Water Vapor-Assisted Electrospinning Construction of a Double-Reentrant-Analogous Surface Topography for a Durable, Fluorine-Free Superomniphobic PS/OTS Fibrous Membrane

Fluorine-containing chemicals have been extensively utilized for fabrication of liquid-repellent, in particular oil-repellent, surfaces. However, such chemicals pose significant risk to both environment and human health. The development of fibrous materials with fluorine-free super-oil-repellent surfaces remains a considerable challenge. Herein, we propose an innovative water vapor-assisted electrospinning strategy for an in-situ construction of fluorine-free superomniphobic ultrathin fibers. This approach synergistically integrates electrostatic force-driven stretching, vapor-induced phase separation (VIPS) of polystyrene (PS)/octadecyltrichlorosilane (OTS)/tetrahydrofuran (THF) solution jets, and hydrolytic condensation of OTS, yielding a vesicular porous fiber surface topography characterized by a double-reentrant-analogous structure and a substantially reduced surface energy. The synergistic combination of fibrous architecture and low surface energy endows the PS/OTS membranes with superomniphobicity, exhibiting super-liquid-repellent behavior toward water and a series of polar and nonpolar liquids having surface tension ranging from 28.4 to 72.8 mN/m. Benefiting from the hierarchical roughness-induced nonwetting properties, the membrane shows fluffy morphology and thermal insulation performance with a thermal conductivity of 0.018 W/m·K at a loading weight of ∼12 g/m2. Moreover, the PS/OTS membrane demonstrates excellent chemical and physical durability, maintaining structural integrity and liquid repellent property under severe conditions, such as chemical corrosion, UV irradiation, and ultrasonication.