  We use density functional theory to investigate adsorption of liquid mixtures
on solid surfaces modified with end-grafted chains. The chains are modelled as
freely joined spheres. The fluid molecules are spherical. All spherical species
interact via the Lennard-Jones (12-6) potential. The Lennard-Jones (9-3)
potential describes interactions of solvent molecules with the substrate. We
study the relative excess adsorption isotherms, the structure of surface layer
and its composition. The impact of the following parameters on adsorption is
discussed: the grafting density, the grafted chain length, interactions of
solvent molecules with grafted chains and with the substrate, and the presence
of active groups in grafted chains. The theoretical results are consistent with
experimental observations.
