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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]

Ion sieving is of great importance in a variety of applications, such as water desalination/purification, biomedical engineering and so on. The currently available techniques, based on ion size sieving by constructing membranes with nanochannels and nanopores, are still not able to achieve precise sieving of mono-/multi-valent metal ions. Here, we report on the fabrication of graphene-based membranes by constructing uniform two-dimensional (2D) nanochannels with effective channel heights of ~ 8 Å for precise and efficient sieving of mono-/multi-valent metal ions. Our membranes with uniform 2D nanochannels are built using facilely reduced graphene oxide (FRGO) nanosheets, which are controllably fabricated by avoiding the corrugation of graphene oxide (GO) nanosheets and controlling the content of oxidation groups during the reduction process. We illustrate the ability of precise sieving of mono-/multi-valent metal ions afforded by this technique by fabricating FRGO membranes with uniform 2D nanochannels, and demonstrate the excellent repeatability and long-term stability of FRGO membranes for sieving of mono-/multi-valent metal ions. [ABSTRACT FROM AUTHOR]

In this study, a universal model is developed for describing the responsive performances of both positively and negatively responsive smart gating membranes with structural and responsive parameters. The model is derived by assigning the membrane pore size change ratio before and after immobilizing responsive gates and the volume change coefficient as well as the stacking effect coefficient of responsive gates as independent dimensionless variables. The reliability and fitting precision of the proposed model have been validated by the experimental results of positively thermo-responsive and negatively Pb2+-responsive gating performances of smart gating membranes, which are prepared by immobilizing poly(N -isopropylmethacrylamide- co -4-acrylamidobenzo-18-crown-6) (PNMB) microgels in porous poly(ether sulfone) (PES) membranes as functional gates that exhibit both thermo-induced shrinking and Pb2+-induced swelling responsive characteristics. All the experimental data of both positively and negatively responsive gating performances of smart gating membranes fit well with the developed model. The proposed model provides new insights for describing and explaining the responsive gating performances of both positively and negatively responsive smart gating membranes, and offers rational guidelines for designing and fabricating smart gating membranes with desired responsive gating performances by predetermining the structural and responsive parameters of smart gates for various applications. [Display omitted] • A universal model is developed for describing responsive performances of smart gating membranes. • The model is derived by assigning structural and responsive parameters of smart membranes as variables. • Both positively and negatively responsive performances of smart membranes can be priecisely described. • Smart membranes are prepared by immobilizing dual responsive microgels in porous substrates. • Reliability and fitting precision of the model are validated by experimental data of smart membranes. [ABSTRACT FROM AUTHOR]

A facile and efficient double co-axial microfluidic device has been developed for fabricating polyethersulfone (PES) hollow fiber membranes via phase separation. The co-axial microchannels with easy center alignment consist of a cylindrical tube for bore fluid, a cylindrical tube for dope fluid and a rectangular tube for coagulation fluid. In such a double co-axial microfluidic device, three phase core-annular flows are formed for continuously fabricating hollow fibers via phase separations at the interfaces. The nascent PES hollow fibers can be extruded from the outlet of microfluidic device continuously without clogging. Typical PES hollow fiber membranes have two dense skin layers on both outer and inner surfaces, due to the phase separation at both interfaces between the dope fluid and the bore fluid as well as the coagulation fluid. The effects of fabrication conditions including microfluidic flowrates, PES concentration in dope fluid and operation temperature on the structures of microfluidic-fabricated PES hollow fiber membranes are investigated systematically. Ternary fluid-flow diagrams are created for fabricating PES hollow fiber membranes with different PES concentrations and operation temperatures. The results in this study provide valuable guidance for fabricating hollow fiber membranes with controllable microstructures and dimensions via microfluidic approach. [ABSTRACT FROM AUTHOR]

