Environmentally friendly waterproof and breathable electrospun nanofiber membranes via post-heat treatment

Waterproof and breathable nanofiber membrane (WBM) is the core of the waterproof and breathable textile. At present, it is difficult to achieve simultaneous improvement of waterproofness, breathability and mechanical properties due to the limitation of material property and preparation technology. Herein, environmentally friendly and high-performing fluorine-free silicon-based polyurethane/polymethyl methacrylate/polyvinyl butyral (Si-PU/PMMA/PVB) WBMs were prepared via a facile electrospinning technology and post-heat treatment. By heating treatment, inter-fiber adhesion was achieved due to the melt of PVB, leading to a decrease in the maximum pore size of the fiber membrane, which enhances the waterproof ability. At the same time, the generated inter-fiber adhesion enhanced the interaction force between fibers, and thus improved the mechanical properties. The as-prepared PU/PMMA/PVB-40 WBM exhibits good water resistance with a hydrostatic pressure of 65.29 kPa, exceptional breathability with a water vapor transmission rate (WVTR) of 7.0 kg m−2 d−1, together with a high tensile strength of 11.52 MPa. The obtained Si-PU/PMMA/PVB WBMs have broad application prospects in special protective clothing and outdoor equipment.