Magnetic field-induced alignment of nickel-coated copper nanowires in epoxy composites for highly thermal conductivity with low filler loading

In this work, the large-scale produced copper nanowires (Cu NWs) were coated by nickel nanoparticles (Ni NPs) lay, i.e., Cu [email protected] And under external magnetic field condition, Cu [email protected] as thermally conductive fillers were filled into epoxy (EP) resin to prepare the composites with high thermal conductivity (TC). The results showed that, when the magnetic field was 80 mT, Cu [email protected] (molar ratio of Cu:Ni = 10:5, and saturation magnetization (Ms) = 20.3 emu/g) can distribute in EP resin in an orderly manner along the direction of the magnetic field, endowing the composite with excellent TC at lower loading. Especially, when only 9 vol% Cu [email protected] was filled, the TC along the direction of the magnetic field can reach 2.90 W/mK, which was 12.81 times than that of neat EP resin. Even so, the composite still maintained outstanding insulation properties, namely, the volume resistivity and the dielectric strength were 1.79 × 1015 Ω cm and 12.88 kV/mm, respectively. In addition, compared to that of neat EP resin, the composite still possessed splendid heat stability and mechanical properties. For the above positive improvement, the corresponding mechanisms were also discussed in detail.