Polymer-Stabilized Graphene Dispersions At High Concentrations In Organic Solvents for Nanocomposite Production

Thursday, October 20, 2011: 1:48 PM
205 D (Minneapolis Convention Center)
Ahmed Wajid1, Sriya Das1, Fahmida Irin1, Tanvir Ahmed2, John Shelburne1 and Micah Green1, (1)Chemical Engineering, Texas Tech University, Lubbock, TX, (2)Mechanical Engineering, Texas Tech University, Lubbock, TX

Liquid phase exfoliation and dispersion of graphene, i.e. single layer graphite, is a critical challenge for bulk processing of graphene for use in advanced materials and devices.  We demonstrate a simple and effective dispersion of pristine (unfunctionalized) graphene at high concentrations in a wide range of organic solvents by use of a stabilizing polymer (polyvinylpyrrolidone, PVP). These polymer-stabilized graphene dispersions are shown to be aggregation-resistant and readily redispersible even after freeze-drying. These dispersions are then used as a strong and conductive nano-filler for polymer nanocomposites. In particular, PVP/graphene nanocomposites may be produced via in situ polymerization of vinyl pyrrolidone loaded with dispersed graphene, resulting in excellent load transfer and improved mechanical properties. Also, graphene-based epoxy nanocomposites with enhanced mechanical and electrical properties at a very low loading have also been achieved.  The electrical conductivity increases by 7 orders of magnitude and the tensile strength increases by 25 % in a 0.3 wt% graphene based epoxy nanocomposite compared to the baseline epoxy. Compared with the prior literature, we achieve higher concentrations and lower percolation threshold for our pristine graphene dispersions and composites, respectively.

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