Diffusional permeability characteristics of K + -responsive membranes with grafted poly( N -isopropylacrylamide- co -acryloylamidobenzo-15-crown-5) (poly(NIPAM- co -AAB 15 C 5 )) chains in membrane pores are investigated systematically. Upon specifically recognizing K + , the grafted membrane gates dramatically switch from swollen and hydrophilic state to shrunken and hydrophobic state. The K + -responsive solute diffusion is controlled not only by the K + -triggered isothermal change of membrane pores from “closed” to “open” state but also heavily by the hydrophilic/hydrophobic switching of grafted gates. For K + -responsive diffusional permeability characteristics of the positively K + -responsive membranes, there presents a threshold value of the molecule size, which divides the solutes being promoted or restricted to diffuse across the grafted membrane upon presence of K + in environment. With size smaller than the threshold value, the solutes are promoted to diffuse across the grafted gating membrane in the K + solution compared with that in water; when the solute size is larger than the threshold value, the diffusion of solutes across the membrane is resisted in K + solution. The longer and the denser the grafted chains, the easier the membrane pores being choked with the grafted copolymer chains in the shrunken state. As a result, the larger the grafting yield of poly(NIPAM- co -AAB 15 C 5 ), the smaller the threshold value of the molecule size. The results in this study are valuable for rationally designing K + -responsive controlled release systems for biomedical purpose. [ABSTRACT FROM AUTHOR]

Organic solvent nanofiltration (OSN) as a high-efficient membrane separation technology has play an important role in chemical industrial separation, clean energy production, and high-value resources recycling, etc. Inspired by the asymmetric biological structure of Desert beetle, herein a novel kind of polymeric OSN membranes with asymmetric structure have been fabricated via fluorinated polymeric networks (FPNs) regulated interfacial polymerization. The FPNs were formed with m-phenylenediamine (MPD), dopamine (DA) and 1H,1H,2H,2H-Perfluorodecane-thiol (PFDT) via the Michael addition and Schiff-base reaction. The FPNs tailored thin-film composite membrane (FPN-TFC) with biomimetic asymmetric structure, e.g., much hydrophilic looser front surface and much hydrophobic denser rear surface, exhibits an optimum ethanol permeance ~15.7 L m−2 h−1.MPa−1 and high rejection ~99.5% for Rose Bengal (RB) dye molecules (test with 0.05 g L−1 RB ethanol solution at 25 °C under 1.5 MPa), which is almost 6 times higher than that of the conventional TFC membranes. Moreover, there is a good stability for the FPN-TFC membrane tested with different polar solvents in long-term operation process. Therefore, this work provides a guidance for the development of advanced polymeric OSN membranes with both high solvent permeability and solute selectivity, as well as good stability in OSN process, which would have broad application prospects in chemical and other industrial fields. Image 1 • Polyamide OSN membrane was fabricated via fluorinated polymeric networks regulated interfacial polymerization. • There is biomimetic asymmetric structure for the polyamide OSN membrane. • The polyamide OSN membrane exhibits both high solvent permeance and solute rejection. • The polyamide OSN membrane has good stability and anti-fouling properties in long-term OSN process. [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]

A novel three-dimensional (3D) helical membrane is developed for process intensification via generation of Dean vortices in helical membrane channel. 3D helical porous polyethersulfone membrane is fabricated by casting the membrane forming solution on the surface of 3D-printed porous substrate with a 3D helical channel structure by high-speed rotation method, and then curing by vapor-induced phase separation. The optimal helical radius and internal channel height are both 19 mm for the prepared 3D helical membranes. When the feed flowrate is higher than the minimum critical flowrate, Dean vortices can be easily generated in the 3D helical membrane channel, and thus the membrane fouling can be effectively mitigated. The ratio of average transmembrane flux of 3D helical membrane to that of conventional cylindrical membrane increases from 1.0 to ∼2.0 when the feed flowrate increases from 2.1 to 106.1 mm s−1, and from 1.0 to ∼1.9 when the feed particle concentration increases from 0 to 20 g L−1. No matter how the microstructures of particles in feed solutions vary, Dean vortices generated in 3D helical membrane channels are always efficient to diminish the particle deposition on membrane surface. The proposed strategy is highly promising for developing efficient membranes with different materials for various applications. [Display omitted] • 3D helical porous polyethersulfone membranes are developed for process intensification. • The process intensification in 3D helical membranes is achieved by generation of Dean vortices. • There exists the minimum critical flowrate for generation of Dean vortices in 3D helical membranes. • The Dean vortices are efficient to diminish the particle deposition and membrane fouling. • Membrane process intensification can be acheived by Dean vortices for treating various particles. [ABSTRACT FROM AUTHOR]

