The research group headed by Professor ZHANG Zhaozhu at the Lanzhou Institute of Chemical Physics (LICP), Chinese Academy of Sciences (CAS), has developed new ways to fabricate superoleophobic surfaces and achieve rapid control of switchable oil wettability and adhesion on these surfaces.
Researchers have first fabricated surfaces with certain roughness on copper and aluminium substrates through acid and alkaline corrosion. These surfaces were then modified with low surface energy materials to obtain superoleophobic surfaces.
Then, through varying the surface composition, the reversible switching of oil on the surfaces have been achieved. They have developed a simple layer-by-layer (LbL) technology and counterion exchange procedure to rapidly and reversibly manipulate the oleophobicity of commercially available cotton fabrics and aluminum surfaces. Through the alternation of plasma treatment and surface fluorination, they have rapidly achieved the reversible wettability and adhesion transition to oil droplets on the copper substrate.
Moreover, the group has fabricated a novel superhydrophilic and superoleophobic nanocomposite coating by spray casting nanoparticle–polymer suspensions on various substrates. Water droplets can spread over the coating completely; meanwhile, oil droplets can roll off the coating at low tilt angles without any penetration. Besides overcoming oil-fouling problems for the hydrophilic coating, the superhydrophilic–superoleophobic coating which has been applied to the stainless steel mesh can be used for the separation of oil and water.
The work is of guiding significance for the theoretical research and application of superoleophobic surfaces. It has received support from the National Natural Science Foundation of China.
The findings have been published in J. Mater. Chem. (2012, 22, 2834-2837), Langmuir (2011, 27, 14508-14513; 2011, 27, 7357-7360), Journal of Colloid and Interface Science (2012, 366, 191-195, 2012, 367, 443-449) and New J. Chem. , (2011, 35, 2422–2426).
(a) Surface morphology of superoleophobic aluminium surface; (b) Surface morphology of superoleophobic copper surface; (c) Reversible wettability switching and adhesion switching of oil on surfaces; (d) Application of superhydrophilic and superoleophobic nanocomposite coating in oil/water separation. (Image by ZHANG Zhaozhu et al.)
J. Mater. Chem.(2012, 22, 2834-2837)
Langmuir(2011, 27, 14508-14513)
Journal of Colloid and Interface Science(2012, 366, 191-195)
Journal of Colloid and Interface Science(2012, 367, 443-449)