A water-soluble or water-swellable copolymer obtainable by free-radical copolymerization of A) acryloyldimethyltaurine and/or acryloyldimethyltaurates, B) if desired, one or more olefinically unsaturated, optionally crosslinking comonomers containing at least one oxygen, nitrogen, sulfur or phosphorus atom and possessing a molecular weight of less than 500 g/mol, and selected from unsaturated carboxylic acids and their anhydrides and salts, and also their esters with aliphatic, olefinic, cycloaliphatic, arylaliphatic or aromatic alcohols having a carbon number of from 1 to 22, open-chain N-vinyl amides, preferably N-vinylformamide (VIFA), N-vinylmethylformamide, N-vinylmethylacetamide (VIMA) and N-vinylacetamide; cyclic N-vinyl amides (N-vinyl lactams) with a ring size of 3 to 9, preferably N-vinylpyrrolidone and N-vinylcaprolactam; amides of acrylic and methacrylic acid, preferably acrylamide, methacrylamide, N,N-dimethylacrylamide, N,N-diethylacrylamide, and N,N-diisopropylacrylamide; alkoxylated acrylamides and methacrylamides, preferably hydroxyethyl methacrylate, hydroxymethyl-methacrylamide, hydroxyethylmethacrylamide, hydroxypropylmethacrylamide, and mono [2-(methacryloyloxy)ethyl] succinate; N,N-dimethylamino methacrylate; diethylaminomethyl methacrylate; acrylamido- and methacrylamidoglycolic acid; 2- and 4-vinylpyridine; vinyl acetate; glycidyl methacrylate; styrene; acrylonitrile; vinyl chloride; stearyl acrylate; lauryl methacrylate; vinylidene chloride; and/or tetrafluoroethylene; inorganic acids and their salts and esters, preferably vinylphosphonic acid, vinylsulfonic acid, allylphosphonic acid, and methallylsulfonic acid, C) one or more at least monofunctional, silicon-containing components capable of free-radical polymerization, at least one silicon-containing component being a compound selected from the formulae where f = 2 to 500 where f = 2 to 500 and/or where f = 2 to 500, the copolymerization D) taking place in the presence of at least one polymeric additive having number-average molecular weights of from 200 g/mol to 10 9 g/mol selected from homopolymers and copolymers of N-vinylformamide, N-vinylacetamide, N-vinylpyrrolidone, acryloyldimethyltaurine, N-vinylcaprolactam, N-vinylmethylacetamide, acrylamide, acrylic acid, methacrylic acid, N-vinylmorpholide, hydroxy ethyl methacrylate, diallyldimethylammonium choride (DADMAC) and/or [2-(methacryloyloxy)ethyl]trimethylammonium chloride (MAPTAC). A) acryloyldimethyltaurine and/or acryloyldimethyltaurates, B) if desired, one or more olefinically unsaturated, optionally crosslinking comonomers containing at least one oxygen, nitrogen, sulfur or phosphorus atom and possessing a molecular weight of less than 500 g/mol, and selected from unsaturated carboxylic acids and their anhydrides and salts, and also their esters with aliphatic, olefinic, cycloaliphatic, arylaliphatic or aromatic alcohols having a carbon number of from 1 to 22, open-chain N-vinyl amides, preferably N-vinylformamide (VIFA), N-vinylmethylformamide, N-vinylmethylacetamide (VIMA) and N-vinylacetamide; cyclic N-vinyl amides (N-vinyl lactams) with a ring size of 3 to 9, preferably N-vinylpyrrolidone and N-vinylcaprolactam; amides of acrylic and methacrylic acid, preferably acrylamide, methacrylamide, N,N-dimethylacrylamide, N,N-diethylacrylamide, and N,N-diisopropylacrylamide; alkoxylated acrylamides and methacrylamides, preferably hydroxyethyl methacrylate, hydroxymethyl-methacrylamide, hydroxyethylmethacrylamide, hydroxypropylmethacrylamide, and mono [2-(methacryloyloxy)ethyl] succinate; N,N-dimethylamino methacrylate; diethylaminomethyl methacrylate; acrylamido- and methacrylamidoglycolic acid; 2- and 4-vinylpyridine; vinyl acetate; glycidyl methacrylate; styrene; acrylonitrile; vinyl chloride; stearyl acrylate; lauryl methacrylate; vinylidene chloride; and/or tetrafluoroethylene; inorganic acids and their salts and esters, preferably vinylphosphonic acid, vinylsulfonic acid, allylphosphonic acid, and methallylsulfonic acid, C) one or more at least monofunctional, silicon-containing components capable of free-radical polymerization, at least one silicon-containing component being a compound selected from the formulae where f = 2 to 500 where f = 2 to 500 and/or where f = 2 to 500, the copolymerization D) taking place in the presence of at least one polymeric additive having number-average molecular weights of from 200 g/mol to 10 9 g/mol selected from homopolymers and copolymers of N-vinylformamide, N-vinylacetamide, N-vinylpyrrolidone, acryloyldimethyltaurine, N-vinylcaprolactam, N-vinylmethylacetamide, acrylamide, acrylic acid, methacrylic acid, N-vinylmorpholide, hydroxy ethyl methacrylate, diallyldimethylammonium choride (DADMAC) and/or [2-(methacryloyloxy)ethyl]trimethylammonium chloride (MAPTAC).