Porous Polymer Membranes Research Articles

A Comprehensive Review of Performance of Polyacrylonitrile-Based Membranes for Forward Osmosis Water Separation and Purification Process.

Polyacrylonitrile (PAN), with its unique chemical, electrical, mechanical, and thermal properties, has become a crucial acrylic polymer for the industry. This polymer has been widely used to fabricate ultrafiltration, nanofiltration, and reverse osmosis membranes for water treatment applications. However, it recently started to be used to fabricate thin-film composite (TFC) and fiber-based forward osmosis (FO) membranes at a lab scale. Phase inversion and electrospinning methods were the most utilized techniques to fabricate PAN-based FO membranes. The PAN substrate layer could function as a good support layer to create TFC and fiber membranes with excellent performance under FO process conditions by selecting the proper modification techniques. The various modification techniques used to enhance PAN-based FO performance include interfacial polymerization, layer-by-layer assembly, simple coating, and incorporating nanofillers. Thus, the fabrication and modification techniques of PAN-based porous FO membranes have been highlighted in this work. Also, the performance of these FO membranes was investigated. Finally, perspectives and potential directions for further study on PAN-based FO membranes are presented in light of the developments in this area. This review is expected to aid the scientific community in creating novel effective porous FO polymeric membranes based on PAN polymer for various water and wastewater treatment applications.

A mini‐review of polymeric porous membranes with vertically penetrative pores

AbstractMembrane separation technology plays a pivotal role in modern industry and scientific research. The key to developing and improving membrane separation processes lies in designing and fabricating customized porous membranes with specific physical parameters, including pore diameter, porosity, pore size distribution, pore length (membrane thickness), pore geometry, and pore connectivity. Polymeric porous membranes with vertically‐penetrative‐pores (PPMVs) represent a distinct category among the available membranes due to their unique characteristics such as short transport path, small trans‐membrane resistance, and simple pore geometry, as compared to other porous membranes with sponge‐like channels. In practical applications, PPMVs offer several advantages, including achieving higher flux rates, facilitating easier unidirectional transport, and enabling harmless biological extraction. Moreover, PPMVs can serve as ideal model systems for theoretical investigations on the fundamental mechanisms of separation and transport in academic research. With substantial advancements in fabrication technologies and application fields of PPMVs in recent years, it warrants a comprehensive perspective. In this mini‐review, we provide an overview of widely used fabrication methods for PPMVs, discuss their primary applications, and address the existing challenges and opportunities.

Strategies to Mitigate Biofouling of Nanocomposite Polymer-Based Membranes in Contact with Blood.

An extracorporeal blood purification method called continuous renal replacement therapy uses a porous hollow-fiber polymeric membrane that is exposed to prolonged contact with blood. In that condition, like with any other submerged filtration membrane, the hemofilter loses its properties over time and use resulting in a rapid decline in flux. The most significant reason for this loss is the formation of a biofilm. Protein, blood cells and bacterial cells attach to the membrane surface in complex and fluctuating processes. Anticoagulation allows for longer patency of vascular access and a longer lifespan of the membrane. Other preventive measures include the modification of the membrane itself. In this article, we focused on the role of nanoadditives in the mitigation of biofouling. Nanoparticles such as graphene, carbon nanotubes, and silica effectively change surface properties towards more hydrophilic, affect pore size and distribution, decrease protein adsorption and damage bacteria cells. As a result, membranes modified with nanoparticles show better flow parameters, longer lifespan and increased hemocompatibility.

