Flexible electrospun KNN–MXene/PVDF–HFP composite nanofibers with enhanced dielectric properties for capacitive pressure sensing application

Abstract

The exploration of flexible ceramic–polymer nanocomposites with excellent dielectric and sensing properties has gained momentum due to their multifunctional characteristics and potential in the electronics industry. In the present work, electrospun nano-fibres based on KNN–MXene/PVDF–HFP composites were prepared, exhibiting improved dielectric permittivity (ε_r = 4.46 at 1 kHz for PM3) compared to pristine PVDF–HFP (ε_r = 2.31 at 1 kHz) at room temperature (∼27 °C). The structural and morphological properties of the prepared ceramics and the synthesised fibre composites were explored with X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and Raman spectroscopy. The dielectric properties of both ceramics and composite fibres have been extensively studied as a function of both frequency and temperature. The analysis revealed the improved conductivity and permittivity for the composite fibres. The stability of the ceramic fillers in the polymer was evaluated using spin–spin relaxation time (T₂) measurements. Next, the pressure-sensing of the prepared films was evaluated for sensor applications. The present investigation reports an enhancement in the sensing properties (2.7 times) of the 3% KNN–MXene/PVDF–HFP composite compared to pure PVDF–HFP.