Polymer comprising the following repeating unit I: wherein: • R 1 are each independently a hydrogen atom, a C 1 to C 4 alkyl or hydroxyalkyl group, or a C 2 to C 4 alkenyl group; • R 2 are each independently a C 2 to C 10 alkylene group; • R 3 are each independently a hydrogen atom, a C 1 to C 4 alkyl or hydroxyalkyl group, or a C 2 to C 4 alkenyl group; • R 4 represents an oxyalkylene group of formula A: (-CHR 6 CH 2) a -(OCH 2 CHR 7) b -(OCH 2 CHR 8) c -(OCH 2 CHR 9) d wherein "a" represents 1; "b" represents an integer of 1 or more; "c" and "d" represent independently from one another an integer of 0 or more; and R 6, R 7, R 8 and R 9 represent independently from one another a hydrogen atom or a C 1 to C 4 alkyl group; • R 5 represents an alkylene group, an oxyalkylene group of formula A, a cycloalkylene group, or an arylene group, optionally substituted and/or interrupted by one or more heteroatoms or heteroatom containing groups; • Y represents an oxygen atom, -NR 10 - or -N + R 11 R 12 - wherein • R 10 represents a hydrogen atom or a radical deriving from any electrophilic compound present in the reaction mixture during the synthesis process of the polymer and that reacted by alkylation reaction with a secondary amine (Y = -NH-) present on the polymer during its synthesis; and • R 11 and R 12 represent radicals deriving from any electrophilic compounds present in the reaction mixture during the synthesis process of the polymer and that reacted by successive alkylation reactions with a secondary amine (Y = -NH-) and then a tertiary amine (e.g. Y = -NR 11 -) present on the polymer during its synthesis; • k represents a positive integer from 1 to 20; • l represents a positive integer being 0 or 1; • Z represents a positive integer from 2 to 4; • n represents a positive integer from 1 to 50 • m represents a positive integer from 1 to 3 and • X represents an electrophilic group, preferably selected from halogens or sulfates. • R 1 are each independently a hydrogen atom, a C 1 to C 4 alkyl or hydroxyalkyl group, or a C 2 to C 4 alkenyl group; • R 2 are each independently a C 2 to C 10 alkylene group; • R 3 are each independently a hydrogen atom, a C 1 to C 4 alkyl or hydroxyalkyl group, or a C 2 to C 4 alkenyl group; • R 4 represents an oxyalkylene group of formula A: (-CHR 6 CH 2) a -(OCH 2 CHR 7) b -(OCH 2 CHR 8) c -(OCH 2 CHR 9) d wherein "a" represents 1; "b" represents an integer of 1 or more; "c" and "d" represent independently from one another an integer of 0 or more; and R 6, R 7, R 8 and R 9 represent independently from one another a hydrogen atom or a C 1 to C 4 alkyl group; "a" represents 1; "b" represents an integer of 1 or more; "c" and "d" represent independently from one another an integer of 0 or more; and R 6, R 7, R 8 and R 9 represent independently from one another a hydrogen atom or a C 1 to C 4 alkyl group; • R 5 represents an alkylene group, an oxyalkylene group of formula A, a cycloalkylene group, or an arylene group, optionally substituted and/or interrupted by one or more heteroatoms or heteroatom containing groups; • Y represents an oxygen atom, -NR 10 - or -N + R 11 R 12 - wherein • R 10 represents a hydrogen atom or a radical deriving from any electrophilic compound present in the reaction mixture during the synthesis process of the polymer and that reacted by alkylation reaction with a secondary amine (Y = -NH-) present on the polymer during its synthesis; and • R 11 and R 12 represent radicals deriving from any electrophilic compounds present in the reaction mixture during the synthesis process of the polymer and that reacted by successive alkylation reactions with a secondary amine (Y = -NH-) and then a tertiary amine (e.g. Y = -NR 11 -) present on the polymer during its synthesis; • R 10 represents a hydrogen atom or a radical deriving from any electrophilic compound present in the reaction mixture during the synthesis process of the polymer and that reacted by alkylation reaction with a secondary amine (Y = -NH-) present on the polymer during its synthesis; and • R 11 and R 12 represent radicals deriving from any electrophilic compounds present in the reaction mixture during the synthesis process of the polymer and that reacted by successive alkylation reactions with a secondary amine (Y = -NH-) and then a tertiary amine (e.g. Y = -NR 11 -) present on the polymer during its synthesis; • k represents a positive integer from 1 to 20; • l represents a positive integer being 0 or 1; • Z represents a positive integer from 2 to 4; • n represents a positive integer from 1 to 50 • m represents a positive integer from 1 to 3 and • X represents an electrophilic group, preferably selected from halogens or sulfates.