pH-sensitive wettability of polystyrene-

b

-poly(4-vinylpyridine) (PS-

b

-P4VP) self assembled films

exhibiting superoleophobicity under water and hydrophilicity at low pH value

and oleophobicity under water and hydrophobicity at neutral condition

has been realized. The wettability properties resulted from the surface topological and chemical transition

which were confirmed by

in situ

AFM measurements under water at different pH. At low pH

P4VP chains

which were confined in the hexagonal-packed nanodomains

got protonated into a swollen state

while at high pH

P4VP chains were deprotonated into a collapsed state. The reversible protonation/deprotonation procedure on the molecular scale leads to surface topological and chemical transition

thereby pH-sensitive wettability.