Separation of oily waste water and emulsified water/oil mixtures has gained much social attention due to the
increasing emission of industrial waste water and sanitary sewage. However, endowing a material with the
capacity of separating multiple immiscible water/oil mixtures and emulsified water-in-oil/oil-in-water mixtures
is still challengeable but urgently desirable. Herein, a universal layer-by-layer assembly method utilizing the
electrostatic attraction between polyethyleneimine (PEI) and SiO2 nanoparticles has been adopted in fabricating
superwetting materials regardless of the substrates. The as-prepared materials which possess both superhydrophilicity/
underwater superoleophobicity and superoleophilicity/underoil superhydrophobicity present
high separation capability without any pre-wetting treatment towards various water/oil mixtures, including
water/heavy oil mixtures, water/light oil mixtures, water-in-oil emulsions and oil-in-water emulsions.
Significantly, the addition of (3-Glycidyloxypropyl) trimethoxysilane (KH-560) acting as a crosslinking agent
with PEI endues as-prepared materials excellent durability and chemical stability in cyclic separations and extreme
environments, respectively. Benefitting from the universality and substrate-independency of LbL-assembly,
the method adopted in this paper could satisfy multiple demands of industry by applying on desirable
substrates.