In Situ and Ex Situ pH-Responsive Coatings with Switchable Wettability for Controllable Oil/Water Separation

The
development of stimuli-responsive materials with the ability
of controllable oil/water separation is crucial for practical applications.
Here, a novel pH responsive nonfluorine-containing copolymer was designed.
The copolymer together with silica can be dip-coated on different
materials including cotton fabric, filter paper, and polyurethane
foam. The coated materials exhibit switchable superhydrophilicity
and superhydrophobicity and can be applied in continuous separation
of oil/water/oil three phase mixtures, different surfactant stabilized
emulsion (oil-in-water, water-in-oil, and oil-in-acidic water) as
well as oil uptake and release via in situ and ex situ pH change.
We expect that the coatings highlight the practical applications because
of the cost-effective preparation process and fluorine-free strategy.