Carbon Nanotube and Copper Nanowire Polymer Nanocomposites for Electromagnetic Shielding and Charge Storage Applications

Polymer nanocomposites have unique multifunctional properties resulting from the size and shape of the fillers and display superior electrical, thermal and mechanical properties to conventional polymer composites due to the nanoscale size of the filler. We have synthesized Copper and Silver nanowires using an aluminum oxide template based electro-deposition technique, and the nanowires were melt-mixed with polymers via solution mixing and in miniature mixers, and electrical and mechanical properties were tested. The electrical, mechanical and rheological properties of these new materials were studied and evaluated for industrial applications such as personal electronics enclosures, shielding for aerospace, batteries and anti-static packaging. The morphology of the polymer nanocomposites was characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) and revealed a unique honeycomb structure (segregated network structure) that helped to significantly lower the electrical percolation threshold and increase electromagnetic shielding properties for applications such as cell phone and laptop enclosures. Hybrid filler systems of Cu nanowire and carbon nanotubes in PS indicated that there is an optimum nanofiller ratio for best electrical properties. Hybrid nanocomposites or MWCNT and Copper Nanowires (CuNW) displayed extremely low electrical percolation thresholds lower than 0.0005 volume fraction. The EMI shielding for these hybrid metal nanowire-polymer composites is among the highest reported for nanocomposites. The outstanding performance of these materials in X-band also opens up opportunities for security and military applications. By controlling the surface electrical properties of the filler, we found that there is an excellent opportunity to use these materials for charge storage applications by tuning the permittivity and dissipation factor.