Underwater superoleophobic polyurethane-coated mesh with excellent stability for oil/water separation.

Oil/water separation has been a challenge in chemical engineering for various applications. There are numbers of studies on using coated metal meshes as a filter for oil/water separation. However, water resistance, chemical (such as: acid, base, and fouling) resistance and heat resistance for coating materials need further exploration, especially in terms of the durability of the coating materials. In this study, we synthesized a new coating material, hydrophilic polycarbonate polyurethane (HPCPU). We used HPCPU to chemically modify a steel mesh, and the mesh exhibits superhydrophilic and underwater superoleophobic properties. The HPCPU coated mesh shows excellent capacity for oil/water separation with a separation efficiency higher than 99.99% even after 40 cycles of separation. The coating material also exhibits excellent properties of water resistance, heat resistance, and chemical resistance. Moreover, the HPCPU-coated mesh exhibits a strong durability. For example, the separation efficiency for various oil/water mixtures remains higher than 99.7% after the HPCPU-coated mesh has been soaked in water for 30 days, hot water for 5 days, oils for 5 days, 0.5 M HCl solution, 0.5 M NaOH solution and 0.5 M NaCl solution for 24 hours.