HYDROPHILIC MODIFICATION OF PPESK POROUS MEMBRANES VIA AQUEOUS SURFACE-INITIATED ATOM TRANSFER RADICAL POLYMERIZATION

Hydrophilic surface modification of poly(phthalazinone ether sulfone ketone)(PPESK) porous membranes was achieved via surface-initiated atom transfer radical polymerization(ATRP) in aqueous medium.Prior to ATRP.chloromethyl groups were introduced onto PPESK main chains by chloromethylation.Chloromethvlated PPESK(CMPPESK) was fabricated into porous membrane through phase inversion technique.Hydrophilic poly(poly(ethylene glycol) methyl ether methacrylate)(P(PEGMA)) brushes were grafted from CMPPESK membrane ...

PREPARATION OF HIGH DENSITY POLYETHYLENE/POLYETHYLENE-BLOCK-POLY(ETHYLENE GLYCOL)COPOLYMER BLEND POROUS MEMBRANES VIA THERMALLY INDUCED PHASE SEPARATION PROCESS AND THEIR PROPERTIES

High density polyethylene （HDPE）/polyethylene-block-poly（ethylene glycol） （PE-b-PEG） blend porous membranes were prepared via thermally induced phase separation （TIPS） process using diphenyl ether （DPE） as diluent. The phase diagrams of HDPE/PE-b-PEG/DPE systems were determined by optical microscopy and differential scanning calorimetry （DSC）. By varying the content of PE-b-PEG, the effects of PE-b-PEG copolymer on morphology and crystalline structure of membranes were studied by scanning electron microscopy （SEM） and wide angle X-ray diffraction （WAXD）. The chemical compositions of whole membranes and surface layers were characterized by elementary analysis, Fourier transform infrared spectroscopy-attenuated total reflection （FTIR-ATR） and X-ray photoelectron spectroscopy （XPS）. Water contact angle, static protein adsorption and water flux experiments were used to evaluate the hydrophilicity, antifouling and water permeation properties of the membranes. It was found that the addition of PE-b-PEG increased the pore size of the obtained blend membranes. In the investigated range of PE-b-PEG content, the PEG blocks could not aggregate into obviously separated domains in membrane matrix. More importantly, PE-b-PEG could not only be retained stably in the membrane matrix during membrane formation, but also enrich at the membrane surface layer. Such stability and surface enrichment of PE-b-PEG endowed the blend membranes with improved hydrophilicity, protein absorption resistance and water permeation properties, which would be substantially beneficial to HDPE membranes for water treatment application.

Harvesting Microalgae Biomass Using Sulfonated Polyethersulfone(SPES)/PES Porous Membranes in Forward Osmosis Processes

This study was performed to investigate the availability of forward osmosis(FO)for microalgae harvesting using sulfonated polyethersulfone(SPES)/PES porous membranes.In FO process,porous membranes(<25.0 L m^−2 h^−1)exhibited more superior water flux than TFC FO membranes(<2.6 L m^−2 h^−1).Furthermore,the incorporation of SPES has been demonstrated to enhance membrane performance.The effects of SPES content on pore structure and separation performance were investigated.Compared with pure PES porous membranes,porous membranes with 40%SPES yielded an improved hydrophilicity and greater porosity.It exhibited two times higher water fluxes than the pure PES porous membrane.For microalgae harvesting,AL-FS mode(active layer facing the feed solution)was more favourable than AL-DS mode(active layer facing the draw solution)because less deposited microalgae on the active layer mitigate the membrane biofouling.FO operation combined with SPES/PES porous membranes is conducive to preserving microalgae cell integrity under the mild condition.In addition,FO membrane can be cleaned by a simple water rinse.Potential implications were highlighted as a sustainable method for microalgae harvesting because of no pressure input and less chemical cleaning demand.

