Bioinspired catechol/APTES interlayer for constructing zwitterionic PMPC coating on PVDF membranes with superior antifouling performance

Membrane fouling significantly impairs separation performance and durability. To address this, a bioinspired intermediate layer of dopamine methacrylamide (DMA) and (3-aminopropyl)triethoxysilane (APTES) was developed to enhance the grafting of poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) onto polyvinylidene fluoride (PVDF) membranes via surface-initiated polymerization. The incorporation of this intermediate layer enabled complete surface wetting of the zwitterionic monomer MPC, increasing the availability of reactive sites and yielding a grafting ratio of 183.4 μg/cm 2 , compared to 10.3 μg/cm 2 for unmodified PVDF surfaces. Furthermore, the DMA/APTES layer may undergo cross-linking through the addition of Fe 3+ , leading to an increase in the chemical stability of the coating when exposed to extreme pH conditions. The PMPC-modified membrane (PVDF-DMA-APTES-Fe-PMPC) exhibited marked superhydrophilicity, with a static water contact angle of 16.0° that rapidly dropped to 0° within 10 s. This hydrophilic transformation significantly reduced protein adsorption, lowering bovine serum albumin (BSA) accumulation to 19.3 μg/cm 2 , in contrast to 197.5 μg/cm 2 observed on pristine PVDF. Antibacterial assays further revealed a 1.6 log 10 reduction in Escherichia coli after 12 h of incubation, indicating effective resistance to bacterial adhesion. In filtration performance, the modified membrane maintained a high pure water flux of 336.3 LMH in the first cycle, coupled with excellent antifouling durability. This study showcases a versatile approach for modifying hydrophobic polymeric membranes, highlighting their possible applications in purifying protein−wasted water.