Polymer nanofibre composite nonwovens with metal-like electrical conductivity

Bendable and breathable polymer nanofibre nonwovens with metal-like electrical conductivity are required for lightweight electrodes and electric shielding design with applications in batteries, functional textiles, sensors, cars, aerospace, constructions, mobile phones, and medical devices. Metal-like conductivity in polymer nonwovens has not been achieved till now due to the limitation of the existing processing techniques. We show here, the metal-like electrical conductivity of 750,000 S/m in polyacrylonitrile (PAN), poly(epsilon -caprolactone) (PCL) nonwoven using very low content of silver nanowires (AgNW; 3.35vol%). The key to the high conductivity was the homogenous distribution of AgNW in nonwoven made by wet-laid process using short electrospun fibre and AgNW dispersion. Above a threshold of 0.36vol% AgNW, the conductivity of the nonwoven increased by seven orders of magnitude, which we attribute to the onset of percolation of the AgNW. Our nonwoven-AgNW composites show fast heating and cooling within a few seconds at a voltage of 1.1V, which is in the range of portable devices. These composites are also breathable and bendable. The electrical conductivity was independent of the bending angle of the composite, which is important for applications mentioned above and would help other scientists to design new conductive materials in the future. Conductive composites: Polymer nanofibre composite rivals metalNew method has enabled preparation of polymer-metal composite nonwovens with very low metal loading but metal-like high conductivity. A collaborative team led by Andreas Greiner from University of Bayreuth, Germany demonstrates that by reducing the percolation threshold significantly with a wet-laid method, silver nanowire and polymer composite nonwovens show high electrical conductivity of 750.000S/m at only 3.4vol% loading of silver. It can be attributed to the homogenous distribution of the silver nanowires in the electrospun polymer fibres. In addition, the high conductivity of the composites is almost fully resistive to bending. These nice features enable the use of the conductive composite nonwovens in various flexible, lightweight and economic applications, such as portable Joule heaters with very low operating voltages of only 1.1V.