Fluorine-free, Superhydrophobic Polyurethane and Stearic Acid Waterproof and Breathable Electrospun Nanofiber Membrane with Excellent Hydrostatic Pressure Resistance

High-performance waterproof and breathable nanofiber membranes are in urgent demand across various markets; however, their production typically relies on environmentally harmful fluorinated compounds or intricate manufacturing processes. In this study, we utilized fluorine-free polyurethane (PU) and stearic acid (SA) as raw materials, with dimethylformamide (DMF) employed as a pure, single solvent. A simple one-step electrospinning technique was applied to fabricate superhydrophobic PU/SA nanofiber membranes exhibiting exceptional waterproofness and breathability. This approach eliminates the need for hazardous fluorine-containing compounds while ensuring material stability through a pure solvent system and a streamlined one-step electrospinning process. Incorporating hydrophobic SA endows the PU/SA nanofiber membrane with a superhydrophobic nature, characterized by a water contact angle of 150°. By systematically optimizing the SA content within the PU/SA nanofiber membranes, the resulting membrane exhibits remarkable waterproofness, with an ultrahigh hydrostatic pressure resistance of 102.57 kPa, alongside excellent breathability, as indicated by a water vapor transmission (WVT) rate of 5.034 kg m-2 d-1. The PU/SA nanofiber membrane also has good air permeability (22.06 mm s-1) and robust mechanical properties, including a tensile strength of 7.17 MPa and an elongation at break of 74.80%. Moreover, the PU/SA nanofiber membrane demonstrates excellent antifouling and self-cleaning properties. The PU/SA nanofiber membrane developed in this study, with its superior waterproof and breathable performance, holds significant potential for applications in outdoor apparel.