One-step preparation of modified photothermal-driven melamine foam with gradient wettability for oil–water separation

The absorption of high-viscosity oil by traditional oil absorbing materials has always been a challenge. So there is an urgent need to solve the problem of slow absorption of high-viscosity oil. In this work, an emulsion composed of polydimethylsiloxane (PDMS), carbon black (CB) and waterborne polyurethane (solid content 40%) was sprayed on the melamine foam (MF). After volatilization of organic solvents, the photothermal material CB was fixed on the MF framework, making it photothermal. By raising the temperature of the modified foam to accelerate the internal thermal movement of high-viscosity oil molecules around the foam, intermolecular forces are reduced, thereby accelerating the separation process. The absorption capacity of this modified MF towards organic solvents and oil is up to 79 times its own weight. In addition, the mechanical properties of the modified foam are improved to a certain extent, more conducive to the continuous oil–water separation. This photothermal absorption material provides ideas for the rapid removal of high-viscosity oil, heavy oil, etc.