Functional Poly(ionic liquid)Porous Membranes:From Fabrications to Advanced Applications

Polyelectrolyte porous membranes(PPMs)belong to the most interesting classes of materials,because the synergy of tunable pore sizes and charge nature of polyelectrolyte endow them with wide-ranging practical applications.However,owing to the water solu-bility and ionic nature of the polyelectrolytes,traditional polyelectrolytes are difficult to use in scalable preparation of high-quality PPMs through the well-developed industrial methods.Poly(ionic liquid)s(PIL)are a subclass of functional polyelectrolytes bearing ionic liquid groups in their repeating unites,inheriting the advantages of ionic liquids(ILs)and macromolecular architecture features.In recent years,along with rapid development of PIL materials chemistry,considerable and significant developments involving the novel preparation methods,and structure-property-function relationships of PPMs have been made.In this review,we highlight the latest discovery and proceedings of PPMs,particularly the advancements in how to tailor structures and properties of PPMs by ra-tional structure design of PILs.The formation mechanisms of various PPMs were also discussed in detail from the viewpoint of PILs molecular structures.A future perspective of the challenges and promising potential of PPMs is cast on the basis of these achieve-ments.We expect that these analyses and deductions will be useful for the design of useful PPMs and serve as a source of inspira-tion for the design of future multifunctional PPMs.

Porous catalytic membranes for CO_(2)conversion

Catalytic CO_(2)conversion has witnessed a dynamic growth in recent decades.Various materials have been applied to reduce CO_(2)into fuels and value-added chemicals.Normally,the powder-based catalysts cannot be directly utilized for CO_(2)conversion.Much attention was paid to the study of catalytic membranes in order to overcome this issue,since it is convenient for catalytic membranes to be employed in devices for practical applications.In this review,the recent research development of porous catalytic membranes for CO_(2)conversion is summarized.The preparations of representative porous catalytic membranes and their CO_(2)conversion methods,including electrocatalysis,photocatalysis,photoelectrocatalysis,thermalcatalysis and biocatalysis,are discussed in detail.This review is expected to provide deep understanding on the utilization of porous catalytic membranes for CO_(2)conversion.

Porous polybenzimidazole membranes with positive charges enable an excellent anti-fouling ability for vanadium-methylene blue flow battery

A cost-effective, high-performance and highly stable membrane has always been in intensively needed in aqueous organic-based flow batteries. Here we present a porous polybenzimidazole(PBI) membrane with positive charges that endow the membrane with a high rejection and an excellent anti-fouling ability for target organic molecule and asymmetric structure that affords a high conductivity for vanadiummethylene blue flow battery(V-MB FB). The morphologies and thickness of separating layer in particular of the porous PBI can be well adjusted by simply altering the polymer concentration in the cast solution and further afford the membrane with a controllable property in terms of both ion selectivity and ion conductivity. As a result, a V-MB FB assembled with a porous PBI membrane delivers a coulombic efficiency(CE) of 99.45% and an energy efficiency(EE) of 86.10% at a current density of 40 mA cm^(-2), which is 12% higher than that afforded by a Nafion 212 membrane. Most importantly, the V-MB FB demonstrates a methylene blue(MB) utilization of 97.55% at a theoretical capacity of 32.16 Ah L^(-1)(based on the concentration of MB in the electrolyte) because of the high ion conductivity of the membrane, which favors reducing the cost of a battery. The results suggest that the designed porous PBI membranes exhibit a very promising prospect for methylene blue-vanadium flow battery.

Catalytic bubble-free hydrogenation reduction of azo dye by porous membranes loaded with palladium nanoparticles

Catalytic bubble-free hydrogenation reduction of azo dye by porous membranes loaded with palladium （Pd） nanoparticles was studied for the first time. The effects of Pd loading, dye concentration and reuse repetitions of membranes were investigated. In reduction, the dye concentration decreased whereas the pH rose gradually. An optimal Pd loading was found. The catalytic membranes were able to be reused more than 3 times.

