UV-Cured Fluoride-Free Polyurethane Functionalized Textile with pH-Induced Switchable Superhydrophobicity and Underwater Superoleophobicity for Controllable Oil/Water Separation

Design
and fabrication of smart surfaces for separation of oily
water have been developed rapidly. Nevertheless, construction of these
smart surface materials by using green and sustainable paths for intelligent
separation of oily water still faces huge challenges. The aim of this
study was to develop a facile, sustainable, and energy-efficient approach
for the fabrication of smart coatings with pH-responsive switchable
wettability. The coating was formed on the textiles from UV-cured
fluoride-free pH-responsive polyurethane (pH-PU). The wettability
of obtained textiles could switch reversibly between superhydrophobicity
and underwater superoleophobicity due to the protonation and deprotonation
of the pH-PU under different pH conditions, which was used to successfully
separate either oil or water from oily water with high separation
efficiencies. More importantly, oil-in-water and water-in-oil emulsions
could all be selectively separated with high water flux and oil purity
by as-fabricated textiles, and these pH-PU-functionalized textiles
or sponges effectively performed for oil collection of oil spilled
on water. Our work provided a fast, economical, and sustainable pathway
to prepare smart coatings with switchable wettability for both environmental
protection and energy-saving merits.