SiO2 nanofiber reinforced P(VdF-HFP) based microporous polymer electrolytes for advanced energy storage applications

The application of ceramic nanofiller-dispersed microporous polymer gel electrolytes (MPGEs) in energy storage devices has been a subject of utmost research importance for a long time. However, a clear understanding of ion transport properties in this type of electrolyte is not yet achieved. The present article includes a detailed investigation of the uptake kinetics and ion transport mechanism in poly(vinylidene fluoride-co-hexafluoropropylene) [P(VdF-HFP)] based MPGEs reinforced with silica (SiO2) nanofibers. Very high ionic conductivity of 9.21 × 10−3 Scm−1 at ambient temperature has been achieved at a relatively low uptake ratio of 212 %, maintaining the dimensional integrity of the films when nanofiber content in P(VdF-HFP) is 2.5 wt%. This result ascertains the role of nanofibers in promoting ion transport in MPGEs, as revealed by XRD, FTIR, XPS, and simulative computational studies. The diffusive behavior of the MPGEs has been analyzed for both the liquid and the gel phases of the porous polymer membranes. The maximum diffusion coefficients for gel and liquid phases are 2.83 × 10−6 cm2s−1 and 2.36 × 10−12 cm2s−1, respectively, when the weight ratio of nanofiber is 2.5 %, confirming that the gel phase is the dominant conducting phase in MPGEs. The nanofiber-reinforced MPGEs show the highest electrochemical potential window of 4.6 V and excellent interfacial stability at 2.5 wt% of nanofiber concentrations. Nanofiber loaded MPGE also exhibits extreme non-flammability, which can be exposed to the flame for longer without burning. Being highly conductive with outstanding electrochemical, interfacial and flame retardant properties, the synthesized MPGEs could be a suitable candidate for next-generation energy-storing devices.

Stability of Porous Polymeric Membranes in Amine Solvents for Membrane Contactor Applications.

Membrane gas-liquid contactors have great potential to meet the challenges of amine CO2 capture. In this case, the most effective approach is the use of composite membranes. However, to obtain these, it is necessary to take into account the chemical and morphological resistance of membrane supports to long-term exposure to amine absorbents and their oxidative degradation products. In this work, we studied the chemical and morphological stability of a number of commercial porous polymeric membranes exposed to various types of alkanolamines with the addition of heat-stable salt anions as a model of real industrial CO2 amine solvents. The results of the physicochemical analysis of the chemical and morphological stability of porous polymer membranes after exposure to alkanolamines, their oxidative degradation products, and oxygen scavengers were presented. According to the results of studies by FTIR spectroscopy and AFM, a significant destruction of porous membranes based on polypropylene (PP), polyvinylidenefluoride (PVDF), polyethersulfone (PES) and polyamide (nylon, PA) was revealed. At the same time, the polytetrafluoroethylene (PTFE) membranes had relatively high stability. On the basis of these results, composite membranes with porous supports that are stable in amine solvents can be successfully obtained to create liquid-liquid and gas-liquid membrane contactors for membrane deoxygenation.

Cultivation and Transplantation of Three-Dimensional Skins with Laser-Processed Biodegradable Membranes.

For the treatment of irreversible, extensive skin damage, artificial skins or cultured skins are useful when allogeneic skins are unavailable. However, most of them lack vasculature, causing delayed perfusion and hence delay or failure in engraftment of the tissues. We previously developed a prevascularized three-dimensional (3D) cultured skin based on the layer-by-layer cell coating technique (LbL-3D skin), in which cells are seeded and laminated on a porous polymer membrane for medium supply to the thick cultured tissue. Recent animal studies have demonstrated that LbL-3D skin can achieve rapid perfusion and high graft survival after transplantation. However, there were practical issues with separating LbL-3D skins from the membranes before transplantation and the handling separated LbL-3D skins for transplantation. To address these problems, in this study, we examined the use of biodegradable porous polymer membranes that enabled the transplantation of LbL-3D skins together with the membranes, which could be decomposed after transplantation. Thin films made from poly (lactic-co-glycolic acid) (PLGA) were irradiated with femtosecond laser pulses to create micro through-holes, producing porous membranes. We designed and fabricated culture inserts with the PLGA membranes and cultivated LbL-3D skins with 2 × 106 neonatal normal human dermal fibroblasts and 1 × 104 human umbilical vein endothelial cells in the dermis of 20 cell layers and 1 × 105 neonatal human epidermal keratinocytes in the epidermis. Histological analyses revealed that the skins cultured on the PLGA membranes had thickness of about 400 μm and that there were no defects in the quality of the skins cultured on the PLGA membranes when compared with those cultured on the conventional (nonbiodegradable) commercial membranes. The cultured LbL-3D skins were then transplanted together with the PLGA membranes onto full-thickness excisional wounds in mice. At 7 days posttransplantation onto a mouse, the tissues above and below the membrane were connected through the holes with collagen-positive fibers that appeared to migrate from both the host and donor sides, and favorable reepithelization was observed throughout the transplanted skin region. However, insufficient engraftment was observed in some cases. Thus, further optimization of the membrane conditions would be needed to improve the transplantation outcome.