Porous Membranes with Special Wettabilities:Designed Fabrication and Emerging Application

Porous materials have become a burgeoning research interest in materials science because of their intrinsic porous characteristics,versatile chemical compositions,and abundant functionalities.Recently,inspired by natural superwetting surfaces originating from the cooperation of surface energy and surface geometry,porous membranes with special wettabilities are finding emerging opportunities associated with a wide variety of environmental and energy-related applications.This review will present an overview of the state-of-the-art research on the designed fabrications and applications of superwetting porous membranes based on zeolites,metal–organic frameworks(MOFs),porous organic materials(POMs),and mesoporous materials.General synthetic strategies for the fabrication of porous membranes(e.g.,hydrothermal/solvothermal crystallization,interfacial polymerization,electrospinning,etc.),and principles for tuning the wettability of porous membranes through surface energy modulation are introduced.Furthermore,their emerging applications as oil–water separation membranes,lithium-ionbattery separators,self-cleaning layers,and anticorrosion coatings are demonstrated.Finally,we emphasize on future perspectives regarding the development of superwetting porous membranes for practical applications.

Hydrogen-Bonded, Hierarchically Structured Single-Component Chiral Poly(ionic liquid) Porous Membranes: Facile Fabrication and Application in Enantioselective Separation

The development of strategies for producing welldefined chiral porous membranes for the rapid and efficient enantioseparation of racemic mixtures remains a great challenge.Herein,we introduce an innovative,simple,and easily scalable synthetic strategy to manufacture chiral porous polymer membranes(CPPMs)bearing chiral NH groups by crosslinking single-component chiral poly(ionic liquid)s(PILs)with water molecules via hydrogen(H)-bonding.

Carbon Capture from Flue Gas Based on the Combination of Non-Contact Hydrophobic Porous Ceramic Membrane and Bubbling Absorption

A hybrid system combined with a non-contact membrane and bubbling absorption is proposed to capture CO_(2) from flue gas.The non-contact way of membrane and liquid absorbent effectively avoids the reduction of gas diffusion flux through the membrane.High-porosity ceramic membranes in hybrid systems are used for gas-solid separation in fuel gas treatment.Due to the high content of H_(2)O and cement dust in the flue gas of the cement plant,the membrane is hydrophobically modified by polytetrafluoroethylene(PTFE)to improve its anti-water,anti-fouling,and self-cleaning performances.The results show that the diffusion flux of CO_(2) through the membrane is still higher than 7.0×10^(−3) mol/m^(2)s(20%CO_(2) concentration)even under the influence of water and cement dust.In addition,slaked lime selected as the absorbent is cheap and the product after bubbling absorption is nano-scale light calcium carbonate.To sum up,the hybrid system combining non-contact membrane and bubbling absorption is expected to be used to capture carbon dioxide from the flue gas of the cement plant.

Soft Template-Induced Porous Polyvinylidene Fluoride Membrane for Vanadium Flow Batteries

Vanadium flow batteries(VFBs)are considered ideal for grid-sc ale,long-duration energy storage applications owing to their decoupled output power and storage capacity,high safety,efficiency,and long cycle life.However,the widespread adoption of VFB s is hindered by the use of expensive Nafion membranes.Herein,we report a soft template-induced method to develop a porous polyvinylidene fluoride(PVDF)membrane for VFB applications.By incorporating water-soluble and flexible polyethylene glycol(PEG 400)as a soft template,we induced the aggregation of hydrophilic sulfonated poly(ether ether ketone),resulting in phase separation from the hydrophobic PVDF polymer during membrane formation.This process led to the creation of a porous PVDF membrane with controllable morphologies determined by the polyethylene glycol content in the cast solution.The optimized porous PVDF membrane enabled a stable VFB performance for 200 cycles at a current density of 80 mA/cm^(2),and the VFB exhibited a Coulombic efficiency of 95.2%and a voltage efficiency of 87.8%.These findings provide valuable insights for the development of highly stable membranes for VFB applications.

POROUS MEMBRANE TEMPLATED SYNTHESIS OF POLYMER PILLARED LAYER

The anodic porous alumina membranes with a definite pore diameter and aspect ratio were used as templates tosynthesize polymer pillared layer structures. The pillared polymer was produced in the template membrane pores, and thelayer on the template surfaces. Rigid cured epoxy resin, polystyrene and soft hydrogel were chosen to confirm themethodology. The pillars were in the form of either tubes or fibers, which were controlled by the alumina membrane pore surface wettability. The structural features were confirmed by scanning electron microscopy results.

