Polydopamine as a Versatile Adhesive Layer for Robust Fabrication of Smart Surface with Switchable Wettability for Effective Oil/Water Separation

A smart material with switchable
surface wettability is highly
desired for the practical application in removing oil from oily wastewater.
In this work, we developed a robust and simple method to functionalize
various substrate materials, such as a melamine sponge and nonwoven
textile, with switchable surface oil wettability at varied media with
different pHs. The modification method involves oxidative self-polymerization
of dopamine on the material surface and subsequently functionalizing
with a block copolymer, namely poly­(2-vinylpyridine-b-dimethylsiloxane) (P2VP-b-PDMS). The as-functionalized
materials display stable and continuous switchable wettability. The
materials switch their wettability by simply responding to aqueous
pH, and the switch is achieved at room temperature and involves no
organic solvent. The materials show excellent oil/water separation
performance for different kinds of oils and exhibit durability in
strong alkaline and corrosive solutions. This robust and simple chemical
modification strategy reduces the production cost of smart materials
with switchable wettability and thus would lead to their mass production
and applications toward solving practical industrial problems.