Underwater superoleophobicity

As mentioned above, the superhydrophobic-material-based oil/water separation device faces the practical issue that water is usually heavier than oil, which limits the productivity during the separation process. It is thus rational to develop a separation device on the basis of superhydrophilic materials. Among all the superhydrophilic materials, hydrogels exhibit the most robust underwater superoleophobicity and therefore, they are the most ideal candidates for such separation systems. 

Figure 10.15 Underwater superoleophobicity of the microhaired wood-based surface treated with argon plasma (0.2 mbar, 30 W, 120 s). (a) Schematic of the underwater contact angle measurement. Water trapped between microhairs limits the contact between oil and solid, (b) Photograph of a 7 pi oil droplet deposited under water on the plasma-treated microhaired surface with the oil contact angle of 157° [21].

M. N. Kavalenka, A. Hopf, M. Schneider, M. Worgull and H. Holscher, Wood-based microhaired superhydrophobic and underwater superoleophobic surfaces for oil/water separation RSCAdv., 4,31079-31083 (2014). 

---