Preparation of porous polyamide 6(PA6)membrane with copper oxide(CuO)nanoparticles selectively localized at the wall of the pores via reactive extrusion

In this study,CuO nanoparticles are pre-modified with styrene-maleic anhydride copolymers(SMAs)of different molecular weights and MAH contents.Then the pre-modified CuO nanoparticles(CuO-SMAs)are added to the PA6/SEBS(Styrene Ethylene Butylene Styrene copolymer)(40/60 wt/wt)polymer blends with a co-continuous morphology.When SMA3(MAH=8 wt%,M_(n)=250000 g/mol)is used to modify CuO nanoparticles,and the grafting degree of SMA3 on the surface of CuO reaches 2.74 wt%,90.71%of the added mCuO-SMA3 nanoparticles can be located at the interface of PA6 and SEBS.A porous PA6 membrane with CuO nanoparticles located at the pore walls can be obtained after the SEBS phase is etched with xylene.The catalytic reaction velocity constant(k)for the reduction of p-nitrophenol in NaBH_(4)solutions with the PA6/mCuO-SMA3 porous membrane can reach 1.0040 min^(-1).This work provides a feasible and straightforward method for the preparation of porous polymer membranes with functional nanoparticles located at the wall of the pores.

Ion-conducting Membranes Based on Bacterial Cellulose Nanofibers Modified by Poly(sodium acrylate-co-2-acrylamido-2-methylpropanesulfonic acid)

Green method for preparation of ion-conducting membranes(ICM) based on bacterial cellulose nanofibers(CNF) modified by a copolymer of sodium acrylate and 2-acrylamido-2-methylpropanesulfonic acid was elaborated. FTIR and NMR data confirmed grafting of polyacrylate onto cellulose surface. Formation of porous structure of the ICM was controlled by SEM and AFM. The maximal ionic conductivity of the membranes reaches 1.5 and 3.1 mS·cm^(-1)(60 ℃ and 98% relative humidity) when they are saturated with water or H_2SO_4(1 mol·L^(-1)) electrolyte,respectively. Prepared ICM was tested as a separator in a symmetrical supercapacitor with electrodes based on polyaniline hydrogel. The assembled cell demonstrate ability to operate at high current density up to 100 A·g^(-1) maintaining specific capacitance 165 F·g^(-1). Maximal specific capacitance of 289 F·g^(-1) was achieved at current density 1 A·g^(-1). Retaining of 90% of initial capacitance after 10000 of charge-discharge cycles proves high electrochemical stability of prepared ICM.

Self-Healing Hydrophilic Porous Photothermal Membranes for Durable and Highly Efficient Solar-Driven Interfacial Water Evaporation

It is highly desirable to develop a solar-driven interfacial water evaporatorwith a self-healing ability and high-efficiency water evaporation performance for water distillation and desalination;however,this process is considerably challenging.Herein,by exploiting the advantages of a self-healing hydrophilic polymer,a self-healing hydrophilic porous photothermal(SHPP)membrane was fabricated by curing a mixture of the polymer,carbon black,and NaCl,followed by removal of the NaCl from water.Since the SHPP membrane could serve as a photothermal layer and water transportation channel simultaneously,a solar-driven interfacial evaporator could be fabricated readily by assembling the SHPP membrane with polyethylene foam.We have shown that the SHPP membrane-based evaporator exhibited a water evaporation rate of 1.68 kg m^(−2) h^(−1) and an energy efficiency of 97.3%.These values are superior to those obtained using solar-driven interfacial evaporators with self-healing capability.Notably,by hydrogen bonds reformation between the fracture surfaces,the SHPP membrane could regain its structural integrity after breaking,making the SHPPmembrane-based evaporator the first to heal entirely and repeatedly from physical damage to sustain itswater evaporation capacity.Therefore,the potential of using SHPP membranes to develop stable,long-last ing,andhigh-efficiency solar-driven interfacial water evaporators is highlighted.

