Emulsion-templated, hydrophilic and underwater oleophobic PVA aerogels with enhanced mechanical property

Emulsion-templated, hydrophilic-oleophobic porous materials are promising for various applications, but their relatively weak mechanical properties of the resulting materials hinder them from real applications. Herein, we report the fabrication of emulsion-templated, hydrophilic and underwater oleophobic poly(vinyl alcohol) aerogels with enhanced mechanical property, bereft of the use of fluorine-containing components. The resulting aerogels exhibited flexibility, compression and stretchability both in dry and in wet states, showing enhanced compressive and tensile performances. The hydrophilicity and underwater oleophobicity enabled the pre-wet aerogels to have anti-fouling property and suitable for removing water from oil-water mixtures and surfactant-stabilized, water-in-oil emulsions. Taking their advantageous wettability, the aerogels were studied for solar steam evaporation from oil-containing salt aqueous solution after coating a thin layer of carbon nanotubes at the top. The evaporators showed high water evaporation rate (up to 2.7 kg m−2 h−1), high light-to-thermal conversion efficiency (up to 99%) and excellent continuous evaporation rate at 2.1 kg m−2 h−1 after 10 h′ continuous evaporation. The hydrophilicity, underwater oleophobicity and enhanced mechanical properties enabled the PVA aerogels as good candidates for removing water from various oil-water mixtures and for preparing solar steam evaporators.