Achieving persistent high-flux membranes via kinetic and thermodynamic synergistic manipulation of surface segregation process

Persistent high-flux membranes were fabricated via kinetic and thermodynamic synergistic manipulation of surface segregation process. Poly (ether sulfone) (PES) was utilized as the bulk membrane material, poly (N-vinyl pyrrolidone-alt-maleic anhydride)-b-poly(styrene) (P(NVP-alt-MAH)-b-PS) with polyethylene glycol (PEG) was utilized as the precursor of surface segregation modifiers (SSMs). In casting solutions, the SSMs were in-situ synthesized through the alcoholysis reaction between the anhydride groups in P(NVP-alt-MAH)-b-PS and the hydroxyl groups in PEG, and then the membranes were fabricated with the non-solvent induced phase separation of PES and the surface segregation of the SSMs. The high mole ratio of hydrophilic/hydrophobic segments and adjustable crosslinking degree of the SSMs afforded the sufficient surface enrichment of the hydrophilic segments in the SSMs, as a result, the coverage of PEG segments on the membrane surfaces reached as high as 40.0 at%. Meanwhile, the strong interactions between the SSMs and PES and the high molecular weight of the SSMs afforded the durable surface enrichment of the SSMs, as a result, the water contact angle and the O/C ratio of the membrane surfaces were nearly unchanged after scoured by water for 30 days. Moreover, the crosslinked SSMs interfered and delayed the solidification of PES, endowing the membranes with higher porosity and bigger pore sizes. Accordingly, the membranes displayed persistent high-flux of 230 Lm(-2)h(-1)bar(-1) in ternary-circle ultrafiltration experiment.