Engineered Poly(vinylidene fluoride) (PVDF)-Based Nanocomposites with Metal Ion (Al, Ag, Mg)-Doped Zinc Oxide (ZnO) Nanoparticles for Efficient Oil Sorption Application

Polyvinylidene fluoride (PVDF)/zinc oxide (ZnO) (doped with metal ions Al³⁺, Ag⁺, and Mg²⁺) nanocomposite films were fabricated by solution blending and compression molding techniques. Doping of metal ions in ZnO nanoparticles was confirmed by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM), and ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS) analyses. Solution-blended undoped and doped ZnO/PVDF nanocomposites showed a mix of electroactive γ and nonpolar α phases of PVDF, while compression-molded samples exhibited α phase, as confirmed by XRD and FTIR analyses. Compared to compression-molded films, solution-blended nanocomposite films exhibit a higher water contact angle (WCA), suggesting enhanced hydrophobicity mainly attributed to nanoscale surface roughness. Maximum WCA and surface roughness values of 115° and 215.5 ± 13.9 nm were obtained for a solution-blended 5 wt % Al-doped ZnO-incorporated nanocomposite film. To evaluate the sorption capacity and doping efficiency, immersion tests using gingelly and SAE 30 engine oils were conducted, which resulted in the highest oil sorption capacities of 165 and 310%, respectively, for 5 wt % Al-doped ZnO/PVDF films made by solution blending. Thus, this study reveals the significance of metal ion doping in ZnO affecting the hydrophobicity and oil sorption capacity of PVDF-ZnO nanocomposites and the effect of the processing route in influencing the hydrophobicity of nanocomposite films.