Preparation of underwater superoleophobic porous coating via a co-deposition method for oil/water mixture separation

Oil contamination is problematic in subaqueous environments. Here, a cationic poly(N,N-dimethyl-N-(ethoxycarbonylmethyl)-N-[2 '-(methacryloyloxy)ethyl]- ammonium chloride) (PCBMAE) was synthesized, and a one-step approach of dopamine-assisted codeposition was used to generate PCBMAE/polydopamine (PDA) superhydrophilic and underwater superoleophobic coatings coated on a stainless steel mesh for oil/water separation. The structures, surface morphologies, and properties of the coatings were analyzed by IR, SEM, TGA, and contact angle measurements. During deposition at a PCBMAE and DA mass ratio of 1:1, PCBMAE/PDA mixture particles uniformly adhered to the skeletons of the mesh, increased the surface roughness, created enriched surface micro/nanostructures, and reduced the surface energy of the coating. This endowed the metal mesh with superhydrophilicity and underwater superoleophobicity (oil contact angle 163 degrees) without blocking the mesh, and the deposition density was 0.26 mg/cm(2). The separation efficiency of the coated mesh was 99.6% for the first castor oil/water separation and dropped to 98.0% after 5 cycles. After 25 cycles, the separation efficiency was still higher than 95%. The PCBMAE/PDA codeposited mesh exhibited high oil/water separation efficiency, stable mechanical properties, and weather stability under different harsh environments, making it a promising separation material for future industrial applications.

Automated summary

A new coating with superhydrophilicity and underwater superoleophobicity was synthesized for oil/water separation in subaqueous environments. The coating demonstrated high oil/water separation efficiency, stability, and weather resistance even after multiple cycles.