(Meth)acrylate polymer obtainable by polymerizing a mixture comprising a) 0.1 to 99.9% by weight of at least one (meth)acrylate of the general formula in which R 1 is hydrogen or methyl; R 2 is oxygen or NH; R 3 is a radical of the general formula II in which R 7, R 8 and R 9 independently of one another are hydrogen or methyl, n is an integer from zero to two hundred, o and p independently of one another are an integer from zero to two, and, if the sum of n and o and p is zero, R 3 is a bond; R 4 is a bond, oxygen, NH, O-CO-O, HN-CO-O, HN-CO-NH or sulphur; R 5 is hydrogen, halogen or a radical which has one to 20 carbon atoms and is optionally substituted by oxygen, nitrogen and/or sulphur, m being an integer from one to five; and R 6 is an aryl or heterocyclyl radical; and b) 99.9% to 0.1% by weight of one or a plurality of ethylenically unsaturated monomers which are different from a) and are copolymerizable with a), the components a) and b) together making 100% by weight of the polymerizable constituents of the mixture, characterized in that the (meth)acrylate polymer has a weight-average molecular weight MW in the range from greater than or equal to 1000 g/mol to less than or equal to 50 000 g/mol, MW being measured by means of gel permeation chromatography against polymethyl methacrylate standards and the polymerization being carried out in the presence of a mercaptan as chain-transfer agent. a) 0.1 to 99.9% by weight of at least one (meth)acrylate of the general formula in which R 1 is hydrogen or methyl; R 2 is oxygen or NH; R 3 is a radical of the general formula II in which R 7, R 8 and R 9 independently of one another are hydrogen or methyl, n is an integer from zero to two hundred, o and p independently of one another are an integer from zero to two, and, if the sum of n and o and p is zero, R 3 is a bond; R 4 is a bond, oxygen, NH, O-CO-O, HN-CO-O, HN-CO-NH or sulphur; R 5 is hydrogen, halogen or a radical which has one to 20 carbon atoms and is optionally substituted by oxygen, nitrogen and/or sulphur, m being an integer from one to five; and R 6 is an aryl or heterocyclyl radical; and in which R 1 is hydrogen or methyl; R 2 is oxygen or NH; R 3 is a radical of the general formula II R 7, R 8 and R 9 independently of one another are hydrogen or methyl, n is an integer from zero to two hundred, o and p independently of one another are an integer from zero to two, and, if the sum of n and o and p is zero, R 3 is a bond; R 4 is a bond, oxygen, NH, O-CO-O, HN-CO-O, HN-CO-NH or sulphur; R 5 is hydrogen, halogen or a radical which has one to 20 carbon atoms and is optionally substituted by oxygen, nitrogen and/or sulphur, m being an integer from one to five; and R 6 is an aryl or heterocyclyl radical; b) 99.9% to 0.1% by weight of one or a plurality of ethylenically unsaturated monomers which are different from a) and are copolymerizable with a), the components a) and b) together making 100% by weight of the polymerizable constituents of the mixture, characterized in that the (meth)acrylate polymer has a weight-average molecular weight MW in the range from greater than or equal to 1000 g/mol to less than or equal to 50 000 g/mol, MW being measured by means of gel permeation chromatography against polymethyl methacrylate standards and the polymerization being carried out in the presence of a mercaptan as chain-transfer agent.