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Superhydrophilic and underwater superoleophobic membranes have recently attracted significant interest as materials for effective oil-water emulsion separation. In this work, a superwetting membrane with a spider web structured gel layer was designed for efficient oil-water separation. Biomaterial, carboxymethyl cellulose (CMC), was used as the raw material, a spider web structured gel layer was constructed on the PVDF membrane surface by heat-treatment and chemical cross-linking. The hydrophilic gel layer imparted excellent superhydrophilic and underwater superoleophobic properties to the membrane, while the special spider web structure improved the membrane mechanical stability. The fabricated membrane exhibited superhydrophilicity and underwater superoleophobicity. Among different CMC concentration-modified membranes, the M-0.5 membrane containing 0.5 wt% CMC exhibited a flux of 612 L·m−2 h−1 during dichloromethane oil-water emulsion separation, which was 4.2-fold higher than that of the pristine PVDF membrane, while the membrane showed efficient oil-water separation capacity. Additionally, the water flux recovery reached as high as 93.3 %, and oil rejection attained 99.1 %. Meanwhile, the spiderweb-structured gel layer on the membrane surface displayed good mechanical stability. In summary, this novel membrane-modification method, inspired by the spider web structure, was simple, cost effective and environmentally friendly, thereby making it promising for future preparation of highly efficient oil-water emulsion separation membranes. [Display omitted] • The natural biomaterial CMC was used as a gel material to modify the membrane. • Bionic-inspired construction of spider web-like gel layer on membranes. • The ultrathin gel layer on the membrane surface did not block the membrane pores. • The membrane exhibited separation performance and anti-fouling properties for oil-water emulsions. • The special spider web structure gel layer enhanced the membrane mechanical properties. [ABSTRACT FROM AUTHOR]

Hydrophilic polymers with low affinity for foulants were broadly utilized as functional membrane surface modifiers to mitigate fouling owing to superior hydration capability. Herein, novel hydrophilic hyperbranched poly(N-acryoyl morpholine) (HPA) synthesized through one-step RAFT polymerization was immobilized onto commercial PVDF microfiltration membrane surface using biomimetic adhesion polydopamine as an intermediate reaction platform. The surface composition and morphology of HPA decorated membranes (M-PD/HPA) were examined, demonstrating that the nano-sized HPA was facilely anchored on the membrane surface without obviously changing membrane pore size and distribution. In comparision with hydrophobic pure membrane (M-PVDF), hydrophilic and underwater superoleophobic M-PD/HPA exhibited excellent multiple defense capability toward oil, protein and bacteria due to the presence of a steric repulsive barrier of hydrated HPA layer. For model hexane-in-water emulsion separation at 0.02 MPa, permeation flux of M-PD/HPA up to 149.8 L m−2 h−1 was improved by three times and the rejection was up to 99.5%. Importantly, for the separation of complex artificial oily wastewater, relevant flux reduction of M-PD/HPA was decreased from 60.9% of M-PVDF to 36.8% and flux recovery ratio of M-PD/HPA was increased from 34.8% to 82.6%. Therefore, M-PD/HPA has a promising prospect for emulsified oil separation and water purification. Unlabelled Image • Novel hydrophilic hyperbranched Poly(N-acryoyl morpholine) (HPA) synthesized by one-pot RAFT. • HPA was immobilized on membrane surface via biomimetic adhesive chemistry. • HPA coating simultaneously enhanced surface hydrophilicity and roughness. • HPA modified membrane with enhanced separation and antifouling performance. [ABSTRACT FROM AUTHOR]