Tunable Permeability Research Articles

Phase-transformable metal-organic polyhedra for membrane processing and switchable gas separation

The capability of materials to interconvert between different phases provides more possibilities for controlling materials’ properties without additional chemical modification. The study of state-changing microporous materials just emerged and mainly involves the liquefication or amorphization of solid adsorbents into liquid or glass phases by adding non-porous components or sacrificing their porosity. The material featuring reversible phases with maintained porosity is, however, still challenging. Here, we synthesize metal-organic polyhedra (MOPs) that interconvert between the liquid-glass-crystal phases. The modular synthetic approach is applied to integrate the core MOP cavity that provides permanent microporosity with tethered polymers that dictate the phase transition. We showcase the processability of this material by fabricating a gas separation membrane featuring tunable permeability and selectivity by switching the state. Compared to most conventional porous membranes, the liquid MOP membrane particularly shows the selectivity for CO2 over H2 with enhanced permeability.

Tunable Negative Permittivity and Magnetic Properties of Ag/BLM Ceramic Metacomposites

Abstract Percolation composites with tunable negative permittivity have garnered significant attention due to their potential use in the field of electromagnetic interference shielding, near field amplification, antennas, and sensors. However, studies on the magnetic property at a frequency range of 100 MHz to 1 GHz are relatively scarce. The objective of this study was to examine the magnetic property and adjustable negative permittivity of silver/La-doped barium ferrite(Ag/BLM) ceramic metacomposites. In this study, Ag/BLM ceramic metacomposites with varying Ag content were prepared using a simple impregnation-calcination method. We investigate the permittivity, reactance, and permeability of Ag/BLM ceramic metacomposites at 100 MHz ~ 1GHz. The findings indicate that the percolation threshold for Ag/BLM ceramic metacomposites with x wt% is between 10 wt% and 19 wt%. When Ag content reaches 19 wt%, it creates a conductive network that generates a high number of free electrons. This leads to low-frequency plasma states and results in negative permittivity. Meanwhile, the permeability of Ag/BLM ceramic metacomposites shows the frequency dispersion due to the magnetic resonance and eddy current. Therefore, this study's findings suggest that composites with tunable negative permittivity and permeability may be developed and utilised for microwave absorption, antenna design, and wireless power transmission.

Enhancing mechanical properties of additively manufactured voronoi-based architected metamaterials via a lattice-inspired design strategy

Voronoi-based architected metamaterials have gained significant recognition as promising candidates for bone defect repair implants. However, the demanding requirements for reliable and adjustable load-bearing capacity pose challenges in applying irregular Voronoi-based architected metamaterials in implant applications. In this study, we propose a lattice-inspired design methodology for these metamaterials, enabling precise control over topologies and porosities to enhance their mechanical properties. We demonstrate the influence of unit cell topology on the printability, mechanical properties, and permeability of lattice-inspired Voronoi-based metamaterials (LIVMs) fabricated via laser powder bed fusion (LPBF) additive manufacturing. The LPBF-printed LIVMs exhibited yield strengths ranging from 3.35 to 17.59 MPa and specific energy absorption ranging from 3.81 to 14.29 J/g. Through finite element modeling and experimentation, we show that the deformation behavior of LIVMs with various topologies plays a crucial role in enhancing mechanical performance through mechanisms such as homogeneous load transfer between unit cells and multistage-contact strengthening within a unit cell. Additionally, we analyze the impact of unit cell type and porosity on the mass-transport behavior of LIVMs using computational fluid dynamics simulations. The LIVMs achieved experimental permeability values ranging from 3.88 × 10−9 to 16.83 × 10−9 m2 (consistent with trabecular bones), indicating that multiple fluid flow channels can be utilized to enhance mass transport by distributing flow pressure and increasing fluid mobility. The proposed design method effectively achieves a favorable combination of superior mechanical properties and tunable permeability in Voronoi-based architected metamaterials. These findings provide valuable theoretical guidance for the development of architected metamaterials for bone implant applications.

