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Abstract A novel smart membrane with ion-recognizable nanogels as gates on interconnected pores is developed for simple and rapid detection of trace lead(II) ions in water. The membrane is prepared via one-step vapor-induced phase separation (VIPS) method, and featured with interconnected porous structure and Pb2+-responsive poly(N -isopropylacrylamide- co -benzo-18-crown-6-acrylamide) (PNB) nanogels on polyethersulfone (PES) membrane pore surfaces as gates. Afforded by such a unique architecture, both high flux and significant responsive characteristics are achieved. With the proposed strategy, the nanogels are fixed onto the membrane pore surfaces during the formation of interconnected porous structure; thus, the immobilization of nanogels onto the membrane pore surfaces does not result in the decrease of pore sizes. The water fluxes of fabricated membranes could be even higher than 6000 kg m−2 h−1 driven by the static pressure of 20 cm water column under gravity at 34 °C, because of the three-dimensionally interconnected porous structures. Due to high sensitivity and selectivity of PNB nanogels on the membrane pore surfaces in response to Pb2+ ions, the fabricated membranes can efficiently detect Pb2+ ions with a limit of detection as low as 10−9 mol/L. With the proposed novel membrane, rapid detection of trace lead(II) ions in water can be easily achieved by simply monitoring the trans-membrane flux change in a gravity-driven membrane module device, which is highly potential and promising in real-time and easy-to-popularize monitoring of drinking water safety and may expand the scope of applications of facile detection techniques. Graphical abstract fx1 Highlights • A novel membrane is fabricated with ion-recognizable nanogels as gates on interconnected pores. • The membrane is featured with both high flux and significant responsive characteristics. • The membrane can be used to detect trace lead(II) ions in water with a gravity-driven device. • The membrane can efficiently detect Pb2+ ions with a limit of detection as low as 10−9 mol/L. [ABSTRACT FROM AUTHOR]

Abstract A novel composite catalytic membrane is developed by blending silicon oxide coated ferroferric oxide (Fe 3 O 4 @SiO 2) nanoparticles in polyether sulfone (PES) membrane as Fenton-like catalysts via liquid-induced phase separation (LIPS) method. By introducing Fe 3 O 4 @SiO 2 nanoparticles in PES membrane matrix, the surface hydrophilicity, porosity and mean pore diameter of as-prepared composite catalytic membranes are improved due to the hydrophilic nature of the SiO 2 coating layer on the Fe 3 O 4 @SiO 2 nanoparticles. The as-fabricated catalytic membrane can filter large particles above ~100 nm and shows a high water flux of 2084 kg m−2 h−1 under 0.1 MPa. Importantly, the composite catalytic membrane shows efficient catalytic performance and satisfactory stability in the degradation of organic pollutants based on the Fenton-like reaction mechanism. The proposed strategy for membrane fabrication and the experimental results in this study provide valuable guidance for developing high-flux catalytic membranes with efficient catalytic performances for treatment of industrial and municipal wastewater. Graphical abstract fx1 Highlights • High-flux efficient catalytic membranes are developed for degradation of organic pollutants. • The membranes are fabricated by blending Fe 3 O 4 @SiO 2 nanoparticles in PES via LIPS. • Porous microstructures are formed between nanoparticles and membrane matrix during LIPS. • The membranes exhibit high flux, efficient catalytic performance and satisfactory stability. [ABSTRACT FROM AUTHOR]

A novel β -cyclodextrin (β -CD) modified graphene oxide (CDGO) membrane with large adsorption capacity and high flux is developed for efficient removal of bisphenol A (BPA), which is an environmental endocrine disruptor that can affect human health. The CDGO membranes are fabricated by stacking CDGO nanosheets on porous substrates via vacuum filtration, and the CDGO nanosheets are fabricated by chemically grafting β -CD molecules onto both sides of GO nanosheets. Because β -CD molecules can form stable complexes with BPA molecules through host-guest recognition, the proposed CDGO membranes are featured with high efficiency for BPA removal. The water fluxes through CDGO membranes increase linearly with increasing the operating pressure, which confirms the CDGO membrane structures are stable during operations. With BPA rejection efficiency of about 100%, the fluxes of our CDGO membranes are one or two order of magnitudes higher than those of the RO and NF membranes previously used for BPA removal. The BPA adsorption capacities of our CDGO membranes are several times higher than those of the affinity membranes previously used for BPA removal, due to the high grafting density of β -CD molecules on both sides of CDGO nanosheets, the enormous surface areas of CDGO nanosheets and the winding 2D nanochannels in CDGO membranes. Furthermore, the CDGO membranes can be regenerated easily by washing with ethanol, and the BPA removal efficiency can be recovered back to nearly 100% even after several repeated running cycles. The proposed membranes with high flux and large adsorption capacity are highly promising in applications in the field of water treatments and molecular separations. Image 1 • A novel β -CD-modified graphene oxide membrane is developed for removal of bisphenol A from water. • The fabricated membrane is featured with both large adsorption capacity and high flux. • The membrane microstructure is stable during operations under different operation pressures. • The membrane can be easily regenerated by washing with ethanol. [ABSTRACT FROM AUTHOR]

