Reduced Graphene Oxide-Doped Porous Thermoplastic Polyurethane Sponges for Highly Efficient Oil/Water Separation

In this paper, a porous polyurethane sponge with excellent hydrophobicity was prepared through thermal phase separation. Preparation condition modified experiments were systematically carried out, and a sponge with a saturated oil absorption capacity (13.3 g g^-1) and a rapid absorption rate (achieving absorption equilibrium within 20 s) was achieved. The thermoplastic polyurethane (TPU) sponge as an oil absorbent is capable of selectively absorbing various oils/organic solvents from oil/water mixtures with a high recovery rate. To further enhance the hydrophobicity and mechanical properties of the porous sponge, 3% reduced graphene oxide was doped to this material. The morphological investigation indicated that the three-dimensional composite sponges have uniformly distributed micropores and nanopores, and the hydrophobicity and mechanical properties were improved. The composite as a whole exhibited remarkable superelasticity, excellent reversible compressibility, and fatigue resistance (strength up to 186 kPa at 80% strain), which allows it to re-absorb oil by simple manual extrusion. The abovementioned properties make this TPU porous material a promising candidate for practical application in water pollution treatment.