Liquid gated membrane with self-cleaning properties for controllable removal and multi-component separation of organic/bacterial contaminants

Membrane technology plays an important role in sustainable water treatment; however, the non-adjustable pores make it difficult to achieve precise molecular separation, and membrane fouling remains a challenge in membrane processes. Herein, a smart liquid gated membrane (LGM) was prepared by filling different lubricants in the micropores of PET track-etched membrane that was pre-treated with nano roughening and fluorination. When the pressure exceeds a critical breakthrough pressure, the liquid lined pores are formed, and higher gating liquid/water interfacial tension requires higher pressure to break through the gate. The effective pore size of LGM increases with increasing pressure. When the pressure is removed, the liquid refilling that leads to pore-closing is promoted by lower lubricant viscosity and larger effective pore size. Through the tunable permeability, controllable removal and multi-component separation of organic/bacterial contaminants can be achieved. The maximum rejection for protein approaches 94 %; as the pressure increases, three components are separated in the order of pectin, soy protein isolate and Staphylococcus aureus with maximum separation coefficient of 56.7. Due to the stable lubricant lining, LGM shows excellent self-cleaning performance with much higher flux recovery rate than the non-lubricated membranes. This liquid gated membrane has great application prospects in size-fractionated separation and product recovery.

The role of membrane filtration in wastewater treatment

AbstractWater is vital for the sustainable growth of human communities. Due to the greatest population and significant economic development, demands on water and purification have significantly risen. Classical wastewater treatment procedures have made some progress over the years in purifying effluents for disposal, but they fall lacking in the way they deeply control emerging harmful substances. The potential to reuse treated wastewater for home, agricultural, and industrial needs depends on breakthroughs in purifying technologies. One of the most recent breakthroughs to be implemented effectively in reducing contaminants to desirable levels is membrane technology. Nanofiltration, microfiltration, reverse osmosis, ultrafiltration, and membrane bioreactors are examples of widely utilized membrane processes depending on features such as size or charge. Over traditional treatment, membrane technology offers various benefits. This review article discusses a number of membrane‐related topics, including membrane categorizing, application in various fields, benefits, and drawbacks. Furthermore, offers an outlook of the filtering membranes that will be used in the future. Smart membranes have gained interest because of their tunable permeability and selectivity characteristics. Technological advancements in the media that are utilized in activated growth membrane bioreactors. Modified interfacial polymerization approaches have been investigated in addition to adsorptive ultrafiltration mixed matrix membranes to enhance the performance of the polyamide thin‐film composite and thin‐film nanocomposite membranes.

Spiropyran molecular aggregates implanted photo-responsive graphene oxide membrane with self-cleaning ability for enhanced water purification

Stimuli-responsive separation membranes with adjustable interfacial properties are highly desired for energy-efficient and sustainable water purification, owing to their exceptional antifouling capability and separation selectivity. However, the construction of highly efficient responsive membranes continues to present a substantial challenge. Herein, photo-responsive spiropyran (SP) molecular aggregates obtained via a "good-poor" solvent self-assembly strategy were implanted into lamellar graphene oxide (GO) membrane. The obtained GO/SP membrane with enriched water transport channels and enhanced hydrophilicity demonstrated superior water permeability (95.0 L h−1 m−2 bar−1). Benefiting from the reversible photoisomerization of SP molecules between the hydrophobic SP upon light irradiation and the hydrophilic zwitterionic merocyanine (MC) in dark conditions, the GO/SP membrane possessed captivating photo-response property verified by tunable water permeability and molecular rejection. Theoretical calculation revealed that the thermodynamic interface energy between bovine serum albumin (BSA) and membrane surface changed from attraction in dark conditions to repulsion under light conditions. Consequently, the water permeability of BSA-fouled membranes could recover to 96.2 % of its initial level after light irradiation, exhibiting fascinating photo-driven self-cleaning capability. The designed photo-responsive membrane with feasible membrane fouling control holds great promise for efficient water purification.

