Effect of elastic modulus mismatch of epoxy/titanium dioxide coated silver nanowire composites on the performance of thermal conductivity

The effect of elastic modulus mismatch of epoxy/silver nanowires (epoxy/AgNWs) composites on thermal conductivity was critically evaluated by synthesizing a stiff titanium dioxide (TiO2) coating on the surface of AgNWs (designated as AgNWs@TiO2) with different length/diameter aspect ratio. Compared to epoxy/AgNWs composites, AgNWs@TiO2 could be more uniformly dispersed in epoxy matrix. However, the TiO2 intermediate layer with a higher elastic modulus increased the modulus mismatch with epoxy, exacerbating the interfacial phonon scattering, and the thermal conductivity of the epoxy/AgNWs@TiO2 composites was decreased. Moreover, the epoxy/AgNWs@TiO2 composites possessed enhanced volume electrical resistivity and reduced dielectric properties relative to the epoxy/AgNWs composites. These observed results on thermal conductivity, electrical insulation, dielectric loss and dielectric constant due to TiO2-coated AgNWs are more prominently displayed at higher nanowire loading (4 vol%) and aspect ratio (1000).