EAGER: The Verge of Percolation in Nanoparticle Networks

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This EArly-concept Grant for Exploratory Research (EAGER) award provides funding to evaluate the feasibility of producing graded nanocomposites with controlled linear nanofiller concentration profiles. Experimental research aims focus on a custom processing technique where dual ramped-flowrate pumps, a static mixer, and rapid curing are used to create nanofiller-loaded polymer composites with a constant gradient in reinforcement. The concentration profile will be measured by light absorbance in samples taken from the composite precursor prior to curing. The conductivity profile will be tested pointwise using a four-point probe after curing. The desired nanofiller is pristine graphene, a nanomaterial prized for its outstanding combination of transport properties. Polymer matrices to be explored include Polydimethylsiloxane and epoxy. Because the graphene sheets are conductive, it is hypothesized that the axial conductivity profile mimics percolation scaling laws such that gradient composites may be used to investigate how percolation threshold and critical scaling exponent are affected by varying dispersion quality, nanofiller geometry, and nanofiller size as a function of sonication. If successful, this project will provide nanoscale insight (into percolating network architecture) and contribute to advanced material functionality (in sensing applications in the aerospace and energy industry). The composites produced by this technique will allow for high-accuracy, high-repeatability comparative studies of nanofiller percolation within polymer matrices. Such composites have immediate application to a range of engineering needs, particularly in next-generation piezoresistive smart materials. Broad scientific communities affected by this exploratory work include those interested in nanomaterial exfoliation and dispersion, composite manufacture, percolation theory, and nanomaterial electrical contacts and networks.