphene sheets (GS) are dispersed within organic oils. Although pristine GS agglomerate when dispersed in oils such as octane, hexane and dodecane, our equilibrium molecular dynamic simulations demonstrate that when the GS are functionalized with short branched hydrocarbons, they remain well dispersed within the oils. We are now conducting equilibrium and non-equilibrium molecular dynamics simulations to assess the effective interactions between GS dispersed in oils, the self-assembly of GS within oils, the structure of the fluid surrounding the GS, and the heat transfer from a GS to the surrounding matrix. Our tools are designed to understand the effect of GS size, oils molecular weight and molecular architecture on the GS dispersability and GS-oil heat transfer rate. For example, we detail the formation of nematic phases for grapheme sheets in oils at room conditions as a function of the grapheme volume fraction. As expected, the transition from isotropic to nematic phase occurs at lower grapheme sheet concentrations as the grapheme sheet size increases. As a consequence of the anisotropic molecular-level structure, a number of macroscopic properties show anisotropic behavior. We will discuss here our results, obtained conducting non-equilibrium molecular simulations and macroscopic modeling, for heat conductivity predicted for graphene-based nanocomposites.