Hydrophobic polyvinylidene fluoride fibrous membranes with simultaneously water/windproof and breathable performance

Abstract

Water/windproof and breathable membranes are important in many applications due to their resistance to water and wind penetration as well as permissibility of vapor transmitting; nevertheless, fabrication of such membranes remains a serious challenge. Herein, we have prepared a novel kind of hydrophobic fibrous membrane with good water/windproof and breathable performance via electrospinning by using polyvinylidene fluoride (PVDF) as a raw polymer. The fibrous and porous structure of the membranes have been finely regulated by tuning the DMAc/acetone ratios and NaCl concentrations in the PVDF solutions. The resultant fibrous membranes obtained from the solutions with a DMAc/acetone ratio of 7/3 and NaCl concentration of 0.003 wt% possessed an optimized porous structure with maximum pore size of 1.2 μm, mean pore size of 0.8 μm and porosity of 76.2%. The synergetic effect of hydrophobicity and porous structure endowed the membranes with simultaneously good waterproof (hydrostatic pressure of 110 kPa), windproof (air permeability of 6.1 mm s⁻¹) and breathable (water vapor transmission rate of 11.5 kg m⁻² d⁻¹) performance. Meanwhile, the PVDF resultant membranes also exhibited robust mechanical performance with high strength (breakage stress of 11.1 MPa) and excellent toughness (energy to break of 6.4 mJ m⁻³). Therefore, the as-prepared fibrous membranes with good water/windproof and breathable performance, as well as robust mechanical property, would become a key material in many areas, especially in fabricating protective clothing.