A method for the preparation of a membrane (m) comprising a sulfonated poly(arylene ether sulfone) polymer (sp) and a non-sulfonated poly(arylene sulfone) polymer (p)

A method for the preparation of a membrane (M), the membrane (M) comprising

• (A) a sulfonated poly(arylene ether sulfone) polymer (sP) and
• (B) a non-sulfonated poly(arylene sulfone) polymer (P),
• wherein the method comprises at least steps a) and b):
• a) providing a solution(S) which comprises the sulfonated poly(arylene ether sulfone) polymer (sP) according to component (A), the non-sulfonated poly(arylene sulfone) polymer (P) according to component (B), at least one pore forming additive (C) and at least one solvent (D), wherein the at least one pore forming additive (C) comprises poly(vinyl pyrrolidone), and
• b) separating the at least one pore forming additive (C) and the at least one solvent (D) from the solution(S) to obtain the membrane (M),
• wherein the solution(S) in step a) comprises from 0.5 to 20% by weight of the sulfonated poly(arylene ether sulfone) polymer (sP), from 0.5 to 20% by weight of the non-sulfonated poly(arylene sulfone) polymer (P), from 3 to 20% by weight of the at least one pore forming additive (C) and from 40 to 96% by weight of the at least one solvent (D), based in each case on the total weight of the solution(S), wherein the at least one pore forming additive (C) comprises in the range from 17 to 75% by weight of poly(vinyl pyrrolidone) and in the range from 25 to 83% by weight of at least one alcohol,
• and wherein the separation of the at least one pore forming additive (C) and the at least one solvent (D) from the solution(S) is carried out via a phase inversion process.

The method according to claim 23, wherein the non-sulfonated poly(arylene sulfone) polymer (P) is

• i) a poly(ether sulfone) and comprises units of formula (Ik)
• or
• ii) a polysulfone and comprises units of formula (Ia)
• or
• iii) a polyphenylene sulfone and comprises units of formula (Ig)