Two-component polymer brushes (polystyrene and poly(2-vinylpyridine)) were synthesized by grafting from the surface of Si-wafers. The brushes are sensitive to the surrounding medium, and their morphology and composition of the top of a brush can be switched upon exposure to different solvents. Thus surface energetic states and roughness of the film can be precisely tuned. Schematic model describing the switching of a binary polymer brush. Initially, the brush is exposed to the selective solvent of polymer A (a). The chains of polymer A (light gray) approach a swollen conformation, while the chains of polymer B (dark gray) approach a collapsed conformation. The the layer is exposed to a common nonselective solvent (b). Chains of each polymer are swollen. Upon exposure of the layer to a solvent selective for polymer B, we obtain the morphology which is inverse to the first case (c). For all the cases, the lateral phase segregation results in microphase-separated domains rich in either A or B polymers with the average width being in th order of the chain size in theta solvents.