A poly(aryl ether sulfone) (PAES) polymer (P1) comprising: - recurring units (R PAES ) of formula (L) : - at least one terminal group of formula (M) : wherein : - each R 1 is independently selected from the group consisting of a halogen, alkyl, alkenyl, alkynyl, aryl, ether, thioether, carboxylic acid, ester, amide, imide, alkali or alkaline earth metal sulfonate, alkyl sulfonate, alkali or alkaline earth metal phosphonate, alkyl phosphonate, amine and quaternary ammonium; - each i is an independently selected integer from 0 to 4; - T is selected from the group consisting of a bond, -CH 2 -; -O-; -SO 2 -; -S-; -C(O)-; -C(CH 3 ) 2 - ;-C(CF 3 ) 2 -; -C(=CCl 2 )-; -C(CH 3 )(CH 2 CH 2 COOH)-; -N=N-; -R a C=CR b -, where each R a and R b , independently of one another, is a hydrogen or a C1-C12-alkyl, C1-C12-alkoxy, or C6-C18-aryl group; -(CH 2 ) m - and -(CF 2 ) m - with m being an integer from 1 to 6; an aliphatic divalent group, linear or branched, of up to 6 carbon atoms; and combinations thereof; - y1 and y2 independently vary between 0 and 50, at least one of y1 or y2 being different from 0; - R' is a bond, a heteroatom, a (CH 2 -CH 2 -O) n group with n varying from 1 to 16, a C5-C40 aryl group, a C3-C40 branched aliphatic group or a C3-C40 cycloaliphatic group; and - X is Cl, Br or I. - recurring units (R PAES ) of formula (L) : - at least one terminal group of formula (M) : wherein : - each R 1 is independently selected from the group consisting of a halogen, alkyl, alkenyl, alkynyl, aryl, ether, thioether, carboxylic acid, ester, amide, imide, alkali or alkaline earth metal sulfonate, alkyl sulfonate, alkali or alkaline earth metal phosphonate, alkyl phosphonate, amine and quaternary ammonium; - each i is an independently selected integer from 0 to 4; - T is selected from the group consisting of a bond, -CH 2 -; -O-; -SO 2 -; -S-; -C(O)-; -C(CH 3 ) 2 - ;-C(CF 3 ) 2 -; -C(=CCl 2 )-; -C(CH 3 )(CH 2 CH 2 COOH)-; -N=N-; -R a C=CR b -, where each R a and R b , independently of one another, is a hydrogen or a C1-C12-alkyl, C1-C12-alkoxy, or C6-C18-aryl group; -(CH 2 ) m - and -(CF 2 ) m - with m being an integer from 1 to 6; an aliphatic divalent group, linear or branched, of up to 6 carbon atoms; and combinations thereof; - y1 and y2 independently vary between 0 and 50, at least one of y1 or y2 being different from 0; - R' is a bond, a heteroatom, a (CH 2 -CH 2 -O) n group with n varying from 1 to 16, a C5-C40 aryl group, a C3-C40 branched aliphatic group or a C3-C40 cycloaliphatic group; and - X is Cl, Br or I. - each R 1 is independently selected from the group consisting of a halogen, alkyl, alkenyl, alkynyl, aryl, ether, thioether, carboxylic acid, ester, amide, imide, alkali or alkaline earth metal sulfonate, alkyl sulfonate, alkali or alkaline earth metal phosphonate, alkyl phosphonate, amine and quaternary ammonium; - each i is an independently selected integer from 0 to 4; - T is selected from the group consisting of a bond, -CH 2 -; -O-; -SO 2 -; -S-; -C(O)-; -C(CH 3 ) 2 - ;-C(CF 3 ) 2 -; -C(=CCl 2 )-; -C(CH 3 )(CH 2 CH 2 COOH)-; -N=N-; -R a C=CR b -, where each R a and R b , independently of one another, is a hydrogen or a C1-C12-alkyl, C1-C12-alkoxy, or C6-C18-aryl group; -(CH 2 ) m - and -(CF 2 ) m - with m being an integer from 1 to 6; an aliphatic divalent group, linear or branched, of up to 6 carbon atoms; and combinations thereof; - y1 and y2 independently vary between 0 and 50, at least one of y1 or y2 being different from 0; - R' is a bond, a heteroatom, a (CH 2 -CH 2 -O) n group with n varying from 1 to 16, a C5-C40 aryl group, a C3-C40 branched aliphatic group or a C3-C40 cycloaliphatic group; and - R' is a bond, a heteroatom, a (CH 2 -CH 2 -O) n group with n varying from 1 to 16, a C5-C40 aryl group, a C3-C40 branched aliphatic group or a C3-C40 cycloaliphatic group; and - X is Cl, Br or I. <EOS>