Establishing structure–property linkages for wicking time predictions in porous polymeric membranes using a data-driven approach

The goal of this study is to develop correlations between microstructure morphology and macroscopic material behavior, known as structure–property linkages. These correlations can be used to predict material behavior and enable virtual materials design efforts. In this work the structure–property linkages for the capillary-driven fluid transport through highly porous open-pored polymeric membranes are determined by a data-driven approach. To establish linkages, about 400 porous microstructures with different geometrical features are algorithmically generated and characterized in 3D, using fluid flow simulations and image analysis methods. The data processing pipeline for the generation and analysis of the microstructures is implemented by a generic workflow tool called KadiStudio, which is embedded in the research data infrastructure Kadi4mat. The data-driven analysis enables predictions about the propagation time of a fluid over definable distances when only the porosity and the ligament radius are known as microstructural properties. The generated knowledge can be utilized for an accelerated development of novel polymeric membranes with an optimized pore structure.

Lignin particles as green pore-forming agents for the fabrication of microporous polysulfone membranes

Templating polymeric membranes with micro-nano-scaled solid materials is an effective method to simultaneously improve the water flux and retention ratio. However, the fabrication of a green, recyclable, and size-controlled template material remains a challenge. Here, a new green pore-forming agent, lignin particles (LP), was developed to prepare porous polysulfone (PSF) membranes via the phase inversion technique. A series of LP have uniform sizes from ~200 nm to ~1800 nm. The performances of the templated PSF membranes cast at different sizes and contents of LP were examined for their surface and crosssection morphologies. The LP-templated PSF membranes displayed a remarkable enhancement in flux, porosity, and moisture content. Particularly, the PSF membranes cast with LP from ~200 to 1800 nm broke the traditional trade-off to a certain degree, which possessed stable retentions of bovine serum albumin (> 85 %) and significantly improved water flux (174.275 to 254.775 L m−2 h−1). In addition, the LP pore-forming agent is low-cost and environmentally friendly as it was prepared from industrial by-products and can be easily recycled. Overall, this study shows that lignin particles are green pore-forming agents that can be used for the fabrication of porous polymeric membranes with improved performance for water treatment.

A facile strategy to fabricate skin‐free porous polymer membranes based on sandwich structure

AbstractThe skin layer, i.e. the surface dense layer with relatively lower porosity, may significantly impede the permeability of porous polymer membranes. In this work, with the combination of experiment and finite element simulation, a facile strategy based on sandwich structure is proposed to eliminate the skin layer. The simulation results indicate that removing skin layers can increase the water flux of porous membranes by more than 4 times. In experiment, first the formation mechanism of skin layer is studied for the porous membranes fabricated from poly(ether‐ether‐ketone)/poly(ether‐imide) (PEEK/PEI) blend based on crystallization template. It is found that the stronger interaction between PEI and the polyimide releasing film during hot‐pressing is the cause of the PEEK skin layers of the obtained membranes. According to this mechanism, a skin‐free PEEK membrane is prepared from the PEI/(PEEK/PEI blend)/PEI sandwich structure. The separation test indicates that the PEEK membrane fabricated following the new strategy has remained rejection ratio and enhanced flux by 3–5 times as the simulation result predicts. Furthermore, the universality of developed sandwich strategy has been validated in polyformaldehyde/poly(L‐lactic acid) (POM/PLLA) blend (crystalline/crystalline system). Our results provide a novel solution to regulate the skin layer of porous membranes.