Nanoporous Vesicular Membranes of Amphiphilic Polymers Containing Trans/Cis Isomers

Nanoporous membranes and vesicles are interesting systems with potential in applications offering channels for material exchange.Herein,nanoporous membranes and polymersomes are developed by self-assembly of trans-and cis-stereoisomers of amphiphilic polymers.Two polymers,PEG550-TPEChol and PEG550-SS-TPE-SS-Chol,containing a central tetraphenylethene(TPE),a cholesterol(Chol),and a poly(ethylene glycol)(PEG550)are studied.

A highly stable membrane with hierarchical structure for wide pH range flow batteries

A membrane with high stability and ion conductivity in wide pH range is essential for energy storage devices.Here,we report a novel membrane with hierarchical core-shell structure,which demonstrates high stability and ion conductivity,simultaneously under a wide pH range applications.Spectral characterizations and theoretical calculation indicate that the non-solvent induces the chain segment configuration and eventually leads to polymer-polymer phase separation,thus forming hierarchical porous core-shell structure.Benefiting from this structure,an acidic vanadium flow battery(VFB)with such a membrane shows excellent performance over 400 cycles with an energy efficiency(EE)of above 81%at current density of 120 mA cm^(-2) and an alkaline zinc-iron flow battery(AZIFB)delivers a cycling stability for more than 200 cycles at 160 mA cm^(-2),along with an EE of above 82%.This paper provides a cost-effective and simple way to fabricate membranes with high performance for variety of energyrelated devices.

涉及垂直多孔膜的斜向入射波散射问题研究

Oblique surface waves incident on a fixed vertical porous membrane of various geometric configurations is analyzed here.The mixed boundary value problem is modified into easily resolvable problems by using a connection.These problems are reduced to that of solving a couple of integral equations.These integral equations are solved by a one-term or a two-term Galerkin method.The method involves a basis functions consists of simple polynomials multiplied with a suitable weight functions induced by the barrier.Coefficient of reflection and total wave energy are numerically evaluated and analyzed against various wave parameters.Enhanced reflection is found for all the four barrier configurations.

Thermo-sensitive Porous Polymer Membrane-immobilized Cellulose as a Switchable Enzyme Reactor for Tuning Its Enzymolysis via Variation Temperature

Immobilization of enzymes onto porous membranes has attracted considerable attention in recent years.However,enhancing the enzymolysis efficiency of the resulting enzyme reactors by varying the environmental conditions poses a great challenge.In this work,poly(styrene-maleic anhydride-N,N-dimethylacrylamide)was prepared and utilized to construct a thermo-sensitive porous polymer membrane-based enzyme reactor(TS-PPMER)after cellulase was immobilized onto the support by covalent bonding.The catalytic activity of the nano-reactor was evaluated by measuring the yield of the product,glucose,at different temperatures with carboxymethylcellulose as the substrate.Interestingly,the polymer chains coiled and formed numerous nano-pores at a high temperature,which induced the confine effect and greatly boosted the enzymolysis efficiency of TS-PPMER.Furthermore,the proposed TS-PPMER was applied in the hydrolysis of green plant leaves in Epipremnum aureum.This work shows great potential in obtaining biological resources by an environmentally friendly approach using smart polymer-based nano-reactors.

Fabrication of intra porous PVDF fibers and their applications for heavy metal removal,oil absorption and piezoelectric sensors

Intra porous fibrous membranes have enhanced metal ionic adsorption and oil separation abilities than those of intra nonporous fibrous membrane.In this paper,we prepared highly intra porous fibrous poly(vinylidene fluoride)(PVDF)membranes using an innovated water-mediated electrospinning approach.FTIR-ATR and XRD techniques confirmed the conversion of non-polarα-phase to polarβ-phase in electrospun membranes.The porous fibrous membrane M–16 had adsorbed oil almost 120%and metal adsorption around 15%,12%,5%,13%respectively for Pb^(2+),Cd^(2+),Cu^(2+)and Zn^(2+),which are larger than the counterpart of nonporous M–18.The nonporous fibrous membranes have better peak to peak output voltage(Vp-Vp)2 to 3 times than the porous fibrous membranes(M–16).The results show apparent potential applications in wastewater/oil spill treatment as well as piezoelectric sensors.