Thermally induced chemical cross-linking reinforced fluorinated polyurethane/polyacrylonitrile/polyvinyl butyral nanofibers for waterproof-breathable application

Electrospun nanofibrous membranes with thin fiber diameter, small pore size, and high porosity have attracted a great deal of attention in the waterproof and breathable field. However, great challenges still remain in simultaneously reinforcing the mechanical and waterproof-breathable performance of such materials. In this study, a new type of fluorinated polyurethane/polyacrylonitrile/polyvinyl butyral nanofibrous membranes (FPU/PAN/PVB NFM) with a blocked isocyanate prepolymer (BIP) as chemical cross-linking agent were fabricated. The composite NFM, with robust mechanical, waterproof and breathable performance, has been prepared using an innovation strategy combining electrospinning with thermally induced physical bonding and chemical cross-linking. By systematically tuning the cross-linked temperature and time as well as the concentration of PVB and BIP, large breaking elongation (81.5%), good hydrostatic pressure (110 kPa) and modest WVTR (9.6 kg m −2 d −1 ) of the membranes were achieved. Meanwhile, the physically bonded structure and chemically cross-linked networks between PVB and BIP endowed the composite NFM with the robust tensile strength of 32.8 MPa, which was three times higher than that of pristine FPU/PAN membranes. Considering the excellent performance of the as-prepared membranes, this simple and intriguing approach may provide a versatile platform for exploring the applications of the bonded and cross-linked membranes in separation processes, membrane distillation, self-cleaning materials, and protective clothing.