The combat against contamination by trace amounts of water and bacteria in aviation fuel remains a challenge, necessitating a comprehensive strategy. Here, a superamphophilic antimicrobial membrane is developed by featuring a stable zinc-coordinated polydopamine metallo-polymeric framework (PDA/Zn) on the skeleton of polyethylene terephthalate (PET) non-woven fabric. The formation of the PDA/Zn framework is streamlined through dopamine polymerization synchronized with metallo-ion coordination. This work delves into the intrinsic stability and superamphiphilic properties of the PDA/Zn framework, as well as systematically investigates its performance in fuel dehydration and carbophilus elimination. The resulting membrane exhibits a high gravity-driven flux and achieves a significant reduction in water content to below 10 ppm in aviation fuel, attributed to a demulsification and aggregation mechanism. Furthermore, our findings highlight the nearly complete antibacterial multifunctionality of the proposed membrane. It effectively prevents bacterial attachment at the liquid-solid interface and brings about bacterial eradication through the presence of Zn2+ ions and the mechanical puncturing effect of nanostructure cusps. This work not only advances applications in water dehydration and bacterial elimination but also pioneers opportunities for designing advanced functional membranes with multifaceted functionalities, including anti-fouling, self-cleaning, and antimicrobial properties, setting the stage for broader applications in membrane field. [Display omitted] • The high-flux nanocoating-engineered membrane could remove the water below 10 ppm in fuel. • The proposed membrane possesses an antibacterial multifunctionality: preventing attachment and mechanically killing. • The nanocoating consists of zinc-coordinated metallo-polymeric framework. • The nanocoating is prepared via one-step method of dopamine polymerization with metallo-ion coordination. • The nanocoating process excellent stability, superamphiphilic and antibacterial properties. [ABSTRACT FROM AUTHOR]

The challenge of thermal runaway in lithium-ion batteries necessitates innovative solutions to enhance their safety. In this work, a negatively thermo-responsive membrane is proposed with grafting poly (N -isopropylacrylamide) onto polydopamine-modified polypropylene (PP) membrane via the Michael addition reaction. The implementation of such smart membrane is achieved based on the upper critical solution temperature (UCST) of the PNIPAM in the electrolyte solution containing 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF 4 ]), ethylene carbonate/diethyl carbonate (EC/DEC), and lithium tetrafluoroborate (LiBF 4). The conformational transition of the PNIPAM in the electrolyte solution is intricately influenced by the competing salting-out effect of [EMIM][BF 4 ] and salting-in effect of LiBF 4. By maintaining a constant 1.0 M LiBF 4 concentration in the electrolyte solution, the UCST of the PNIPAM that is precisely adjusted according to the 45.5 wt%-50 wt% of [EMIM][BF 4 ] in the mixed EC/DEC solution provides the gating temperature. When below the gating temperature, the PNIPAM gating polymer grafted on the PP membrane remains in a shrinkable state to let the electrolyte ions shuttle feely between the electrodes. Conversely, in the event of overheating stemming from inadvertent Li-ion battery mismanagement, the PNIPAM gating polymer becomes extensible above the gating temperatures, resulting in the closure of the separator membrane. This mechanism effectively arrests the mobility of electrolyte ions, thereby contributing to the enhanced safety and security of lithium-ion batteries. The finding in this work offers valuable insights into the design and development of smart battery membranes with enhanced safety features to advance the progress of lithium-ion battery technology. [Display omitted] • The PNIPAM exhibits a UCST behavior of in EC/DEC/[EMIM][BF 4 ]/LiBF 4 solution. • The UCST is decided by the salting-out effect of [EMIM][BF 4 ] and salting-in effect of LiBF 4. • A negatively thermo-responsive membrane in organic electrolyte is prepared by grafting PNIPAM in porous substrates. • The smart membrane intelligently regulates the ion transport according to the environmental temperature. [ABSTRACT FROM AUTHOR]

