Multilevel porous structured polyvinylidene fluoride/polyurethane fibrous membranes for ultrahigh waterproof and breathable application. (December 2017) - Cui, Hongmin
Abstract: Porous membranes that can resist water droplet and transmit water vapor simultaneously have aroused wide attention due to their promising application in individual protection. However, the fabrication of such materials remains a challenge. Here we fabricated electrospun fibrous membranes exhibiting ultrahigh waterproofness and excellent breathable performance simultaneously by constructing a multilevel porous structure. The careful control over the concentration of polyvinylidene fluoride (PVDF) generated improved hydrostatic pressure and water vapor transmitting rate (WVTR). More importantly, by coupling polyurethane/fluorinated (PU/FPU) membrane with PVDF membrane layer by layer, the resultant composite PVDF/PU membrane presented ultrahigh hydrostatic pressure (140 kPa) and WVTR (11.3 kg m -2 d -1 ). We unveiled that this excellent waterproof/breathable performance was achieved benefitting from the differentiated pore size and porosity of the two membranes. The creation of such an encouraging membrane could establish a new optimization methodology for waterproof/breathable membranes. Graphical abstract: Highlights: The hydrophobic surface was constructed using environmental friendly raw materials rather than conventional fluorinated polyurethane with notorious long fluorocarbon chain. The multilevel porous structure was designed by taking advantage of differentiated pore size and porosity of PVDF and PU/FPU membranes. The resultant composite PVDF/PU membrane presented ultrahigh hydrostatic pressure (140 kPa) and water vapor transmission rate (11.3 kg m -2 d -1 ), which was unreachable for the existing materials.