Environmental Remedy of Oil Contamination by Superhydrophobic Thiol-Modified Nanomotors

The issue of pollution through oil spills in aquatic habitats is among the most difficult to address due to ocean currents and lack of effective containment procedures. A potential resolution to water pollution is investigated with synthetic self-propelled superhyrdophobic nanomotors capable of targeting, transporting, and isolating olive and motor oil droplets in contaminated samples. The conical microengines, range from 8-10 µm in size, are propelled based on platinum-hydrogen peroxide catalytic reactions that occur within the inner platinum surface. Such engines are prepared by a low cost membrane-template electrodeposition method that provides their Au/Ni/PEDOT/Pt multilayer composition, respectively. Exterior Au surface of the Au/Ni/PEDOT/Pt microengines are further functionalized with alkanethiol self-assembled-monolayer (SAM) chains (C6, C12, C18), which provides their superhydrophobic properties. We examine the efficiency of the interaction between free floating oil droplets in water and hydrophobic alkanethiol chains-modified microengines as well as the resultant speed. Large towing force, fast speed and high efficiency of our microengines were observed, being able to carry up to 65 (1.7 µm size) oil droplets attached to the SAM-coated microengine exterior surface. While no such oil-motor interactions were observed in control experiments involving both unmodified microengines and microengines coated with SAM layers containing a polar-terminal group. These results demonstrate that such SAM-Au/Ni/PEDOT/Pt micromachines can be useful for a facile, rapid and efficient collection of oils in water samples. The integration of oil-sorption properties into self-propelled microengines holds great promise for the remediation of oil-contaminated water samples or the isolation of other hydrophobic targets, such as drugs.