Porous membranes and associated separation modules and methods

A method of making a porous membrane, the method comprising:

• dissolving a poly(phenylene ether) copolymer consisting essentially of 10 to 40 mole percent repeat units derived from 2-methyl-6-phenylphenol and 60 to 90 mole percent repeat units derived from 2,6-dimethylphenol and a hydrophilic block copolymer comprising a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) block copolymer having a number average molecular weight of 1,000 to 14,000 daltons, and comprising, based on the weight of the block copolymer, 5 to 50 weight percent, of poly(ethylene oxide) blocks;
• a poly(propylene oxide)-poly(ethylene oxide)-poly(propylene oxide) block copolymer having a number average molecular weight 500 to 12,000 daltons, and comprising, based on the weight of the block copolymer, 5 to 50 weight percent of poly(ethylene oxide) blocks;
• or a combination comprising at least one of the foregoing in a water-miscible polar aprotic solvent to form a membrane-forming composition;
• and
• phase-inverting the membrane forming-composition in a first non-solvent composition to form the porous membrane;
• wherein the weight average molecular weight of the poly(phenylene ether) copolymer is greater than or equal to 75,000 daltons and less than or equal to 500,000 daltons, measured by gel permeation chromatography against polystyrene standards.

A method of making a hollow fiber by coextrusion through a spinneret comprising an annulus and a bore, wherein the method comprises coextruding:

• a membrane-forming composition comprising a poly(phenylene ether) copolymer consisting essentially of 10 to 40 mole percent repeat units derived from 2-methyl-6-phenylphenol and 60 to 90 mole percent repeat units derived from 2,6-dimethylphenol, and a hydrophilic block copolymer comprising a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) block copolymer having a number average molecular weight of 1,000 to 14,000 daltons, and comprising, based on the weight of the block copolymer, 5 to 50 weight percent, of poly(ethylene oxide) blocks;
• a poly(propylene oxide)-poly(ethylene oxide)-poly(propylene oxide) block copolymer having a number average molecular weight 500 to 12,000 daltons, and comprising, based on the weight of the block copolymer, 5 to 50 weight percent of poly(ethylene oxide) blocks;
• or a combination comprising at least one of the foregoing dissolved in a water-miscible polar aprotic solvent, through the annulus, and
• a first non-solvent composition comprising water, a water-miscible polar aprotic solvent, or a combination comprising at least one of the foregoing, in the first non-solvent composition, through the bore,
• into a second non-solvent composition comprising water, a water-miscible polar aprotic solvent, or a combination comprising at least one of the foregoing, to form the hollow fiber;
• wherein the weight average molecular weight of the poly(phenylene ether) copolymer is greater than or equal to 75,000 daltons and less than or equal to 500,000 daltons, measured by gel permeation chromatography against polystyrene standards.