Abstract: Two series of sulfonated naphthalenic polyimides containing ether and ketone linkages (SPI-KK-X and SPI-K-X) were prepared by a one-pot polymerization reaction of sulfonated diamine monomers, 1,4-bis[3-sodium sulfonate-4-(4-aminophenoxy)benzoyl]benzene or 4,4-bis[3-sodium sulfonate-4-aminophenoxy]benzophenone, with 4,4-diaminodiphenyl ether and 1,4,5,8-naphthalenetetracarboxylic dianhydride. The membranes cast from the resulting polymers had good thermal and oxidative stability, dimensional stability and mechanical properties. At 80°C, the proton conductivities of several samples, including SPI-KK-1, SPI-K-1 and SPI-K-2 were higher than 0.10S/cm, which were comparable to that of Nafion. Methanol permeabilities of the obtained polymer electrolyte membranes (PEMs) were in the range of 1.43–2.03×10−7 cm2/s, which were several times lower than that of Nafion 117. It is interesting to note that the SPI-KK-X series, having a more rigid phenyl–ketone–phenyl–ketone–phenyl moiety, had a lower dimensional swelling ratio and lower methanol permeability in comparison with the corresponding SPI-K-X series at the same level of ion exchange capacity (IEC). [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]

A novel dual pH-responsive smart gating membrane is proposed for the first time by skillfully blending poly( N,N ′-dimethylamino-2-ethyl methacrylate) (PDMAEMA) microgels into poly(ether sulfone) membrane as functional gates via liquid-induced phase separation method. The as-prepared membrane exhibits dual pH-responsive characteristics, i.e., this novel membrane is featured with both positively pH-responsive characteristics in acidic environment and negatively pH-responsive characteristics in basic environment. The mechanism of the positively pH-responsive performance is attributed to the pH-responsive volume change of PDMAEMA microgels embedded in the membrane, while that of the negatively pH-responsive performance is originated from the pH-responsive hydrophobicity and stiffness of the microgels. As a result, the permeability of this novel membrane is increased at first and then decreased with increasing the environmental pH value. The dual pH-responsive property of the prepared membrane is reversible and repeatable. The dual pH-responsive membrane proposed in this study provides a novel gating mode for design and development of pH-responsive smart membranes, which is highly potential for myriad applications, such as sewage treatments, sensors, controlled release of drugs and so on. [ABSTRACT FROM AUTHOR]

The preparation of poly(vinylidene fluoride) (PVDF) membranes with high mechanical strength via vapor-induced phase separation (VIPS) is still a great challenge. In this study, high strength PVDF membranes with cellular pore structure are successfully prepared by comprehensively regulating the process parameters such as the dissolution temperature ( T d ), vapor temperature ( T v ) and exposure time ( t ) during the VIPS process, as well as the membrane-forming parameter i.e. mass fraction of PVDF polymer. The effects of these parameters on microstructure and performances of the PVDF membranes are systematically investigated. In the investigated ranges of t from 0.67min to 20 min, the membranes with cellular structure are obtained at both elevated T d and T v of 65 °C, relative humidity of 70%RH and mass fraction of 15 wt% PVDF. All the PVDF membranes with cellular structure prepared at elevated T d and T v of 65 °C exhibit high mechanical properties, and the tensile stress at break ( σ * ) and tensile strain are higher than 2.5 MPa and 15%, respectively. The PVDF membrane prepared at t of 0.5 min has a critical structure and shows the maximum σ * of 4.0 MPa and tensile strain of 33%, respectively. It is expected that the results provide a valuable guidance for the design and fabrication of membranes from semi-crystalline polymer with desirable performances. [ABSTRACT FROM AUTHOR]

