Copolymer consisting of a) 16 to 95 mol% of a cationic structural unit. b) 5 to 55 mol% of a macromonomeric structural unit, and c) up to 80 mol% of a structural unit, d) up to 80 mol% of a structural unit other than the structural unit, wherein the structural unit includes at least one unit of the following general formulae and/or: where R 1 in each occurrence is the same or different and represents hydrogen and/or methyl, R 2 = R 3, R 4 and R 5 in each occurrence are the same or different and each independently represent hydrogen, an aliphatic hydrocarbonaceous moiety having 1 to 20 carbon atoms, a cycloaliphatic hydrocarbonaceous moiety having 5 to 8 carbon atoms and/or aryl having 6 to 14 carbon atoms or polyethylene glycol, Y in each occurrence is the same or different and represents oxygen, -NH and/or -NR 3, V in each occurrence is the same or different and represents -(CH 2) x -, where x in each occurrence is the same or different and represents an integer from 1 to 6, X in each occurrence is the same or different and represents a halogen atom, C 1 - to C 4 -alkyl sulfate and/or C 1 - to C 4 -alkyl sulfonate, and the macromonomeric structural unit is represented by the general formulae (IIIa) and/or (IIIb) in the polymer: where R 6, R 7 and R 8 in each occurrence are the same or different and each independently represent H and/or branched or unbranched C 1 - C 4 alkyl; E in each occurrence is the same or different and represents branched or unbranched C 1 - C 6 alkylene, cyclohexyl, CH 2 -C 6 H 1, ortho-, meta- or para-substituted C 6 H 4 and/or a unit not present; G in each occurrence is the same or different and represents O, NH and/or CO-NH with the proviso that when E is a unit not present, G is also a unit not present; A in each occurrence is the same or different and represents C x H 2x where x = 2, 3, 4 and/or 5 (preferably x = 2) and/or CH 2 CH(C 6 H 5); n in each occurrence is the same or different and represents 0, 1, 2, 3, 4 and/or 5; a in each occurrence is the same or different and represents an integer from 5 to 350 (preferably 10 - 200); R 9 in each occurrence is the same or different and represents H, a branched or unbranched C 1 -C 4 alkyl, CO-NH 2, and/or COCH 3; where R 3 is as defined above and in the case of PEG the latter has 5 to 350 and preferably 10 to 200 ethylene oxide units. a) 16 to 95 mol% of a cationic structural unit. b) 5 to 55 mol% of a macromonomeric structural unit, and c) up to 80 mol% of a structural unit, d) up to 80 mol% of a structural unit other than the structural unit, R 1 in each occurrence is the same or different and represents hydrogen and/or methyl, R 2 = R 3, R 4 and R 5 in each occurrence are the same or different and each independently represent hydrogen, an aliphatic hydrocarbonaceous moiety having 1 to 20 carbon atoms, a cycloaliphatic hydrocarbonaceous moiety having 5 to 8 carbon atoms and/or aryl having 6 to 14 carbon atoms or polyethylene glycol, Y in each occurrence is the same or different and represents oxygen, -NH and/or -NR 3, V in each occurrence is the same or different and represents -(CH 2) x -, where x in each occurrence is the same or different and represents an integer from 1 to 6, X in each occurrence is the same or different and represents a halogen atom, C 1 - to C 4 -alkyl sulfate and/or C 1 - to C 4 -alkyl sulfonate, R 6, R 7 and R 8 in each occurrence are the same or different and each independently represent H and/or branched or unbranched C 1 - C 4 alkyl; E in each occurrence is the same or different and represents branched or unbranched C 1 - C 6 alkylene, cyclohexyl, CH 2 -C 6 H 1, ortho-, meta- or para-substituted C 6 H 4 and/or a unit not present; G in each occurrence is the same or different and represents O, NH and/or CO-NH with the proviso that when E is a unit not present, G is also a unit not present; A in each occurrence is the same or different and represents C x H 2x where x = 2, 3, 4 and/or 5 (preferably x = 2) and/or CH 2 CH(C 6 H 5); n in each occurrence is the same or different and represents 0, 1, 2, 3, 4 and/or 5; a in each occurrence is the same or different and represents an integer from 5 to 350 (preferably 10 - 200); R 9 in each occurrence is the same or different and represents H, a branched or unbranched C 1 -C 4 alkyl, CO-NH 2, and/or COCH 3;