Fluorinated polyurethane macroporous membranes with waterproof, breathable and mechanical performance improved by lithium chloride

Abstract

Macroporous membranes that could completely resist liquid water penetration and easily permit water vapor transmission would have great significance in numerous areas. However, current fabrication strategies for such materials still suffer from a series of problems. Herein, we reported a kind of waterproof and breathable macroporous membrane fabricated from polyurethane (PU), fluorinated polyurethane (FPU), and lithium chloride (LiCl) via electrospinning. Benefiting from the diversification of conductivity adjusted by LiCl, characteristics of the membranes including fiber diameter, pore size and distribution, even the orientation and aggregation of macromolecules could be simultaneously regulated, which brought about tremendous improvement of waterproof, breathable and mechanical performance. Significantly, the relationship among waterproofness, wettability and pore size has been confirmed to be finely consistent with the Young–Laplace equation. Meanwhile, mechanical performance was investigated on the basis of macromolecular orientation that was evaluated by polarized infrared spectroscopy. Ultimately, the resultant membranes exhibited integrated performance with improved hydrostatic pressure (82.1 kPa) and water vapor transmission rate (10.9 kg m⁻² d⁻¹), as well as enhanced tensile strength (11.6 MPa) and bursting strength (8.2 kPa), which would make them promising alternatives for many potential applications, especially in protective clothing fabrication.