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Although many methods have been investigated to enhance the anti-fouling and hemocompatility of polymeric membranes, developing simplified and high-efficiency strategies to synthesize low-fouling and hemocompatible membranes for safe blood purification remains a huge challenge. Herein, we proposed a facile and straightforward approach to solve the aforementioned problems. Firstly, poly (glycidyl methacrylate) (PGMA) was incorporated into polyethersulfone (PES) membranes via a combination of an in-situ crosslinking polymerization and the phase inversion method. Then, poly (acrylic acid-co-2-acrylanmido-2- methylpropanesulfonic acid) (PAA-AMPS) was covalently coated onto the PES membrane surfaces via an in-situ ring-opening reaction between the PAA and PGMA by simply immersing the membranes into the PAA-AMPS solution. Compared to pristine PES membrane, the protein adsorption amount of the modified membranes reduced; the flux recovery ratio and the resistance to blood cell and bacteria adhesion significantly increased. In addition, the hemocompatibility of the modified membranes was significantly improved, as indicated by the prolongation of the activated partial thromboplastin time and thrombin time of PES-based membranes by 157% and 584% respectively. The proposed simple and high-efficient strategy in this study might be a powerful tool to fabricate polymeric membranes with various and desired functions.

Ultrafiltration membranes are usually used to remove organic pollutants. However, the organic contaminants trapped in the membrane pores and on the membrane surface would limit the reuse of membranes. In this study, polyacrylic acid grafted polyethersulfone membrane was prepared; CdS was then generated in-situ on the membrane surface by subsequently immersing the membrane in Cd2+ and S2− solutions to fabricate photocatalytic composite membranes. Scanning electron microscopy and X-ray photonic energy spectroscopy revealed that the generated CdS were uniformly deposited on the surface of the membrane. The obtained membrane could effectively chemisorb rhodamine B (RhB) dye in dark, and show good photocatalytic degradation performance for RhB under visible irradiation. Meanwhile, the received membranes exhibited enhanced photocatalytic degradation performance compared with the membrane prepared by blending doping method, and displayed better removal performance (77.8 %) in the pH = 7 and low concentration (10 mg/L) RhB solution. Moreover, the degradation and removal ratio could still be stable at over 70 % after 3 cycles. In addition to degrading RhB, the composite membrane also exhibited good photocatalytic degradation for antibiotic organic pollutants. Then, free radical capture experiments showed that the photocatalytic degradation of the membrane was mainly derived from the superoxide anion free radicals. Besides, the prepared membrane also exhibited excellent RhB rejection and fast photocatalytic self-cleaning performances under visible light. Thereby, the photocatalytic composite membrane effectively solved the problem of the easy fouling of ultrafiltration membrane, and showed high potential applications in wastewater remediation.

A series of poly(ionic liquid)s (PILs) modified polyethersulfone membranes were fabricated via an in-situ cross-linking copolymerization method. Due to the positive charge and ion-exchange properties of the PILs, the membranes showed anion species and strength responsive behaviors. The morphologies and chemical compositions of the membranes were characterized by scanning electron microscope and X-ray photoelectron spectroscopy. The anion species and strength responsive properties were investigated by measuring the fluxes of the membranes with various anion species and concentrations of salt solutions. The anion strength response of the membranes was positive, and the responsive coefficient of the membranes (the ratio of the salt water flux to pure water flux) could reach 26 times when responded to the stimulus of NaCl aqueous solution; the cation species and concentrations had barely influence on the responsive behavior. Meanwhile, the membranes were responded to both anion species (including PF6−, BF4− and SCN-) and their strength: the pure water fluxes and the morphologies of the modified membranes changed associated with different types of anions, and the membranes after ion-exchanging also showed obvious anion strength responsive behaviors to the corresponding salt solutions. The facile design of anion-responsive membranes via in-situ cross-linking polymerization opens up a new route to fabricate “intelligent” membranes for ion-recognizable chemical/biomedical separations and purifications.

Redox-responsive materials have attracted much attention, and redox-responsive membrane is strongly desired since enormous numbers of redox reactions carry out in living systems. Herein, a novel polymeric membrane with redox-resposive hydraulic permeability is fabricated by introducing a reversible redox-responsive system based on the host–guest complex between ferrocene (Fc) and β-cyclodextrin (β-CD) into polyethersulfone (PES) membrane. As the result of reversible redox-responsive formation or deformation of the complex, the water flux for the membrane with 18.3 wt% redox-responsive materials was 270 mL/m 2 mmHg h in original state, while increased to 1022 mL/m 2 mmHg h in oxidation state and decreased to 538 mL/m 2 mmHg h in reduction state. In addition, the results of water contact angle, surface zeta potential and the gas flow/liquid displacement confirmed that the origin of the redox-responsive hydraulic permeability were the change of the pore size and porosity for the modified membranes. The redox-responsive membranes have great potential to be utilized in the fields of chemical detection, drug delivery, biological treatments and so on.

