Superhydrophilic, Underwater Directional Oil-transport Fabrics with a Novel Oil Trapping Function.

In this study, we have prepared a novel superhydrophilic fabric that has underwater directional oil transport capability. The fabric was prepared using a two-step process consisting of dip-coating of a crosslinkable polymer, which comprises both oleophilic and hydrophilic groups, onto fabric substrate and single side UV irradiation of the coated fabric. The fabric had in air superhydrophilicity on the two side, and it can be wetted easily once immersed in water. The treated fabric showed underwater oleophobicity on the UV-exposed surface, whereas the unexposed back side still maintained underwater oleophilicity. At the optimized condition, the fabric in water transports oil automatically from the UV-exposed to the unexposed back side, but stops oil transport in the opposite direction. Such a directional oil transport takes place without the need for oil pre-wetting or formation of plastron layer on fabric. UV irradiation time showed an effect on oil transport ability. We further showed that the underwater directional oil transport fabric had a novel "oil trapping" ability. When used to seal a container, the fabric can trap oil into the container, and once trapped the oil was kept without releasing. This underwater directional oil transport fabric may be useful for development of high efficiency oil recovery systems.