Hydrophobic Fibrous Membranes with Tunable Porous Structure for Equilibrium of Breathable and Waterproof Performance

Breathable and waterproof membranes have great importance in various applications due to their permissibility of vapor transmitting and resistance to water penetrating. Despite the available strategies, it remains a serious challenge to fabricate membranes with best equilibrium of breathable and waterproof performance. Herein, hydrophobic fibrous membranes have been designed and prepared via electrospinning using polyurethane and fluorinated polyurethane as the raw polymers. By regulating the relative humidity and electrospinning time, fibrous membranes with tunable porous structure have obtained. Significantly, the effect of porosity, pore size, and pore length on the breathable and waterproof performance has been investigated. Ultimately, the fibrous membranes obtained at relative humidity of 60% with optimized porosity of 60%, mean pore size of 1.2 μm and pore length of 50 μm exhibit best equilibrium of breathable (water vapor transmission rate of 11.9 kg m −2 d −1 ) and waterproof (hydrostatic pressure of 86 kPa) performance, as well as good mechanical behavior with tensile strength of 10 MPa and elongation of 353%, indicating an appropriate candidate in various applications, especially for fabricating of protective garments.