Designing a robust biocompatible porous polymeric membrane using Laponite and graphene oxide for versatile and selective adsorption of water contaminants

For reclaiming contaminated water, nanoparticle-incorporated porous polymeric membranes provide the requisite functionality for efficient and selective adsorption of toxic molecules. To this end, a simple yet innovative material selection strategy was adopted to prepare a robust and high-performance membrane system by the phase-inversion method using thermoplastic polyurethane (TPU), Laponite, graphene oxide (GO) and a hybrid derived from their aqueous “co-dispersion”, viz., Laponite/GO (LGO). The addition of 12 wt% LGO substantially improved the hydrophilicity, porosity, pure water flux (PWF), and mechanical properties of TPU membranes. Notably, the above membrane showed a striking 20-fold increase in PWF (from ∼27 to ∼652 Lm-2h−1), a 43-fold increase in elastic modulus, a 10-fold increase in tensile strength and a 3-fold increase in toughness and displayed synergistic improvement in mechanical properties. At 12 wt% LGO, the rejection efficiency of > 98%, >95%, and ∼86%, and the adsorption capacity of ∼47 mg/g, ∼49.3 mg/g and ∼16.8 mg/g for methylene blue (MB), crystal violet (CV) and rhodamine B (RhB) dyes, respectively were observed. The dye adsorption efficiency was comparable with that of poly(vinylidene fluoride) (PVDF)-LGO membranes. Owing to the anionic functional groups in LGO, the nanocomposite membranes displayed excellent selectivity of adsorption. The dye adsorption by the nanofiller-TPU membranes showed a pseudo-2nd-order kinetic behavior, indicating chemisorption; while the pristine TPU showed marginal physisorption of dyes. The LGO-filled membranes also showed efficient adsorption of Pb2+ and As5+ ions from water, with efficiency increasing with LGO content, showing > 90% efficiency with 15 wt% LGO. The nanocomposite membranes showed no cytotoxicity effect and supported the proliferation of human epidermal keratinocytes (HaCaT) cells. On these accounts, the LGO-TPU membranes promise the development of high-performance and cost-effective filtration membranes.

Porous honeycomb film membranes enhance endothelial barrier integrity in human vascular wall bilayer model compared to standard track-etched membranes.

In vitro vascular wall bilayer models for drug testing and disease modeling must emulate the physical and biological properties of healthy vascular tissue and its endothelial barrier function. Both endothelial cell (EC)-vascular smooth muscle cell (SMC) interaction across the internal elastic lamina (IEL) and blood vessel stiffness impact endothelial barrier integrity. Polymeric porous track-etched membranes (TEM) typically represent the IEL in laboratory vascular bilayer models. However, TEM stiffness exceeds that of diseased blood vessels, and the membrane pore architecture limits EC-SMC interaction. The mechanical properties of compliant honeycomb film (HCF) membranes better simulate the Young's modulus of healthy blood vessels, and HCFs are thinner (4 vs. 10 μm) and more porous (57 vs. 6.5%) than TEMs. We compared endothelial barrier integrity in vascular wall bilayer models with human ECs and SMCs statically cultured on opposite sides of HCFs and TEMs (5 μm pores) for up to 12 days. Highly segregated localization of tight junction (ZO-1) and adherens junction (VE-cadherin) proteins and quiescent F-actin cytoskeletons demonstrated superior and earlier maturation of interendothelial junctions. Quantifying barrier integrity based on transendothelial electrical resistance (TEER), membranes showed only minor but significant TEER differences despite enhanced junctional protein localization on HCF. Elongated ECs on HCF likely experienced greater paracellular diffusion than blocky ECs on TEM. Also, larger populations of plaques of connexin 43 subunit-containing gap junctions suggested enhanced EC-SMC communication across the more porous, thinner HCF. Compared with standard TEMs, engineered vascular wall bilayers cultured on HCFs better replicate physiologic endothelial barrier integrity.

