Underwater superoleophilic to superoleophobic wetting control on the nanostructured copper substrates

Surfaces with controlled underwater oil wettability would offer great promise in the design and fabrication of novel materials for advanced applications. Herein, we propose a new approach based on self-assembly of mixed thiols (containing both HS(CH₂)₉CH₃ and HS(CH₂)₁₁OH) on nanostructured copper substrates for the fabrication of surfaces with controlled underwater oil wettability. By simply changing the concentration of HS(CH₂)₁₁OH in the solution, surfaces with controlled oil wettability from the underwater superoleophilicity to superoleophobicity can be achieved. The tunable effect can be due to the synergistic effect of the surface chemistry variation and the nanostructures on the surfaces. Noticeably, the amplified effect of the nanostructures can provide better control of the underwater oil wettability between the two extremes: superoleophilicity and superoleophobicity. Moreover, we also extended the strategy to the copper mesh substrates and realized the selective oil/water separation on the as-prepared copper mesh films. This report offers a flexible approach of fabricating surfaces with controlled oil wettability, which can be further applied to other ordinary materials, and open up new perspectives in manipulation of the surface oil wettability in water.