A comprehensive modeling of conductivity for copper nanowire polymer composites by interphase thickness and contact diameter

This work introduces an enhanced predictive model for the electrical conductivity of copper nanowire (CuNW)–reinforced composites. While the primary model of Deng and Zhang considers conventional parameters such as network fraction, filler volume content, and intrinsic filler conductivity, the proposed framework extends this approach by incorporating several critical, measurable, and previously neglected parameters, including the interphase region as an explicit third phase, nanowire contact diameter, matrix and nanowire surface tensions, nanowire waviness, and tunneling distance. As a result, the developed model demonstrates strong agreement with experimental measurements. Quantitative analysis shows that the nanowire aspect ratio is a key factor in the conductivity of samples, as the highest aspect ratio by filler radius of 7 nm and length of 24 μm yields a maximum conductivity of 18.9 S/m. Additionally, the highest nanocomposite conductivity of 7 S/m is achieved at the largest network fraction (0.5) combined with a minimal tunneling distance (2 nm). Interphase properties and contact geometry also affect charge transport, resulting in a peak conductivity of 3 S/m at the greatest interphase thickness of 10 nm and contact diameter of 47 nm. In contrast, nanocomposites with short or thick nanowires, large tunneling gaps and thin interphase layers may exhibit insulating behavior.