Preserved subsurface morphology in NIPS and VIPS laser-induced graphene membranes affects electrically-dependent microbial decontamination

Laser-induced graphene (LIG) is a graphitic material that can be easily formed by CO2-laser irradiation on a variety of carbon-based substrates, including porous polymeric membranes. LIG-membrane formation involves lasing the top surface of a polymeric membrane, and converts essential polymer separation structures to porous LIG foam. However, in previous studies, separation properties could be partly recovered by forming LIG polymer composite layers or by coating the polymeric membrane substrate with trimethylaluminum (TMA) or graphene oxide (GO) to avoid melting or damaging the membrane pore structure and the subsurface polymeric structures during the lasing process. Herein, by optimizing the laser settings and fabrication conditions, we made LIG directly on uncoated porous PES membranes, while preserving the subsurface polymer. The effects of lasing on membrane properties were studied by comparing porous polymeric PES membranes fabricated using the non-solvent induced phase separation (NIPS) or the vapor-induced phase separation (VIPS) method. Membrane fabrication conditions such as the polymer concentration of the casting solution and the exposure time to the non-solvent were varied, and the NIPS method resulted in membranes with a finger-like polymer substructure morphology while the VIPS method resulted in membranes with an asymmetric cellular morphology. LIG-membranes prepared on NIPS membranes resulted in large permeability changes, while LIG on VIPS membranes gave only very minor changes. The antimicrobial activity of these LIG-membranes as porous electrodes was dependent on applied voltage and solution contact time and 4–6 log removal of bacteria at 10 V was achieved. Understanding LIG formation on porous polymeric membranes will minimize processing steps and might lead to electrically conductive membranes with controlled separation properties.

Application of Surface-Modified Nanoclay in a Hybrid Adsorption-Ultrafiltration Process for Enhanced Nitrite Ions Removal: Chemometric Approach vs. Machine Learning

Herein, we report the results of a study on combining adsorption and ultrafiltration in a single-stage process to remove nitrite ions from contaminated water. As adsorbent, a surface-modified nanoclay was employed (i.e., Nanomer® I.28E, containing 25-30 wt. % trimethyl stearyl ammonium). Ultrafiltration experiments were conducted using porous polymeric membranes (Ultracel® 10 kDa). The hybrid process of adsorption-ultrafiltration was modeled and optimized using three computational tools: (1) response surface methodology (RSM), (2) artificial neural network (ANN), and (3) support vector machine (SVM). The optimal conditions provided by machine learning (SVM) were found to be the best, revealing a rejection efficiency of 86.3% and an initial flux of permeate of 185 LMH for a moderate dose of the nanoclay (0.674% w/v). Likewise, a new and more retentive membrane (based on PVDF-HFP copolymer and halloysite (HS) inorganic nanotubes) was produced by the phase-inversion method, characterized by SEM, EDX, AFM, and FTIR techniques, and then tested under optimal conditions. This new composite membrane (PVDF-HFP/HS) with a thickness of 112 μm and a porosity of 75.32% unveiled an enhanced rejection efficiency (95.0%) and a lower initial flux of permeate (28 LMH). Moreover, molecular docking simulations disclosed the intermolecular interactions between nitrite ions and the functional moiety of the organonanoclay.

