Block polymer composite membranes

A composite membrane comprising a polysulfone (Psf) and a polystyrene-b-poly(acryloyl) diblock copolymer (PS-PAX) of Formula I:

• wherein
• R1 is H, halo, OH, NH2, alkyl, alkoxy, or alkylamino;
• y is 10-1000;
• z is 10-1000;
• and
• X is a branched polyethylenimine of Formula II:
• wherein
• R2 is —C(═O)R3;
• R3 is a tethered nitrogen heterocycle of Formula III:
• wherein
• R5 is H, halo, OH, NH2, alkyl, alkoxy, or alkylamino;
• and
• n is 1-10;
• R4 is H or —C(═O)R3;
• m is 10-1000;
• wherein the weight ratio of Psf to PS-PAX is greater than 2 to 1 and less than 6 to 1;
• wherein the membrane has a network of interconnecting pores and pore openings at the surface of the membrane, the pores comprise polymer chains extending from the inner surface of the pores into the lumen of the pores, the chains comprise a segregated poly(acryloyl) moiety of the diblock copolymer, and the segregated poly(acryloyl) moiety comprises a plurality of metal ion binding groups of Formulas II and III that are capable of binding metal ions from wastewater;
• and
• wherein the diameters of the pore openings are less than about 5000 nm and the membrane has a metal ion maximum binding capacity (Q) of at least 0.4 mmol/g.