A method to reduce the electroosmotic flow in a capillary or in a channel or to reduce the attachment of biological species to a surface comprising the steps of: - coating said capillary or channel or said surface with a copolymer comprising: i) a surface interacting copolymerized monomer, selected from the group of acrylamide, methacrylamide each being independently mono- or di-substituted on the nitrogen by C1 to C12 linear or branched alkyl, halo-substituted Cl to C12 alkyl, methoxy-substituted C1 to C12 alkyl or hydroxyl-substituted C1 to C12 alkyl, or vinylpyrrolidone, ii) a copolymerized monomer bearing a chemically active group, wherein the chemically active group is selected from the group of: thiols, primary amines, secondary amines, quaternary ammoniums, phosphines, alcohols, carboxylic acids, vinylsulfonyls, aldehydes, epoxides, hydrazides, succinimidyl esters, carbodiimides, maleimides, iodoacetyls, isocyanates, isothiocyanates, aziridines, sulfonates or halides, and iii) a copolymerized silane monomer obtainable by reacting an ethylenically unsaturated silane monomer; - optionally washing the capillary or channel or the surface with water and/or solvent; - optionally drying the capillary or channel or the surface; - and exposing the capillary or channel or the surface to a chemical entity able to block residual functional groups of the copolymer, wherein the blocking is performed by an agent selected from: ethanolamine, aminomodified polyethylenglycol, peptides, peptoids or synthetic polymers. - coating said capillary or channel or said surface with a copolymer comprising: i) a surface interacting copolymerized monomer, selected from the group of acrylamide, methacrylamide each being independently mono- or di-substituted on the nitrogen by C1 to C12 linear or branched alkyl, halo-substituted Cl to C12 alkyl, methoxy-substituted C1 to C12 alkyl or hydroxyl-substituted C1 to C12 alkyl, or vinylpyrrolidone, ii) a copolymerized monomer bearing a chemically active group, wherein the chemically active group is selected from the group of: thiols, primary amines, secondary amines, quaternary ammoniums, phosphines, alcohols, carboxylic acids, vinylsulfonyls, aldehydes, epoxides, hydrazides, succinimidyl esters, carbodiimides, maleimides, iodoacetyls, isocyanates, isothiocyanates, aziridines, sulfonates or halides, and iii) a copolymerized silane monomer obtainable by reacting an ethylenically unsaturated silane monomer; i) a surface interacting copolymerized monomer, selected from the group of acrylamide, methacrylamide each being independently mono- or di-substituted on the nitrogen by C1 to C12 linear or branched alkyl, halo-substituted Cl to C12 alkyl, methoxy-substituted C1 to C12 alkyl or hydroxyl-substituted C1 to C12 alkyl, or vinylpyrrolidone, ii) a copolymerized monomer bearing a chemically active group, wherein the chemically active group is selected from the group of: thiols, primary amines, secondary amines, quaternary ammoniums, phosphines, alcohols, carboxylic acids, vinylsulfonyls, aldehydes, epoxides, hydrazides, succinimidyl esters, carbodiimides, maleimides, iodoacetyls, isocyanates, isothiocyanates, aziridines, sulfonates or halides, and iii) a copolymerized silane monomer obtainable by reacting an ethylenically unsaturated silane monomer; - optionally washing the capillary or channel or the surface with water and/or solvent; - optionally drying the capillary or channel or the surface; - and exposing the capillary or channel or the surface to a chemical entity able to block residual functional groups of the copolymer, wherein the blocking is performed by an agent selected from: ethanolamine, aminomodified polyethylenglycol, peptides, peptoids or synthetic polymers.