State-of-the-art review of porous polymer membrane formation characterization—How numerical and experimental approaches dovetail to drive innovation

Porous polymer membranes substantially contribute to an acceleration of sustainability transformation based on the energy efficient separation of liquid and gaseous mixtures. This rapid shift toward sustainable industrial processes leads to an increased demand for specifically tailored membranes. In order to predict membrane performance factors like permeability, selectivity and durability, the membrane formation process by film casting and phase inversion needs to be understood further. In recent years, computational models of the membrane formation process have been studied intensely. Their high spatial and temporal resolution allows a detailed quantitative description of phase inversion phenomena. New experimental techniques complement this development, as they provide quantitative data, e.g., on compositional changes of the polymer solution during membrane formation as well as the kinetic progression of the phase separation process. This state-of-the-art review compiles computational and experimental approaches that characterize the phase inversion process. We discuss how this methodological pluralism is necessary for improving the tailoring of membrane parameters, but that it is unlikely to be the way to the ultimate goal of a complete description of the evolution of the membrane structure from the initial demixing to the final solidification. Alternatively, we formulate an approach that includes a database of standardized and harmonized membrane performance data based on previously publicized data, as well as the application of artificial neural networks as a new powerful tool to link membrane production parameters to membrane performance.

Effect of Low Concentrations of Lithium Chloride Additive on Cellulose-Rich Ultrafiltration Membrane Performance

Various water treatment processes make extensive use of porous polymeric membranes. A key objective in membrane fabrication is to improve membrane selectivity without sacrificing other properties such as permeability. Herein, LiCl (0-2 wt.%) was utilised as a preforming agent in fabricating biomass-derived cellulosic membranes. The fabricated membranes were characterised by dope solution viscosity, surface and cross-sectional morphology, pure water flux, relative molecular mass cut-off (MWCO, 35 kDa), membrane chemistry, and hydrophilicity. The results demonstrated that at the optimum LiCl concentration (0.4 wt.%), there is an interplay of thermodynamic instability and kinetic effects during membrane formation, wherein the membrane morphology and hydrophilicity can be preferably altered and thus lead to the formation of the membrane with better rejection at no detriment to its permeability.

Porous rigid-flexible polymer membrane interface towards high-rate and stable zinc-ion battery

Although aqueous zinc-ion batteries have been widely investigated as promising energy storage devices, the side effect of irreversible dendritic growth on cycling stability still exists to impede their practical applications. In this work, the porous rigid-flexible polymer composite membrane is successfully constructed by coupling rigid polymers of intrinsic microporosity (PIMs) with highly flexible polyvinylidene fluoride (PVDF). The afforded PVDF-PIM (P-PIM) membranes present various morphologies according to the different rigidity of PIMs. As a protective layer of zinc (Zn) anode, the PVDF-PIM-1 (P-PIM-1) membrane with a unique “sea-islands” morphology exhibits excellent electrochemical performances. The rigid island-region consists mainly of porous PIM-1, which is enriched with Zn2+ transport channels to enable fast reaction kinetics, and the flexible sea-region has a good dynamic adaptive capability. After coating P-PIM-1 membrane on Zn anode, the symmetric battery could retain 99.6% Coulombic efficiency (CE) after 500 plating/stripping cycles at a current density of 4 mA cm−2. The assembling P-PIM-1@Zn//NH4V4O10 full battery delivers an ultra-long life of 14500 cycles and exceptional capacity retention of 113 mAh g−1 at 10 A g−1. The porous rigid-flexible interface provides a new approach for stable Zn anode.

Biodegradable poly-ε-caprolactone based porous polymer electrolytes for high performance supercapacitors with carbon electrodes

