Mathematical mechanism of gradient voltage-driven hierarchical PVA nanofibers morphology and property synergy

Source abstract

Inspired by the hierarchical structure of spider silk, continuous hierarchical poly­vinyl alcohol nanofiber membranes were fabricated via electrospinning with gradient voltage regulation (10-25 kV ascending and 25-10 kV descending), while other spinning parameters were kept constant. A systematic investigation was conducted to examine the impact of the gradient voltage-driven hierarchical structure on the morphology, mechanical properties, and air permeability (a pivotal mass transfer property) of nanofibers. This investigation was coupled with mathematical mechanism analysis utilizing the multi-defect cascade model and Gibson-Ashby surface softening relationship. Scanning electron microscopy and diameter distribution analysis revealed that the hierarchical nanofibers exhibited moderate diameters, eliminated bead defects caused by low voltage, and achieved higher uniformity compared to nanofibers prepared at a single voltage. Tensile tests demonstrated that the breaking strength of hierarchical nanofibers was balanced at an intermediate level, benefiting from the synergistic effect of fibers with different strength contributions. Air permeability tests (conducted on aluminum foil and non-woven fabric substrates) demonstrated that the hierarchical structure achieved a synergistic balance between mechanical properties and air permeability, thereby overcoming the trade-off between fiber fineness and permeability in single-voltage electrospinning. This work presents a straightforward gradient voltage regulation strategy for the preparation of hierarchical nanofibers, which exhibit optimized comprehensive performance. The mathematical mechanism analysis provides theoretical support for the structure-performance regulation of electrospun nanofibers, making them promising for applications involving mass transfer and mechanical load-bearing (e.g., air filtration, functional membranes).