Flexible carbon nanocomposite fabric with negative permittivity property prepared by electrostatic spinning

Negative permittivity materials hold immense potential in the field of sensing due to their high sensitivity. As the next generation of sensors moves toward flexible and wearable designs, conventional negative permittivity materials, which are predominantly based on rigid metal conductive networks, struggle to achieve the necessary flexibility. In this study, we synthesized Ni_x/C/SiO₂ flexible composite films by electrospinning and high-temperature pyrolysis. Using polyacrylonitrile (PAN) as the precursor, along with nickel acetate tetrahydrate and tetraethyl orthosilicate, the material underwent carbonization to form a dual-phase carbon-nickel network, establishing a flexible conductive framework. A relatively low carbonization temperature was employed to maintain the flexibility of the carbon network, avoiding excessive graphitization that could compromise flexibility. To ensure sufficient carrier concentration within the system, Ni was introduced, while the addition of SiO₂ not only enhanced the flexibility of the composite fiber membrane but also strengthened the positive permittivity effect, allowing for precise tuning of the negative permittivity. The composite films exhibit excellent negative dielectric properties of about − 2000 and conductivity up to 0.018 (Ω·cm)⁻¹. Our research offers a viable approach for introducing flexibility into negative permittivity materials, thereby advancing their potential applications in the sensing field.