Robust Fluorine-Free Superhydrophobic Amino-Silicone Oil/SiO2 Modification of Electrospun Polyacrylonitrile Membranes for Waterproof-Breathable Application.

Superhydrophobic waterproof-breathable membranes have attracted considerable interest owing to their multifunctional applications in self-cleaning, anti-icing, anticorrosion, outdoor tents, and protective clothing. Despite the researches pertaning to the construction of superhydrophobic functional membranes by nanoparticle finishing have increased drastically, the disconnected particle component is easy to fall off from the membranes under deformation and wear conditions, which has restricted their wide use in practice. Here, robust superhydrophobic microporous membranes were prepared via a facile and environmentally friendly strategy by dip-coating amino-silicone oil (ASO) onto the electrospun polyacrylonitrile (PAN) membranes, followed by SiO2 nanoparticles (SiO2 NPs) blade coating. Compared with hydrophilic PAN membranes, the modified membranes exhibited superhydrophobic surface with an advancing water contact angle up to 156°, after introducing ASO as low surface energy substance and SiO2 NPs as filler to reduce the pore size and construct the multihierarchical rough structure. Varying the concentrations of ASO and SiO2 NPs systematically, the PAN electrospun membranes modified with 1 wt % ASO and 0.1 wt % SiO2 NPs were endowed with good water-resistance (74.3 kPa), relative low thermal conductivity (0.0028 W m-1 K-1), modest vapor permeability (11.4 kg m-2 d-1), and air permeability (20.5 mm s-1). Besides, the inorganic-organic hybrid coating of ASO/SiO2 NPs could maintain its superhydrophobicity even after 40 abrasion cycles. The resulting membranes were found to resist variations on the pH scale from 0 to 12, and retained their water repellent properties when exposed to harsh acidic and alkali conditions. This facile fabrication of durable fluorine-free superhydrophobic membranes simultaneous with good waterproof-breathable performance provides the advantages for potential applications in self-cleaning materials and versatile protective clothing.