Facilitated transport of K+ ions through membranes is of great significance in both science and technology for the efficient and selective separation of potassium ions. Here, a novel membrane with ion-recognizable copolymers in graphene-based nanochannels is developed for facilitated transport of potassium ions. The poly(N -isopropylacrylamide- co -benzo-15-crown-5-acrylamide) (PNB) copolymers are fixed in the lamellate spacings between the partially reduced graphene oxide (prGO) nanosheets. The K+ permeability of the fabricated prGO-PNB membrane remarkably increases at around the lower critical solution temperature (LCST) of the PNB copolymer, because of the dynamic complexation between B15C5 units and K+ ions at around the LCST. The selectivity of K+/Na+ increases with increasing the content of PNB copolymers in the membrane. The proposed membrane shows good stability in water and K+ separation performance. Due to the uniform channels and facilitated transport mechanism of the prGO-PNB membrane, the comprehensive performance of selectivity and permeability of the K+ ions is better than that of previously reported polymer-based nanofiltration membranes, polymer-based facilitated transport membranes and graphene-based membranes. The proposed strategy of this prGO-PNB membrane that combining graphene-based sheets as "skeleton" and substance-recognizable copolymers as "facilitators" is also applicable to fabricate membranes for facilitated transport of other ions or molecules. Image 1 • A novel membrane is developed for facilitated transport of potassium ions. • The membrane is fabricated with ion-recognizable copolymers in graphene-based nanochannels. • The facilitated transport of K+ ions through the membrane is achieved with the help of crown ethers. • The selectivity of K+/Na+ increases with increasing the content of copolymers in the membrane. [ABSTRACT FROM AUTHOR]

The hydrophilicity of smart additives thermodynamically and kinetically affects the degree and velocity of the phase separation of casting solution, together with their distribution on the membranes, which ultimately affects the microstructure and properties of smart membrane. However, the reasonable design and successful preparation of additives with different hydrophilicity, as well as the observation of their migration during membrane formation process and final distribution on/in the membranes remain challenges. The three kinds of thermo-responsive submicrogels with similar chemical structures and different hydrophilicity were successfully fabricated and blended into poly(ether sulfone) (PES) as functional gates to prepare smart membranes via vapor-induced phase separation (VIPS). The hydrophilicity of poly(N - n -propylacrylamide) (PNN), poly(N -isopropylacrylamide) (PNI) and poly(N -isopropylmethacrylamide) (PNM) submicrogels were quantitively measured; their diameters and thermo-responsive factors in water were similar. Moreover, the effects of the hydrophilicity of submicrogels on the microstructures and properties of as-prepared smart membranes were systematically investigated and the results were elucidated in principle. The results showed the velocity of phase separation of casting solution, the pore size of membranes and the number of submicrogels distributed on membranes increased whereas the stability of submicrogels on membranes decreased with the enhancement of hydrophilicity of submicrogels. The membrane blended with PNI submicrogels with optimal hydrophilicity, which was provided with both a large number of submicrogels stably distributed on the membrane pores as smart gates and appropriate pore size, exhibited excellent permeability and thermo-responsiveness. The maximum water flux through this membrane was 26271 kg m−2 h−1 bar−1, and its maximum normalized thermo-responsive coefficient N value reached to 28.7. The results will provide valuable guidance for understanding the mechanism of phase separation and further development of smart membranes with satisfactory performances. Image 1 • Smart membranes blending different hydrophilic submicrogels are prepared via VIPS. • The hydrophilicity of different submicrogels are quantitively measured. • The velocity of phase separation speeds up by enhancing the hydrophilicity. • The pore size of membrane is enlarged as the submicrogels hydrophilicity increasing. • The membrane blended with PNI submicrogels exhibits the optimal properties. [ABSTRACT FROM AUTHOR]

