Critical Percolation of SWNT-IL-Epoxy Composites Synthesized by a Streamlined Process

1-ethyl-3-methylimidazolium dicyanamide is a room temperature ionic liquid that interacts with SWNTs through weak Van der Waals interactions to disrupt bundles while concurrently initiating an anionic polymerization with the epoxy matrix, creating a thermosetting composite system. The small particle size of SWNT minimizes disruption of the polymer matrix, while high surface area increases the interactions between the polymer and the SWNTs. Tube dispersion is monitored by electrical conductivity measurements, conductivity and filler loading are related by a power law equation and compared to theoretical percolation. The resulting composite system shows an exponential increase in conductivity with increasing filler loading and an ultralow critical percolation of 4.29x10^-5 volume fraction. Experimental deviation from theoretical percolation is illustrated by SEM imaging, revealing a fracture surface with dispersed SWNTs and small areas of SWNT agglomerations. This non-volatile solvent process creates nanocomposites with simplified processing and improved interfacial interactions. The nanocomposite enables control of desired material properties including mechanical, thermal and electrical by varying parameters such as particle size, surface area of the nanoparticle and the strength of the interfaces.