A polyurethane polymer which is obtainable by (i) preparation of at least one isocyanate-functional prepolymer by reacting a mixture comprising at least one polyisocyanate and at least one alkanolamine; (ii) subsequent reaction of the at least one isocyanate-functional prepolymer with at least one compound of general formula, wherein, R1, R2, R3 and R4, independent of each other, are selected from the group consisting of hydrogen, -C(=O)-OH, -C(=O)-OM 3, -OSO 3 H, -OSO 3 M 3, -OH, -OM 3, - C(=O)-H, -O-C 1-6 -alkyl, -F, -Cl, -CN, -Br, -NH 2, -NHR and -NRR', wherein at least one of R1, R2, R3 and R4 is selected from the group consisting of -NH 2 and -NHR M 1 is selected from the group consisting of hydrogen and metal cations selected from the group consisting of lithium (Li), sodium (Na), potassium, rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra), M 2 is selected from the group consisting of hydrogen and metal cations selected from the group consisting of lithium (Li), sodium (Na), potassium, rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra), M 3 are, identical or different, a metal cation selected from the group consisting of lithium (Li), sodium (Na), potassium, rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra), and R and R' are, identical or different, linear or branched, unsubstituted C 1 -C 6 alkyl. (i) preparation of at least one isocyanate-functional prepolymer by reacting a mixture comprising at least one polyisocyanate and at least one alkanolamine; (ii) subsequent reaction of the at least one isocyanate-functional prepolymer with at least one compound of general formula, wherein, R1, R2, R3 and R4, independent of each other, are selected from the group consisting of hydrogen, -C(=O)-OH, -C(=O)-OM 3, -OSO 3 H, -OSO 3 M 3, -OH, -OM 3, - C(=O)-H, -O-C 1-6 -alkyl, -F, -Cl, -CN, -Br, -NH 2, -NHR and -NRR', wherein at least one of R1, R2, R3 and R4 is selected from the group consisting of -NH 2 and -NHR M 1 is selected from the group consisting of hydrogen and metal cations selected from the group consisting of lithium (Li), sodium (Na), potassium, rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra), M 2 is selected from the group consisting of hydrogen and metal cations selected from the group consisting of lithium (Li), sodium (Na), potassium, rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra), M 3 are, identical or different, a metal cation selected from the group consisting of lithium (Li), sodium (Na), potassium, rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra), and R and R' are, identical or different, linear or branched, unsubstituted C 1 -C 6 alkyl. R1, R2, R3 and R4, independent of each other, are selected from the group consisting of hydrogen, -C(=O)-OH, -C(=O)-OM 3, -OSO 3 H, -OSO 3 M 3, -OH, -OM 3, - C(=O)-H, -O-C 1-6 -alkyl, -F, -Cl, -CN, -Br, -NH 2, -NHR and -NRR', wherein at least one of R1, R2, R3 and R4 is selected from the group consisting of -NH 2 and -NHR M 1 is selected from the group consisting of hydrogen and metal cations selected from the group consisting of lithium (Li), sodium (Na), potassium, rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra), M 2 is selected from the group consisting of hydrogen and metal cations selected from the group consisting of lithium (Li), sodium (Na), potassium, rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra), M 3 are, identical or different, a metal cation selected from the group consisting of lithium (Li), sodium (Na), potassium, rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra), and R and R' are, identical or different, linear or branched, unsubstituted C 1 -C 6 alkyl.