Facile and Efficient Negative Permittivity Realization of Copper Microwire Polymer Metacomposites at X-Band Frequency

Negative permittivity is a unique and fascinating property which is essential for applications such as for a perfect lens and 100% electromagnetic wave absorption. Both positive and negative real permittivity are effectively modulated by commercially available low-cost copper microwire epoxy metacomposites. The influence of diameter and length of the copper wire and weight percentage in the polymer composite on the dielectric properties are investigated. Relative real permittivity of 3–240 was obtained in X-band frequency (8.2–12.4 GHz) by controlling the composition of the composites. Ultraweak relative negative permittivity of -5-0 is present for samples of Cu-2mm-70 wt.%/epoxy (EP) or Cu-5mm-50 wt.%/EP composites owing to the low-frequency plasmonic state of free electrons in the percolated networks. The as-prepared Cu/EP composites are promising for microwave manipulating metamaterials and related high-frequency devices. Graphical Abstract