Three-dimensional structured sponge with high oil wettability for the clean-up of oil contaminations and separation of oil–water mixtures

Oil spills not only result in extensive economic losses but also damage marine ecological environments. A series of materials with special wettability are investigated for the separation of oil–water mixtures. However, few studies have investigated the adsorption behaviors of sponges to crude oil (high viscosity). To solve the restrictions of high viscosity oil absorption, low oil absorption rate and oil–water emulsion separation of oil absorption materials, a superhydrophobic and superoleophilic polyurethane (PU) sponge was synthesized via an environmentally friendly surface grafting of a polymer molecular brush. This grafted sponge exhibited high oil absorption rate because of the expansion in oil and collapse in water of the polymer molecular brushes. The grafted PU sponge also possessed high absorption capacity (23 times of the self weight), high oil retention (93%), high mechanical strength and good recyclability (more than 400 times). We anticipate that the grafted sponge will have numerous applications and will show outstanding performance on a larger scale. A quick clean-up of marine spilled oil/organic solvents and the separation/recycling of an oil–water mixture/emulsion can also be achieved.