Incorporation of cross-linked poly(AA-co-ACMO) copolymer with pH responsive and hydrophilic properties to polysulfone ultrafiltration membrane for the mitigation of fouling behaviour

N-acryloylmorpholine (ACMO), a promising fouling resistant additive with good hydrophilicity, was used to synthesize novel pH responsive hydrophilic cross-linked poly(acrylic acid-co-acryloylmorpholine) (poly(AA-co-ACMO)) copolymer via precipitation polymerization. The copolymer was directly used as an additive into the casting solution for fabrication of modified PSF membranes by phase inversion method. The successful synthesis of copolymer and membranes were confirmed by FTIR-ATR spectroscopy. The thermodynamics of the membrane formation was analysed by plotting the ternary phase diagram of poly(AA-co-ACMO)/PEG6000/PSF/NMP/H2O system. The gradual increase in dose of copolymer from 0 wt% to 1.5 wt% supports in finger-like structure and uniform pore formation mechanism in the membrane. The modified membrane showed maximum porosity, pore density and permeability with 1.5 wt% of copolymer. The CA and quantity of adsorbed BSA were decreased significantly from 59.3° and 0.12 mg/cm2 for plain membrane (M1–0.0) to 44.4° and 0.03 mg/cm2, respectively for modified membrane (M1–2.0). The modified membranes also exhibited sign of pH sensitivity and IEC compared to plain membrane. The modified membranes expressed enhanced rejection against BSA and oil-in-water (o/w) emulsion with improved fouling resistance property. Moreover, the content of acrylic acid (AA) and ACMO during synthesis of cross-linked copolymer influence the permeation behaviour of the membrane. The flux recovery ratio was increased from 0.61 (M1–0.0) to 0.92 (M1–2.0) with increase in dose of copolymer (wt%) and from 0.86 (M3–1.5) to 0.93 (M2–1.5) with increase in ACMO content in the copolymer. In general, poly(AA-co-ACMO)/PEG6000/PSF membrane may provide a potential application in separation against protein solution and o/w emulsion separation system.