Eco-friendly fabrication of hydrophobic and breathable nanofibrous membranes via molecularly engineered WPU/PAM composites

Abstract

As demands increase for multifunctional textiles and breathable coatings in high-humidity and high-mobility environments, the development of membranes that combine waterproofing, breathability, and mechanical durability has become a critical challenge. This study presents a novel, organic solvent-free electrospinning approach to fabricate waterborne polyurethane (WPU)-based nanofiber membranes, enhanced by polyacrylamide (PAM) as a dual-functional additive. By leveraging hydrogen bonding interactions between the –COO⁻, –NHCOO– groups in WPU and the –CONH₂ groups in PAM, the resulting composite achieved stable electrospinning, improved fiber morphology, and a significantly higher water contact angle (86.9°), compared to conventional WPU/PVA systems (<10°). The optimized WPU/PAM-3 membrane maintained high air permeability and excellent tensile strength, while also showing low water absorption (∼18%) and strong structural stability under thermal, mechanical, and environmental cycling. Structural analyses via FTIR, XRD, and XPS confirmed enhanced interfacial compatibility and molecular interaction. Notably, this work eliminates the need for volatile organic solvents and hygroscopic additives like PVA, solving common limitations in traditional WPU systems. The resulting membrane offers a sustainable, high-performance solution for protective textiles, medical materials, and flexible barrier coatings, marking a significant advancement in eco-friendly, breathable membrane technology.