Hydrophobic PVDF/clay fibrous nanocomposites prepared by solution blow spinning with tunable mechanical properties

Poly(vinylidene fluoride) (PVDF)/clay fibrous composites were produced by Solution Blow Spinning (SBS) in order to investigate the structural, morphological, thermal, mechanical, and wettability limits of this high-productivity technique when applied to polymer nanocomposites with high inorganic loadings. Montmorillonite clay was incorporated at 3, 5, 10, 20, and 30 wt% relative to the polymer content. The composites were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), tensile testing, and contact angle measurements. SBS enabled the formation of self-supported micro- and nanofibrous composites with average fiber diameters below 200 nm. Increasing clay content significantly affected solution viscosity, fiber morphology, composite thickness, and mechanical performance, revealing practical processing limits of the technique. SEM and EDX analyses confirmed clay incorporation and dispersion, although agglomeration became prominent at loadings above 10 wt%. XRD results showed the coexistence of α and β crystalline phases of PVDF, which were not altered by clay addition. Thermal analysis indicated that clay acted as a catalytic agent for PVDF degradation, reducing thermal stability at higher filler contents. Mechanical tests revealed an increase in stiffness and tensile strength at low clay concentrations, followed by a pronounced deterioration at higher loadings due to morphological heterogeneities. Wettability analyses showed that all composites remained hydrophobic, with contact angle values increasing with surface roughness and clay content. These results demonstrate that Solution Blow Spinning is a viable and scalable route for producing PVDF-based fibrous nanocomposite composites, while also establishing critical composition and morphology thresholds that must be considered for functional applications.