Polymer brushes have recently emerged as an extremely versatile way to modify surface properties in a robust and controlled way. The introduction of responsive polymers and block copolymers in polymer-brush systems has also opened up new routes to 'smart' surfaces with switchable surface properties. here, the use of polyelectrolyte brushes as a supramolecular platform for the immobilization of a wide range of species, leading to a tunable wettability of substrates, is presented.