Multilayer Electrospun Fibers: Synergistic Integration of PLA and PVA/Chitosan/ZnO for Superior Water Resistance and Tensile Strength

Electrospun fibers have emerged as promising materials for diverse applications such as food packaging, protective clothing, wound dressing, biomedical devices, air and water filtration, and advanced coatings. However, their practical performance is often limited by poor mechanical strength, thermal stability, and water resistance. To address these challenges, a PVA/Chitosan/ZnO electrospun fiber mat was sandwiched between two polylactic acid (PLA) electrospun layers, forming a multilayer structure with enhanced tensile strength and hydrophobicity. X-ray diffraction (XRD) directly confirmed the incorporation of crystalline ZnO in the middle layer, while Fourier transform infrared spectroscopy (FTIR) indirectly supported this with the appearance of PLA-specific ester peaks and interaction bands in the 1000-1100 cm⁻¹ region. Scanning electron microscopy (SEM) revealed smooth, bead-free fibers with average diameters of 240±15 nm for the PVA/Chitosan/ZnO middle layer and 410±22 nm for the PLA/(PVA/Chitosan/ZnO)/PLA multilayer. The multilayer mats exhibited a contact angle of 126.13±0.48° and a tensile strength of 4.2 MPa, outperforming the single-layer PVA/Chitosan/ZnO (2.7 MPa) and pure PLA (1 MPa) fibers. These improvements result from a synergistic balance between the rigid, hydrophobic PLA outer layers and the flexible, ZnO-reinforced PVA/Chitosan inner core, effectively mitigating the brittleness of pure PLA. This multilayer design thus provides a high-performance, biocompatible material that integrates strength, flexibility, and moisture-barrier functionality, representing a promising candidate for sustainable packaging, protective coatings, and biomedical applications.