Synergistic Mixing Effects on Electrical and Mechanical Properties in Homogeneous CNT/Cu Composites

A homogeneous composite of aligned carbon nanotubes (CNTs) and copper was fabricated by combining copper nanoparticle functionalization with the CNT dry-spinning technology. The copper nanoparticles decorating the CNTs enabled high-yield copper electroplating inside the CNT yarn. Our homogeneous CNT/Cu composite had a weight density 38% lower than copper, yet had a 2.8-fold lower-temperature coefficient of resistance (TCR), 3.6 times higher specific current capacity (ampacity), and almost the same specific conductivity. The high alignment of the CNTs and the firm contacts at the CNT/Cu interface contributed to maximizing the conductivity by inducing elastic scattering of free electrons, leading to lower TCR and higher specific ampacity. The firm contacts at the CNT/Cu interface also enabled effective load transfer between the CNTs and copper matrix and reinforced the tensile strength of copper by a factor of 3.7. The smaller TCR and reinforced tensile properties of the homogeneous CNT/Cu composite make it promising for thin, lightweight wiring materials for small, lightweight motors and coils.