Enhancing the Accuracy and Predictability of the Oxy Field Optimizer for Dynamic Steam Allocation in the Mukhaizna Steamflood Field

Summary The main challenge for the Mukhaizna steamflood field is to allocate steam dynamically throughout the entire field, which consists of more than 3,200 wells, to obtain the most attractive reservoir performance forecast. To address this challenge, Occidental has developed a state-of-the-art closed-loop optimization solution called the Oxy Field Optimizer (OFO). The aim of this study is to enhance the accuracy, robustness, and predictability of the OFO. Recent advances include connection design, simulation stability, history-matching workflow, model predictability (blind test), and the optimizer. To improve the proxy simulator, 2D connections between wells were introduced and various strategies to handle convergence issues were implemented. The history-matching workflow has been enhanced by automating the temperature match, multistep saturation tuning, and relative permeability tuning. The results show that the implementation of gridblock material balance check, well equation check, and Not a Number (NaN) value check after line search solved multiple convergence problems. The automated temperature match process is five times faster compared with the manual process, and the automated relative permeability tuning decreased average oil mismatch by 55%. The optimizer now utilizes a parallel implementation of a novel ensemble-based optimization scheme (EnOpt) algorithm, which is twice as fast as the original implementation. These proven advances make OFO an essential tool for obtaining optimal steam allocations.

Harnessing HetHydrogel: A Universal Platform to Dropletize Single-Cell Multiomics.

A universal platform is developed for dropletizing single cell plate-based multiomic assays, consisting of three main pillars: a miniaturized open Heterogeneous Hydrogel reactor (abbreviated HetHydrogel) for multi-step biochemistry, its tunable permeability that allows Tn5 tagmentation, and single cell droplet barcoding. Through optimizing the HetHydrogel manufacturing procedure, the chemical composition, and cell permeation conditions, simultaneous high-throughput mitochondrial DNA genotyping and chromatin profiling at the single-cell level are demonstrated using a mixed-species experiment. This platform offers a powerful way to investigate the genotype-phenotype relationships of various mtDNA mutations in biological processes. The HetHydrogel platform is believed to have the potential to democratize droplet technologies, upgrading a whole range of plate-based single cell assays to high throughput format.

Functional metal-phenolic cortical cytoskeleton for artificial cells.

Cortex-like cytoskeleton, a thin layer of cross-linked cytoplasmic proteins underlying the cell membrane, plays an essential role in modulating membrane behavior and cell surface properties. However, bottom-up construction of functional cortex-like cytoskeleton in artificial cells remains a challenge. Here, we present metal-phenolic networks as artificial cortical cytoskeletons in liposome-based artificial cells. The metal-phenolic cytoskeleton-reinforced artificial cells exhibit long-term stability, enhanced resistance to a variety of harsh environments, tunable permeability, and well-controlled morphologies. We anticipate that our stable artificial cell models will stride forward to practical applications of liposome-based microsystem.

Dual stimuli pH-responsive nanofiltration membranes with tunable permeability and selectivity during separation of antitumor drug doxorubicin

This research aims to separate doxorubicin (as a pH-sensitive antitumor-drug) by dual pH-responsive-membranes (pH-Res-Mems). Since the trade-off between flux and rejection is a limiting factor for pH-Res-Mems with pH alteration, the focus of this research is to apply a novel approach i.e., inducing pH sensitivity to both membrane surface and sub-layer, to resolve the mentioned problem. To this aim, metal-oxides with Close-Gate (CG) mechanism (changing pore-size based on OH- functional-group) including copper-oxide (Cu-pH-Res) and silicon-oxide (Si-pH-Res) or metal-organic-frameworks with Open-Gate (OG) mechanism (changing pore-size based on H+ functional-group) including ZIF-8 (Zn-pH-Res) and ZIF-67 (Co-pH-Res) were added to both membrane layers simultaneously, where SurCun/SubSim and SurZnn/SubCom membranes were synthesized. Addition of Zn-pH-Res and Cu-pH-Res to the surface-layer led to improved superficial properties including hydrophilicity and roughness, while adding Co-pH-Res and Si-pH-Res to the sub-layer resulted in improvement of structural properties such as porosity and pore tortuosity. Furthermore, investigation of the pH sensitivity of membranes indicated that for the SurCu3/SubSi3 membrane, with pH reduction, the overall performance (OP) was enhanced from 2.17 to 6.40, while for the SurZn3/SubCo3 membrane, with pH elevation, OP was enhanced from 2.19 to 16.8. Eventually, the investigations revealed that the SurZn3/SubCo0 single pH-Res-Mem at neutral pH offered rejection of 89%, permeability of 4.41 LMH, and fouling of 70.4%. Meanwhile, these values for the SurZn3/SubCo3 dual pH-Res-Mem at pH= 5.5 were 95%, 21.9 LMH, and 27.2%, respectively. Overall, SurCu3/SubSi3 and SurZn3/SubCo3 membranes succeeded in 91.9% and 94.5% DOX removal from actual hospital wastewater, respectively, indicating the high-efficiency of pH-Res-Mems.

