Polyzwitterion grafted onto PET microfiltration membrane via surface-initiated ATRP for enhanced antifouling performance

To address the challenges of membrane fouling, we present a surface modification strategy that combines the high efficiency of surface-initiated atom transfer radical polymerization (SI-ATRP) with the excellent antifouling properties of zwitterionic polymers. A poly(St- co -VBC) macromolecular initiator was first deposited onto poly(ethylene terephthalate) (PET) microfiltration membranes, followed by the grafting of three distinct zwitterionic polymers, poly(sulfobetaine methacrylate) (PSBMA), poly(phosphorylcholine methacrylate) (PMPC), and poly(1-(3-sulfonic acid propyl)-4-vinyl pyridinium salt) (PSPV). The successful surface modification was confirmed by water contact angles (WCA) and X-ray photoelectron spectroscopy (XPS). The WCA of the three polyzwitterionic coatings were 20 ∼ 25 o , and all decreased to 0° within 5 s, indicating their rapid surface wettability. XPS analysis revealed high sulfur or phosphorus content, suggesting their high grafting densities. The modified membranes maintained stable water flux (3700–4100 L·m −2 ·h −1 ·bar −1 ), with flux recovery rates consistently above 93% and irreversible fouling rates below 6.5%. Compared to the pristine PET membrane, the polyzwitterion modified surfaces showed significantly reduced protein adsorption (≥ 83%) and bacterial adhesion (≤ 2.5%), confirming substantially enhanced antifouling performance. Among the three coatings, the antifouling efficacy followed the order: PSPV > PMPC > PSBMA. This facile and universal surface modification strategy is expected to be widely applicable in various materials and devices.