Enhanced membrane antifouling and separation performance by manipulating phase separation and surface segregation behaviors through incorporating versatile modifier

• Crosslinked copolymers were prepared by surfactant-free emulsion polymerization.
• Ultrafiltration membranes were prepared by a surface segregation method.
• The copolymers could tune both phase separation and surface segregation behaviors.
• The antifouling and separation properties of membranes were both enhanced.

In this study, the copolymers (PSn-co-PEGMAm) with crosslinked structure were synthesized and blended into polythersulfone (PES) matrix to fabricate membranes via surface segregation method. The incorporation of copolymers affected both the phase separation and surface segregation behaviors during membrane fabrication process. On one hand, the copolymers could affect the formation of nodular structure of the as-prepared membranes for increasing the size of polymeric spheres and generating a loose skin layer, which was testified by atomic force microscope (AFM) surface measurement. As a result, the water permeation flux of membranes increased from 166.9 L m−2 h−1 for the PES control membrane to 333.0 L m−2 h−1 for the PES/PS3-co-PEGMA2 membrane (with 0.80 wt% of copolymer content). On the other hand, the hydrophilic PEO segments in the copolymers could spontaneously migrate to and enrich on the membrane surface, which were demonstrated by X-ray photoelectron spectroscopy (XPS) analysis, as a result, the antifouling properties of the membranes were considerably improved. The separation performance of the membranes was evaluated by bovine serum albumin (BSA) aqueous solution as model system. With incorporation of copolymer as versatile modifier, the permeation flux of BSA aqueous solution increased and the rejection efficiency of all the membranes was 100%.

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