Evaluation of water desalination performances of functionalized nanoporous graphene membranes by molecular dynamics simulation

Nanoporous graphene membrane (NPGM) is a promising candidate for water desalination due to its unique features, such as chemical stability, high resistance to chlorine and fouling, excellent mechanical strength, and tunable permeability. In this work, the water desalination performances of small- and large-pore, pristine and functionalized NPGMs, with the latter containing amide, sulfonic acid, thiourea, and carbamate functional groups, were evaluated by molecular dynamics (MD) simulation. Our results indicate that pore functionalization leads to a decrease in water flow rate through the membrane. Among functionalized NPGMs, large-pore, amide-functionalized NPGM exhibited the highest water flow rate. In terms of ion rejection performance, pore functionalization resulted in partial Na+ and Cl− ion rejection by both small- and large-pore NPGMs. For small-pore, functionalized NPGMs, the rejection of Na+ and Cl− ions were higher than 98%. Comparing between the ion rejection performances of large-pore, functionalized NPGMs, the following order of Na+ ion rejection rates were observed: carbamate > sulfonic acid > thiourea > amide. The carbamate functionalization of large-pore NPGM led to about 21% and 18% Na+ and Cl− rejection, respectively. This observation is in good correlation with the smallest effective pore diameter in the carbamate-functionalized NPGM and the largest ion-carbamate interaction energies.

Engineering the Coacervate Microdroplet Interface via Polyelectrolyte and Surfactant Complexation.

Complex coacervate microdroplets, which are formed via spontaneous liquid-liquid phase separation by mixing two oppositely charged polyelectrolytes in water, have emerged as a new paradigm in the fields of origin of life, membraneless subcellular compartmentalization, bioreactors, and drug delivery. However, how to further improve its stability and enhance its selectivity in one particular coacervate system remains a challenge. By generating a membrane-like layer at the surface of coacervate microdroplets via electrostatic interactions between oppositely charged surfactants and polyelectrolytes, we here achieve tunable permeability and enhanced stability of the coacervates at the same time. Depending on the surfactants used, membrane-like layer-coated coacervate microdroplets exhibit different selectivity over solute sequestration and can promote or inhibit DNA hybridization. Our approach provides a practical tool to engineer functional bioinspired microcompartments with potential applications in the fields of controlled drug release and microreactor technology.

Double-decker-shaped phenyl-substituted silsesquioxane (DDSQ)-based nanocomposite polyimide membranes with tunable gas permeability and good aging resistance

Membrane-based gas separation technique shows great potential in CO2 elimination from natural gas and N2 enrichment from compressed air. In this study, a double-decker-shaped phenyl-substituted silsesquioxane (DDSQ)-based diamine monomer, that is, DDSQ-diamine, was synthesized and subsequently copolymerized with 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) in combination with 4,4′-oxydianiline (ODA) to fabricate a series of DDSQ-based polyimide membranes with intrinsic microporosity (PIM-PIs). The resulting membranes showcase desirable mechanical robustness, satisfactory heat resistance and good organo solubility. Owing to the inherent internal nanometer-sized cavity of DDSQ cage, DDSQ-based membranes are more nanoporous than DDSQ-free sample, accordingly exhibiting decreasing membrane density and increasing gas permeability. Among all membranes, DDSQ-25 and DDSQ-50 show more desirable overall gas separation performance, which almost achieve the 1991 Robeson upper bound. Additionally, DDSQ-25 demonstrates good plasticization resistance and CO2/CH4 mixed-gas separation properties when measured with 50:50 CO2/CH4 binary gas mixture at upstream pressure up to 20 bar. Despite physical aging at ambient conditions for 300 days, the resultant DDSQ-based polyimide membranes still have stable gas permeability and almost constant selectivity, showcasing satisfactory anti-aging characteristic.

