The synthesis of densely grafted monolayers of polymers carrying a wide spectrum of functional groups is described. To this surface-attached chains with active ester groups were generated through surface initiated polymerization of N-methacryloyl-beta-alanine N'-oxysuccinimide ester (MAC(2)AE) using a self-assembled monolayer of an azo initiator on the surfaces of silicon oxide substrates. The layer thickness of the polymer monolayers can be easily controlled through the adjustment of the monomer concentration during polymerization. The aminolysis of the active ester groups within the brush with various n-alkylamines (C-3-C-18) was studied by infrared and surface plasmon spectroscopy. It is also shown that amines that carry additional functional groups such as amino acids, sugars, dyes, crown ethers, and aminoterminated polymers such as poly(ethylene glycol) derivatives can be used to incorporate many different functional moieties into the polymers.