Nonfouling Capture-Release Substrates Based on Polymer Brushes for Separation of Water-Dispersed Oil Droplets

摘要

We have demonstrated capture and release of underwater—oil droplets based on fouling-resistant surfaces coated with pH-responsive polymer brushes. In response to the change of environmental pH, oil droplets were captured on the polymer brush-modified surfaces in the high adhesion state. As the droplet volume increased upon coalescence with other oil droplets in the aqueous phase, the captured droplets eventually self-released from the surfaces under the influence of buoyancy and rose to the air—water interface. The fact that the polymer brush surfaces were partially oil-wettable (high oil-in-water contact angles) enabled the adhesion but not the spreading of oil droplets. This allowed buoyancy release of oil droplets and led to fouling-resistant surfaces that could be reused for capture—release of more oil droplets. The practicality and versatility of this oil droplet capture—release system was demonstrated using monodisperse and polydisperse hydrocarbon oil compositions in purified water, tap water, and brines in which the salt concentration was as high as that of seawater.