In this paper, the characters of hydrodynamic permeability, surface property, and blood compatibility of polydopamine (PDA) coated polyethersulfone (PES) ultrafiltration (UF) membranes were investigated in detail. We presented a general protocol to improve the hydrodynamic permeability and blood compatibility of PES UF membranes by a simple biomimetic strategy. The chemical structure and surface morphology of the PDA coated membranes were studied in detail; meanwhile, the influence of the coated PDA nano-layer on water contact angle and water flux of the modified membranes was investigated. It was found that the water flux of the pure PES membrane decreased dramatically, approach to 0 ml/(m2 h mmHg), after a few hours of PDA coating. To avoid the dramatic decline of water flux, the method of pre-adding pore-forming reagent was taken to fabricate the PDA coated PES membranes with tunable water flux. Moreover, the anti-fouling property, platelet adhesion, and blood coagulation time of the PDA modified PES membranes were studied, and the results indicated that the PDA modified PES UF membranes showed enhanced blood compatibility.

Citric acid, a widely used anticoagulant, was grafted onto polyurethane through a two-step solution polymerization. The novel synthesized polymer can be directly blended with polyethersulfone (PES) to prepare membranes. The modified membranes showed lower protein (bovine serum albumin, BSA; bovine serum fibrinogen, BFG) adsorption and suppressed platelet adhesion. Due to the binding of calcium ions in blood, the modified membranes effectively prolonged the activated partial thromboplastin time (APTT), prothrombin time (PT), plasma recalcification time (PRT) and the whole blood clotting time (WBCT). Furthermore, the modified membranes showed good cytocompatibility, and the surfaces promoted hepatocyte adhesion and proliferation compared to pure PES membrane. These results indicated that the surface modification by blending citric acid grafted polyurethane provided practical application of the membranes with good biocompatibility, especially the anticoagulant property; and the membranes could be used in blood purification fields, such as hemodialysis and bioaritificial liver assist devices.

This work presents a detailed study on the pH sensitivity of polyethersulfone (PES) hollow fiber membrane (HFM) modified by blending an amphiphilic terpolymer poly(styrene–acrylic acid–N-vinylpyrrolidone) (P(St–AA–NVP)), the HFM exhibits a pH-responsive behavior with very large water flux change as the pH value change, from nearly 38.64 to 0.64 ml/(m 2 h mmHg). Meanwhile, the influence of the occurred macro- and micro-phase separation on water contact angle, pH sensitivity, and anti-fouling property was investigated. X-ray photoelectron spectroscopy analysis revealed the enrichment of the hydrophilic segments of the terpolymer at the membrane surface. A rough surface resulted from the poor miscibility of the blend was observed, and it was proved that the phase separation would increase the pH sensitivity. Furthermore, the ultrafiltration experiments indicated that the phase separation had great effect on the pure water flux but little influence on the protein anti-fouling property after the blending of the terpolymer; and the modified membrane showed good protein anti-fouling property.

The present methodology provides a simple approach to prepare semi-interpenetrating network (semi-IPN) polymeric nanoparticles for the modification of polyethersulfone (PES) membranes. The PES/poly (N-vinyl pyrrolidinone) (PVP) semi-IPN nanoparticles were synthesized by cross-linking VP on PES chains via solution polymerization; the size of the nanoparticles ranged from 38 to 820 nm determined by dynamic light scattering (DLS), scanning electron microscope (SEM) and transmission electron microscope (TEM). The polymeric nanoparticles could be directly used to prepare membranes, and the membranes were characterized by SEM, elemental analysis etc. The water contact angles of the PES membranes decreased from 74° to 53°, and the adsorbed protein amount decreased from 9.5 μg/cm 2 to 0.7 μg/cm 2 ; meanwhile the water flux and protein anti-fouling property of the membranes increased significantly. The activated partial thrombin time (APTT) of the modified membrane was prolonged. All these results indicated the hydrophilicity and the blood compatibility of the modified PES membranes were improved.

Polyethersulfone (PES) membrane was modified by blending with a copolymer of acrylonitrile (AN) and acrylic acid (AA), followed by grafting bovine serum albumin (BSA) onto the surface of the membrane. The PES and PAN-AA blending membranes were prepared through spin coating coupled with a liquid–liquid phase separation technique. The Micro BCA™ protein assay, XPS and FTIR/ATR analysis confirmed that BSA was successfully grafted onto the surface of the membranes. The pre-activated carboxyl groups of the copolymer and the amino groups of the protein contributed to the formation of BSA-PES membrane conjugates. The water contact angle, protein adsorption and platelet adhesion were obviously decreased after grafting BSA onto the membrane surface, meanwhile the water flux of the membrane was significantly increased. All these results indicated that the hydrophilicity and blood compatibility of the modified PES membranes were improved.