Promising PVC/MXene based flexible thin film nanocomposites with excellent dielectric, thermal and mechanical properties

Abstract

Miniaturization of electronic gadgets continuously demands for the improved dielectric and flexible polymer composites. MXene flakes are considered as ideal electrically conductive 2D fillers inserted into the insulating polymer matrix to boost the dielectric performance of the polymer composites while maintaining superb flexibility. The present work is focused on the synthesis and characterization of strong and flexible PVC/MXene nanocomposites, possessing high dielectric constant and minimum energy loss, for their use in energy storage electronic applications. For this purpose, highly conductive delaminated MXene (DM) was prepared by HF-etching before delamination by DMSO and water and followed by high-temperature annealing. The prepared conducting DM was then inserted into insulating PVC in various concentrations by a simple solution casting method aided by strong sonication. The embedded DM in PVC facilitates the formation of conducting-insulating-conducting network CICN by increasing the AC conductivity of the obtained nanocomposites, which is explained according to the percolation theory. At the percolation threshold of 10 wt% MXene, the maximum number of PVC/MXene interfaces promotes interfacial polarization which endows the fabricated nanocomposites with high dielectric characteristics. The composite achieves a highest dielectric constant of 11800, which encompasses all the previous reported values. Also, low dielectric loss of 1.31 originates from the increase in electrical conductivity of the entire composite which in turn arises from the strong tunneling effect of conducting DM in PVC matrix. Moreover, thin films of the obtained composites also display very high flexibility, increased thermal conductivity of 3.48 W/mK, an extraordinary thermal stability (683.8°C) and good mechanical stability, as the tensile strength reaches to 174.08%. Afterwards, the respective optimized nanocomposites were characterized by SEM, XRD and FTIR convincing the strong interfacial interaction and improved dispersion of DM flakes into PVC matrix. These unique features of our prepared PVC/MXene flexible thin films support their tremendous potential for modern dielectric applications.