Herein, we report porous polymers electrolytes (PPEs), composed of a biodegradable polymer poly-ε-caprolactone (PCL), activated with organic liquid electrolyte (ethylene carbonate (EC)/propylene carbonate (PC)/NaClO4) and an ionic liquid (IL)-incorporated electrolyte (1-ethyl-3-methylimidazolium trifluoromethane-sulfonate (EMITf)/Na-trifluoromethane sulfonate (NaTf). The porous polymeric membranes are prepared via a simple, one step immersion precipitation method, which provide channels for ionic transport. Morphological/structural, thermal and electrochemical studies on PPEs exhibit excellent flexibility, good porosity (∼80%), high (∼90%) liquid electrolyte uptake and high room temperature ionic conductivity (1.8–1.9 × 10−3 Scm−1) with wide electrochemical stability window (>5.0 V). Quasi-solid-state carbon supercapacitors/electrical double layer capacitors (EDLCs) are fabricated from symmetrical activated carbon (AC) electrodes (derived from a waste-biomass, sugarcane bagasse), separated by PPE-films. The supercapacitor based on IL-incorporated PPE exhibits higher specific capacitance (∼170 F g−1) and specific energy (∼34 Wh kg−1) compared to the device based on organic solvents-based PPEs (∼130 F g−1 and ∼24 Wh kg−1, respectively). Substantial energy storage in supercapacitor is evident from the glow of LED (35–50 mW) for longer duration. The device demonstrates stable performance up to ∼10,000 charge-discharge cycles with ∼15% initial capacitance fading and ∼100% Coulombic efficiency.

Effect of Zr-Nanofiller on Structural and Thermal Properties of PVDF-co-HFP Porous Polymer Electrolyte Membranes Doped with Mg2+ Ions

New poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-co-HFP)/ZrO2-based nanocomposite porous polymer membranes were prepared with doping of magnesium ions using THF as solvent. These membranes were prepared using the solvent casting technique. The optimal nanofiller (0, 2, 4, 6, 8 and 10% Zr nanopowder) was incorporated into the PVDF-co-HFP/MgTf3/ZrO2 and the incorporation of the nanofiller results in an increase in the porosity of the prepared membranes. The structural, morphological and thermal properties of the nanocomposite porous polymer membranes were also investigated. The structural investigation and the identification of functional groups were accomplished using FTIR technique. X-ray diffraction (XRD) analysis was performed to ascertain the phase of polymer membranes and the phase change that happens upon interaction with nanofiller and Mg2+ ions. Assessment of the nanocomposite porous polymer membrane's morphology and porous structure was performed using a scanning electron microscope (SEM). DSC analysis was used to evaluate the thermal behaviour of the nanocomposite porous membranes. The electrical and dielectric studies confirmed the structural reformation of the polymer electrolyte materials. It was found that 8% nanofiller is the best conducting composition for maximum ionic conductivity, dielectric constant and Mg2+ ion mobility. The incorporation of ZrO2 nanofiller predominantly increases the number of free ions and mobility of the charge carriers in the composite polymer electrolyte systems.

High Pressures Gas Adsorption in Porous Media and Polymeric Membrane Materials

High Pressures Gas Adsorption in Porous Media and Polymeric Membrane Materials

Self-Adhesive Ionomers for Durable Alkaline Water Electrolysis

Low-temperature water electrolysis using anion conductive polymer electrolytes has several potential advantages over acid-based polymer electrolyzers. However, the formation of durable, high surface area electrodes remains a challenge. In particular, the adhesion and connectivity of high surface area, particulate catalysts to the porous transport layer is critically important to the long-term cell lifetime.In this study, a family of covalently bonded, self-adherent, hydroxide conducting ionomers has been synthesized and tested under alkaline electrolysis conditions. The ionomers are based on hydroxide conducting poly(norbornene) polymers used in fuel cell and electrolyzers. Ionomers used in electrolysis electrodes, especially at the oxygen gas producing anode, must provide adhesion between the catalyst particles, porous transport layer and solid polymer membrane. Simple mixtures of ionomer and catalyst can suffer from poor catalyst adhesion because only physical adhesion is used to bind the components together.The terpolymer and tetrapolymer ionomers used in this work have been functionalized to provide cites for chemical bonding of bis(phenyl)-A-diglycidyl ether to the ionomer, catalyst, and porous transport layer. The resulting electrodes show excellent adhesion of the catalyst particles to the porous transport layer, as determined by adhesion measurements. Electrolyzer results show stable voltage performance over long periods of time.