Ca-alginate/protamine/silica (APSi) hybrid capsule membranes with pH-responsive controlled release characteristics are successfully prepared by combining co-extrusion minifludics, adsorption and biosilicification under different pH conditions from 3 to 7. The microstructures of the prepared capsule membranes are characterized by optical photography, CLSM and SEM. The pH-responsive permeability of APSi hybrid capsule membranes is controlled by the electrostatic interactions between Ca-alginate networks and protamine molecules. Four kinds of solute molecules with different molecular weights including methylene blue, VB 12 , 4 kDa and 10 kDa FITC-dextran molecules are selected as solute molecules to comparatively study the diffusional permeability characteristics of solutes across APSi hybrid capsule membranes. The results show that, for the solutes with suitable molecule sizes such as VB 12 and 4 kDa FITC-dextran, the diffusional permeabilities across the capsule membranes at pH 4 are lower than those at pH 5; however, for the solutes with too small molecule size such as methylene blue or too large molecule size such as 10 kDa FITC-dextran, the diffusional permeabilities across the capsule membranes at pH 4 are very close to those at pH 5. The results in this study provide valuable guidance for fabrication and application of APSi capsule membranes in the various fields including controlled release of drugs and immobilization of enzymes and so on. [ABSTRACT FROM AUTHOR]

Antifouling poly(ether sulfone) (PES) composite membranes with novel bi-continuous porous structures, high fluxes and hydrophilic surfaces are successfully prepared by simultaneously manipulating the migration of amphiphilic three-block polymer poly(ethylene glycol)- block -poly(propylene glycol)- block -poly(ethylene glycol) (Pluronic® F127) to the membrane surfaces and the microstructures of membranes by vapor-induced phase separation (VIPS) method. Effects of the additive mass ratios of Pluronic® F127 to PES and VIPS process parameters, including the dissolution and vapor temperature (T), the relative humidity of vapor (RH) and the exposure time to vapor (t), on microstructures of membranes and the surface hydrophilicity of membranes are systematically investigated. When the additive mass ratio of Pluronic® F127 to PES is 100%, PES/Pluronic® F127 composite membranes with bi-continuous porous structure across the full cross-section can be easily fabricated. For the composite membranes with additive mass ratio of 100%, when t = 1 min, the water contact angles of membranes decrease remarkably when the temperature increases from T = 25 °C to T = 40 °C. For the PES/Pluronic® F127 composite membranes prepared via VIPS method with T = 25 °C, RH = 70% and t = 20 min, the water contact angle is as low as 34.5°, the water flux is as high as 236512 L m−2 h−1 bar−1 and the static adsorption amount of bovine serum albumin (BSA) is only 4.6 μg cm−2. Valuable guidance is presented in this study about the design and fabrication of antifouling membranes with high flux and hydrophilic surfaces. Image 1 • Composite membranes with bi-continuous porous structures and hydrophilic surfaces are fabricated. • The membranes are featured with both high fluxes and antifouling properties. • The membranes are prepared via VIPS by blending Pluronic F127 into PES matrix. • Microstructures of membranes can be controlled effectively by adjusting VIPS conditions. [ABSTRACT FROM AUTHOR]

In this paper, chitosan microcapsules with stable nano-membranes for controlled release of drugs are prepared by a simple one-step microfluidic strategy from oil-in-water (O/W) single emulsion templates. The ultrathin membranes of microcapsules are formed at the interface of the O/W emulsion droplets via the interfacial reaction between chitosan in aqueous phase and terephthalaldehyde in oil core. The membrane thickness can be effectively controlled within 10 nm and accurately regulated at nanoscale from 2.8 nm to 8.0 nm by adjusting the crosslinking time, concentrations of reactant and viscosity of aqueous solution. Among these factors, the membrane thickness is more susceptible to the viscosity of aqueous phase. The stability of the nano-membranes is quite good, which makes the microcapsules exhibit excellent structure integrity during 150 days. Using tea tree oil (TTO) as the model drug, the prepared chitosan microcapsules with nano-membranes show low mass transfer resistance and rapid drug release. The cumulative release rate of TTO from chitosan microcapsules with membrane thickness of 3.1 nm and 4.3 nm reach to 76.1% and 56.6% within 10 h, respectively. The drug release behaviors from the chitosan microcapsules are directly related to the thickness of the capsule membranes, and therefore can also be finely controlled. The thinner the capsule membrane is, the faster the drug release. The initial TTO release rate doubles as the membrane thickness decreases from 4.3 nm to 3.1 nm. In addition, because no surfactant is used in the whole preparation process, the prepared chitosan microcapsules present satisfactory biocompatibility. The results provide valuable guidance for designing and fabricating polymeric microcapsule membranes with controllable nanoscale thickness to enhance their performances in biological and medical applications. • Chitosan microcapsule membranes with controllable nanoscale thickness are developed by a simple microfluidic strategy. • The thickness of capsule membranes can be controlled within 10 nm and accurately regulated at nanoscale. • Drug release behaviors from chitosan microcapsules with nano-membranes can be finely controlled. • The nano-membranes of chitosan microcapsules present both stability and good biocompatibility. [ABSTRACT FROM AUTHOR]