Structure tailorable triple-phase and pure double-polar-phase flexible IF-WS2@poly(vinylidene fluoride) nanocomposites with enhanced electrical and mechanical properties

A new low-cost high-permittivity flexible nanocomposite consisting of a polyvinylidene fluoride (PVDF) matrix and fullerene-like tungsten disulfide nanoparticle (IF-WS2 NP) filler was fabricated via a simple solution route. A comprehensive investigation by X-ray diffraction, attenuated total reflection-infrared spectroscopy, and differential scanning calorimetry (DSC) showed that 0.5–1 vol% of IF-WS2 induced a nonpolar α-phase to coexisting triple-phase transition in PVDF, whereas a slightly higher loading of 2 vol% induced pure double-polar β- and γ-phases. These results indicate that the structure and properties of the fabricated nanocomposite are easily tailorable. DSC during heating and cooling cycles and morphology observations further indicated that a polar phase was induced by the nucleation effect of the IF-WS2 NPs and electrostatic interactions. As a consequence of the multiphase coexistence and structure homogeneity, nanocomposites with approximately 0.5–1 vol% of IF-WS2 NPs showed enhanced dielectric and energy-storage performance as well as enhanced tensile strength and elongation. The new phase-tailorable nanocomposites with balanced properties are promising for applications as energy-storage capacitors, piezoelectric sensors, and other flexible multifunctional components. The results of this study will serve to deepen the understanding of the polymer polymorph and provide directions on new routes for fabrication of smart materials.