The epoxide ring in glycidyl butyrate (model compound) and in well-defined copolymers of glycidyl methacrylate (< 40 mol %) and methyl methacrylate prepared by ATRP was efficiently opened with sodium azide in the presence of ammonium chloride in DMF at 50 degrees C. This click-type reaction led to the formation of the corresponding 1-hydroxy-2-azido compounds in high yields. The prepared azide-containing copolymers were functionalized in a second click reaction, the room temperature CuBr/N,N,N',N' ',N' '-pentamethyldiethylenetriamine-catalyzed 1,3-dipolar cycloaddition, of poly(ethylene oxide) methyl ether pentynoate to yield loosely grafted polymeric brushes with hydrophilic PEO side chains.