Smart gating membranes with in situ assembled poly( N -isopropylacrylamide) (PNIPAM) nanogels as gates are successfully prepared via vapor-induced phase separation (VIPS) with different exposure time periods, temperatures and relative humidities of the water vapor. Effects of the fabrication conditions on microstructures as well as thermo-responsive and mechanical performances of the membranes are investigated. Both the membrane microstructure and the movement of blended PNIPAM nanogels in the membrane forming solution can be controlled by adjusting the fabrication conditions. With increasing the exposure time, the membrane microstructure undergoes a transition from typical liquid-induced phase separation (LIPS) structure (unsymmetrical finger-like porous structure) to typical VIPS structure (symmetric cellular-like porous structure). The critical time periods for the microstructure transition of membranes prepared with vapor temperature and relative humidity of 25 °C/90%, 25 °C/70% and15 °C/70% are about 1.5 min, 2 min and 10 min respectively. The performances of membranes are heavily dependent on the microstructures. The membranes with unsymmetrical finger-like porous structures show large thermo-responsive factor ( R 39/20 , the ratio of water flux at 39 °C to that at 20 °C), with the maximum R 39/20 value being 43.2. All the membranes with symmetric cellular-like porous structures exhibit strong mechanical property and large water flux at 39 °C, which is higher than the volume phase transition temperature (VPTT) of PNIPAM nanogels. The results provide valuable guidance for rational design and fabrication of smart gating membranes with desirable performances. [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]

Abstract: pH-responsive poly(ether sulfone) (PES) composite membranes blended with amphiphilic polystyrene-block-poly(acrylic acid) (PS-b-PAA) diblock copolymers are fabricated through simple phase inversion in water. The anchor block PS has a lower surface tension than that of PES, which is beneficial to anchor the PS block near the membrane pore surfaces. Modification of membrane matrix surface including membrane surface and pore surface by PAA chains is achieved by surface-segregation of PS-b-PAA copolymers, and confirmed by water contact angle measurement on membrane surface and confocal laser scanning microscopy characterization of membrane cross-section. The effects of the blended PS-b-PAA copolymers on the microstructures and pH-responsive characteristics of the PES composite membranes are investigated systematically. The hydraulic permeation results show that the pH-responsive characteristics of composite membranes blended with PS-b-PAA copolymers are proven to be significant, fast, reversible and durable with pH switching between 3 and 8. FITC-dextran sieving experiments of a PS-b-PAA blended composite membrane at ambient pH values of 3 and 8 show 28% and 90% rejection of 70kDa solute, respectively. At pH=3 (pK a ), the membrane pores are in “closed” state due to the swollen conformation of the PAA chains. The results provide valuable guidance for fabricating stimuli-responsive membranes by blending amphiphilic block copolymers. [Copyright &y& Elsevier]

A novel method based on capsule membranes encapsulated with smart nanogels is successfully developed for facilely detecting trace lead(II) (Pb2+) ions, which are hazardous to both human health and the environment because of their toxicity. The capsule membrane system is composed of a semi-permeable calcium alginate membrane and encapsulated poly(N -isopropylacrylamide- co -acryloylamidobenzo-18-crown-6) (PNB) nanogels. The semi-permeable membrane allows Pb2+ ions and water to pass through quickly, but rejects the encapsulated nanogels and polymers totally. As soon as Pb2+ ions appear in the aqueous environment and enter into the capsule, they can be specifically recognized by encapsulated PNB nanogels via forming 18-crown-6/Pb2+ complexes that cause a Pb2+-induced phase transition of PNB nanogels from hydrophobic to hydrophilic state. As a result, the osmotic pressure inside the capsule membrane increases remarkably, and thus the elastic capsule membrane isothermally swells upon the presence of Pb2+ ions in the environmental aqueous solution. The Pb2+-induced swelling degree of the capsule membrane is dependent on the concentration of Pb2+ ions ([Pb2+]) in water. Thus, the [Pb2+] value in water is able to be easily detected by directly measuring the Pb2+-induced isothermal swelling ratio of the capsule membrane, which we demonstrate by using 15 prepared capsule membranes arranged in a line. The Pb2+-induced swelling ratios of the capsule membrane groups are easily observed with the naked eye, and the detection limit of the [Pb2+] in water is 10-9 mol L-1. Such a proposed method provides an easy and efficient strategy for facile detection of trace threat analytes in water. Image 1 ◆ Facile detection of trace Pb2+ ions is achieved using capsule membranes encapsulated with smart nanogels. ◆ The capsule membranes are featured with Pb2+-induced isothermal swelling property. ◆ The capsule membranes can be used to detect trace Pb2+ ions in water with the naked eye. ◆ The capsule membranes can efficiently detect Pb2+ ions with a limit of detection as low as 10-9 mol/L. [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]