Abstract
The incorporation of conductive nanofillers into an insulating polymer matrix commonly leads to nanocomposites with good electrical, thermal, and mechanical properties. In this study, copper nanowires (CuNWs) and polystyrene (PS) microspheres were synthesized along with the fabrication of CuNW/PS polymer nanocomposites. The electrical, thermal, mechanical, rheological, and morphological properties of the CuNW/PS nanocomposites were examined. The CuNWs were homogeneously dispersed in the PS matrix through latex blending. For the CuNW/PS nanocomposites, the storage modulus was higher than the loss modulus at all frequencies, indicating their elastic-dominant behavior. The electrical and thermal conductivities of the nanocomposites increased with an increasing CuNW content. Using a mixed dispersion of two monodisperse PS particles of 500 nm and 5 μm in diameter resulted in the highest electrical conductivity (ca. 10° S/m for 30 wt % nanofillers) among the nanocomposites. In addition, the introduction of silica- and polydopamine-coated CuNWs as nanofillers imparted insulation properties to the nanocomposites, with electrical conductivities to 10-10-10-8 S/m. When using 500 nm PS particles, the thermal conductivity of the surface-modified CuNW/PS nanocomposite at 30 wt % of CuNW was enhanced to 0.22 W/m·K compared to 0.17 W/m·K for its unmodified counterpart. We have achieved multiple innovative approaches, including the use of mixed particle sizes, surface modification of CuNW, and the exploration of elastic-dominant behavior. This enhanced thermal conductivity, coupled with the attainment of insulation properties, presents a distinct advantage for thermal interface material (TIM) applications.