Synthesis of a Healthy Sweetener d-Tagatose from Starch Catalyzed by Semiartificial Cell Factories.

d-Tagatose is one of the several healthy sweeteners that can be a substitute for sucrose and fructose in our daily life. Whole cell-catalyzed phosphorylation and dephosphorylation previously reported by our group afford a thermodynamic-driven strategy to achieve tagatose production directly from starch with high product yields. Nonetheless, the poor structural stability of cells and difficulty in biocatalyst recycling restrict its practical application. Herein, an efficient and stable semiartificial cell factory (SACF) was developed by constructing an organosilica network (OSN) artificial shell on the cells bearing five thermophilic enzymes to produce tagatose. The OSN artificial shell, the thickness of which can be regulated by changing the tetraethyl silicate concentration, exhibited tunable permeability and superior mechanical strength. In contrast with cells, SACFs showed a relative activity of 99.5% and an extended half-life from 33.3 to 57.8 h. Over 50% of initial activity was retained after 20 reuses. The SACFs can catalyze seven consecutive reactions with tagatose yields of over 40.7% in field applications.

Preparation of Sodium Carboxymethyl Cellulose–Chitosan Complex Membranes through Sustainable Aqueous Phase Separation

The aqueous phase separation (APS) technique has recently been introduced as one of the more sustainable methods to produce polymeric membranes. So far, almost all the APS membranes are produced on the basis of synthetic polyelectrolytes that are typically obtained from petroleum sources. In this work, we utilized natural polyelectrolytes to produce even more sustainable membranes via APS. Two natural polyelectrolytes, polyanionic sodium carboxymethyl cellulose (CMC) and polycationic chitosan (CS), were used to fabricate the polyelectrolyte complex membranes. By changing the solution pH and monomer ratio of polyelectrolytes, a desired homogeneous casting solution was prepared at pH ∼1 where CMC was uncharged. Exposing this solution to an acetate buffer coagulation bath at pH ∼5 caused CMC to acquire negative charges, leading to the formation of a polyelectrolyte complex with the positively charged CS. The structure and properties of the resultant membranes could be tuned by changing the concentration and pH of the acetate buffer. All the membranes showed an asymmetric structure with a dense top layer and porous inner structure. The membranes possessed tunable pure water permeability and were able to effectively (∼99%) remove oil droplets from an oil-in-water emulsion. This work demonstrates that natural polyelectrolytes can indeed be used to produce more sustainable APS membranes that can be directly applied for water treatment.

Freeform Membranes with Tunable Permeability in Microfluidics

AbstractMicrofluidic systems offer a multitude of advantages over classical techniques in the fields of biomedical and chemical research. Unit operations such as sample pre‐treatment, mixing, reactions, and especially separation and purification operations can be realized on microfluidic platforms enabling rapid prototyping and facile parallelization on the laboratory scale. However, the fabrication and integration of porous membranes in microfluidics poses several problems. Material development, membrane geometry, and membrane integration are three main questions to be addressed in this context. Herein, a durable and versatile method to anchor free‐form membranes with tunable microgeometry to surfaces, enabling the fabrication of stable, multi‐material microfluidic systems for different potential applications is shown. In addition, the influence of the macro‐ and microgeometry that is the shape and porosity of a membrane on key performance indicators such as diffusivity and permeation of tracer molecules is investigated. The presented characterization methods will enable a better understanding of microfluidic modules with incorporated membranes.

Robust and tunable performance of a cell-free biosensor encapsulated in lipid vesicles.

