Facile fabrication of environmentally friendly and mechanically robust transparent, waterproof, and breathable fibrous membranes

Abstract

Functional fibrous membranes that combine optical transparency, waterproofness, and breathability are in high demand for a wide range of applications. However, these materials remain poorly developed owing to the substantial technical difficulty associated with their fabrication. Moreover, existing fabrication processes raise environmental and health concerns owing to the prevalent use of hazardous solvents. This work addresses these issues by proposing a safe, facile, and efficient strategy to fabricate transparent, waterproof, and breathable membranes (TWBMs) via an environmentally friendly process that combines electrospinning using ethanol as a green solvent and thermal curing technology involving a fluorine-free paraffin wax emulsion coating. The electrospinning process involves ethanol-soluble polyamide/aqueous polymer isocyanate fibers, and the wax coating imparts outstanding waterproofness to the fibrous membrane, while enhancing mechanical strength. Then, an optimized thermal curing process is applied to achieve a precisely controlled porous structure and membrane thickness, which generates high transparency, while preserving the microporous structure that is vital for ensuring breathability. The resulting membranes exhibit high optical transmittance of 90 %, excellent water resistance of 111.4 kPa, and adequate water vapor permeability of 5.3 kg m⁻² d⁻¹, which represent integrated properties that are far superior to those of commercially available transparent materials.