Functionalized MoS₂/polyurethane sponge: An efficient scavenger for oil in water

Advanced materials with special wettability hold promise in environmental remediation, catalysis or superfluid, and have attracted a great deal of interest in the last years. Herein, a composite material consisting of a molybdenum sulfide/polyurethane sponge (MoS₂/PU) was fabricated through MoS₂ nanosheets loading onto PU using high-intensity sonication and subsequent chemical functionalization by in-situ generated diazonium salts. The MoS₂ enhanced the hydrophobicity and roughness of the PU sponge and its surface could be effectively modified with aryl and carbon-fluorine groups through diazonium chemistry. The resulting F-MoS₂/PU interface exhibited exceptional superhydrophobic/superoleophilic wettability, and allowed to separate oil/water mixtures and eliminate selectively oil from underwater or emulsions. Besides, due to the cavitation effect of high-intensity ultrasound, the exfoliated MoS₂ sheets were strongly anchored onto the PU sponge. Loading MoS₂ and/or diazonium molecules did not induce any adverse effect on the adsorption capacity of the sponge with values ranging from 25 to 90 gg⁻¹ for different organic solvents (hexane, diethyl ether, ethanol, toluene, rapeseed oil, acetonitrile, dichloromethane and chloroform). Additionally, the hydrophobic groups covalently bonded to the surface conferred excellent stability to the MoS₂/PU material during repeated cycles of oil/water separation, or upon exposure to harsh environments (−20 or +120 °C, acid solution of pH = 1 and base solution of pH = 14, NaCl solution of 3.0%, natural seawater, ethanol and chloroform).