Cell-free systems have enabled the development of genetically encoded biosensors to detect a range of environmental and biological targets. Encapsulation of these systems in synthetic membranes to form artificial cells can reintroduce features of the cellular membrane, including molecular containment and selective permeability, to modulate cell-free sensing capabilities. Here, we demonstrate robust and tunable performance of a transcriptionally regulated, cell-free riboswitch encapsulated in lipid membranes, allowing the detection of fluoride, an environmentally important molecule. Sensor response can be tuned by varying membrane composition, and encapsulation protects from sensor degradation, facilitating detection in real-world samples. These sensors can detect fluoride using two types of genetically encoded outputs, enabling detection of fluoride at the Environmental Protection Agency maximum contaminant level of 0.2millimolars. This work demonstrates the capacity of bilayer membranes to confer tunable permeability to encapsulated, genetically encoded sensors and establishes the feasibility of artificial cell platforms to detect environmentally relevant small molecules.

Smart membranes for biomedical applications

Smart membranes with tunable permeability and selectivity have drawn widespread attention because of their unique biomimetic characteristics. Constructed by incorporating various stimuli-responsive materials into membrane substrates, smart membranes could self-adjust their physical/chemical properties (such as pore size and surface properties) in response to environmental signals such as temperature, pH, light, magnetic field, electric field, redox and specific ions/molecules. Such smart membranes show great prospects in biomedical applications ranging from controlled drug release to bioseparation and tissue engineering. In this review, three controlled release models realized by different designed smart membranes are emphatically introduced, and then smart membranes for biological separation and controlled cell culture are introduced and discussed respectively. At last, the existing challenges of smart membranes for biomedical applications are briefly summarized, and future research topics are suggested.

Nanoscale Polyelectrolyte Complex Vesicles from Bioinspired Peptidomimetic Homopolymers with Zwitterionic Property and Extreme Stability

The complexation of polyelectrolytes ranging from biomacromolecules to synthetic polymers offers a great opportunity to construct a new generation of hierarchical materials. Here, we report a new type of nanoscale peptidomimetic polyelectrolyte complex vesicles (PCVs), with excellent aqueous stability over time and a wide range of pH, assembled from a pair of oppositely charged bioinspired homopolypeptoids and homopoly(2-oxazoline)s. This is distinct from the traditional homopolyelectrolytes that typically form microscale-sized liquid coacervates or solids. Through a systematic study, we demonstrated that the appropriate strength of hydrogen-bonding effects arising from the polar tertiary amide groups is significantly important for the formation of the vesicle. The prepared PCVs bearing water inner lumen are capable of encapsulating hydrophilic cargo molecules with good selectivity and tunable permeability, which can facilitate the diffusion of water-soluble therapeutic molecules, proteins, and enzymes. Due to the simultaneous surface display of positive and negative charges, the vesicles show excellent stability in physiological protein solutions and low toxicity, similar to known zwitterionic polymers. These superior properties combined with the facile preparation strategy suggest that the binary PCVs could be excellent drug delivery candidates for biomedical and engineering applications.

Heterogeneous Interfaces of Magnetic CIP and Binary Dielectric Carbon-Based Material Toward High-Efficiency Microwave Attenuation

Carbon-based materials, as lightweight absorbers, have been widely applied in varied fields to counteract the adverse effects of electromagnetic waves. Nevertheless, there remain challenges in coping with the impairment of microwave absorption performance caused by the excessively high permittivity of carbon materials. Herein, carbonyl iron powder (CIP) was added to graphene oxide/carbon black (RGO-CB) composites to adjust the permittivity improving impedance matching and electromagnetic absorption properties. In this work, the RGO provides a three-dimensional structure net, which introduces circularly and variously electromagnetic loss interfaces within the RGO-CB/CIP composites. Owing to the unique architecture and synergy of the three components, the as-prepared absorber exhibits good impedance matching and gratifying microwave absorption properties. It was found that the 1:1 mixture of RGO-CB and CIP in the composite had superb impedance matching at the thicknesses of 2.6 and 2.7 mm to achieve complete X-band microwave absorption. Such excellent performance benefits from the multiple polarization provided by the heterogeneous interfaces and the ideal impedance match attributed to the tunable permeability and permittivity of this work.