A microporous polyamide or polysulfone membrane comprising a single layer having - a first microporous surface; - a second microporous surface; and, - a bulk between the first microporous surface and the second microporous surface, wherein the bulk has a first charge continuous zone, a neutral charge continuous zone, and a second charge continuous zone, the continuous zones arranged generally parallel to the first and second microporous surfaces, wherein the neutral continuous zone is interposed between the first charge continuous zone and the second charge continuous zone, and wherein the first charge continuous zone and the second charge continuous zone have opposing charges; said membrane being obtainable in a method comprising (a) preparing a polymeric solution comprising a positive charge; (b) preparing a polymeric solution comprising a neutral charge; (c) preparing a polymeric solution comprising a negative charge; (d) casting the solutions sequentially on a moving support, wherein said polymeric solutions are either all polyamide solutions or all polysulfone solutions, and wherein (i) either the polymeric solution comprising the positive charge, or the polymeric solution comprising the negative charge, is cast first, forming a pre-membrane; (ii) the polymeric solution comprising the neutral charge is cast second, onto the pre-membrane; (iii) the polymeric solution comprising the positive charge or the polymeric solution comprising the negative charge that is not cast in (i) is cast third, onto the polymeric solution comprising the neutral charge; and, (e) subsequently effecting phase separation of the solutions in a nonsolvent liquid. - a first microporous surface; - a second microporous surface; and, - a bulk between the first microporous surface and the second microporous surface, wherein the bulk has a first charge continuous zone, a neutral charge continuous zone, and a second charge continuous zone, the continuous zones arranged generally parallel to the first and second microporous surfaces, wherein the neutral continuous zone is interposed between the first charge continuous zone and the second charge continuous zone, and wherein the first charge continuous zone and the second charge continuous zone have opposing charges; said membrane being obtainable in a method comprising (a) preparing a polymeric solution comprising a positive charge; (b) preparing a polymeric solution comprising a neutral charge; (c) preparing a polymeric solution comprising a negative charge; (d) casting the solutions sequentially on a moving support, wherein said polymeric solutions are either all polyamide solutions or all polysulfone solutions, and wherein (i) either the polymeric solution comprising the positive charge, or the polymeric solution comprising the negative charge, is cast first, forming a pre-membrane; (ii) the polymeric solution comprising the neutral charge is cast second, onto the pre-membrane; (iii) the polymeric solution comprising the positive charge or the polymeric solution comprising the negative charge that is not cast in (i) is cast third, onto the polymeric solution comprising the neutral charge; and, (e) subsequently effecting phase separation of the solutions in a nonsolvent liquid. (a) preparing a polymeric solution comprising a positive charge; (b) preparing a polymeric solution comprising a neutral charge; (c) preparing a polymeric solution comprising a negative charge; (d) casting the solutions sequentially on a moving support, wherein said polymeric solutions are either all polyamide solutions or all polysulfone solutions, and wherein (i) either the polymeric solution comprising the positive charge, or the polymeric solution comprising the negative charge, is cast first, forming a pre-membrane; (ii) the polymeric solution comprising the neutral charge is cast second, onto the pre-membrane; (iii) the polymeric solution comprising the positive charge or the polymeric solution comprising the negative charge that is not cast in (i) is cast third, onto the polymeric solution comprising the neutral charge; and, (i) either the polymeric solution comprising the positive charge, or the polymeric solution comprising the negative charge, is cast first, forming a pre-membrane; (ii) the polymeric solution comprising the neutral charge is cast second, onto the pre-membrane; (iii) the polymeric solution comprising the positive charge or the polymeric solution comprising the negative charge that is not cast in (i) is cast third, onto the polymeric solution comprising the neutral charge; and, (e) subsequently effecting phase separation of the solutions in a nonsolvent liquid.