Hybrid Anion Exchange Membranes Research Articles

Hybrid polymer inclusion membrane as anion exchange membrane for recovering Pd2+ ions in electrogenerative process

A novel non-plasticized nano-porous hybrid inorganic-organic polymer inclusion membrane (PIM) was synthesized, characterized, and evaluated as an anion exchange membrane for application in electrogenerative processes to recover Pd2+ ions. Ionic liquids 1-ethyl-3-me­thyl­imidazolium chloride (EMIM-Cl) and 1-butyl-3-methylimidazolium chloride (BMIM-Cl) were used as the carrier molecules in the polymeric network of PIM to enhance anion exchange process. This hybrid anion exchange membrane also consists of a polymeric matrix of non-plasticized cellulose triacetate modified by incorporating an inorganic material (silane) prepared by the sol-gel route. Different parameters affecting the ion transport performance efficiency, i.e., the composition of the membrane, type of ionic liquid (carrier molecule) and ion–exchange capacity, were investigated and optimized. In the electrogenerative process, the results revealed that the prepared PIM yields better recovery results for recovering Pd2+ ions from its chloride solution compared to the commercial anion exchange membrane Neosepta® AM-01, with a full recovery of 100 mg/L Pd2+ ions in 30 min. This preliminary study shows that the prepared low-cost hybrid anion exchange membrane PIM can act as an inexpensive material suitable for the rapid and efficient recovery of Pd2+ ions from an aqueous solution.

Construction of polysulfone anion exchange hybrid membranes by incorporating carbon quantum dots and facilitated transport mechanisms

Low ion conductivity and poor alkali resistance are still the two major obstacles for the applications of anion exchange membranes (AEMs). In this work, the combined strategies of Carbon quantum dots (CQDs) hybrid and cross-linking modification via side-chains designing were employed to prepare organic–inorganic hybrid AEMs. Then, the cross-linked quaternized polysulfone (CQPSf-CQDs) hybrid AEMs by incorporating carbon quantum dots were successfully fabricated. After hybrid and cross-linking, the mechanical properties of CQPSf-CQDs hybrid AEMs were higher than that of the pristine one, reaching 49.4 MPa for the best one. Meanwhile, the existence of CQDs can expand the hydrophilic area in the membrane, which is beneficial to the transport of OH-. The incorporated CQDs interact weakly with cationic groups in the side chains through hydrogen bonds. The simulation results further demonstrated that the introduction of CQDs was beneficial to the construction of hydrophilic and hydrophobic domains, thereby increasing OH- conductivity. In addition, the prepared hybrid membranes own excellent dimensional stabilities and ion transport performances. These preliminary results give us a lot of hopes for further experiments and optimizations for the hybrid AEMs.

Inorganic‐Organic Hybrid Anion Conducting Membranes Based on Ammonium‐Functionalized Polyethylene Pyrrole‐Polyethylene Ketone Copolymer

Back Cover: In article number 2100409 by Voto Di Novo and co-workers, the incorporation of tantalum oxide into trimethylammonium-functionalized polyethylene pyrrole-co-polyethylene ketone is carried out for the preparation of inorganic–organic hybrid anion exchange membranes, which are promising candidates for application in electrochemical energy conversion devices.

Preparation and characterization of organic-inorganic hybrid anion exchange membrane based on crown ether functionalized mesoporous SBA-NH2

In this paper, self-made diformyl-dibenzo-18-crown-6 ether (DDB 18 C 6 ) is in-situ grafted into the pores of mesoporous molecular sieve (SBA-NH 2 ), and then the aforementioned modified molecular sieve (SBA-C) is introduced into the polyvinyl alcohol solution, and then the glutaraldehyde as the crosslinking agent to synthesized the anion exchange membrane under for fuel cell application. During the experiment, a series of anion exchange membranes (P-(SBA x% -C), x is the mass fraction of SBA-NH 2 ) is developed and the pore channels and chemical structures of the aforementioned membrane is verified by FT-IR, SAXD, N 2 adsorption-desorption, 1 H NMR and XPS. Moreover, the performance of the membrane synthesized in this paper is also investigated and the results revealed that the unique membrane internal structure can improve the OH − transportation efficiency. Furthermore, the ionic conductivity of P-(SBA 10% -C) membrane is the highest (0.107S·cm −1 ) and the power density is the highest (354.8 mW cm −2 ) at 80 °C. By immersing P-(SBA 10% -C) membrane in 6 mol L −1 KOH solution for 168 h, the conductivity at 80 °C only decreased by 2%, proving that P-(SBA 10% -C) has a higher conductivity, good single cell performance and alkali stability. • A new kind of mesoporous molecular sieve with ordered pores grafted with crown ether was prepared. • A new type of anion exchange membrane with ordered mesoporous channels grafted with crown ether was prepared. • Using crown ether to complex K + to improve the conductivity of anion exchange membranes. • Prepared membrane showed excellent OH − conductivity and alkaline stability.

Inorganic‐Organic Hybrid Anion Conducting Membranes Based on Ammonium‐Functionalized Polyethylene Pyrrole‐Polyethylene Ketone Copolymer

AbstractNew inorganic‐organic hybrid anion exchange membranes are produced after incorporation of tantalum oxide into trimethylammonium‐functionalized polyethylene pyrrole‐co‐polyethylene ketone (functionalized polyketone, FPK), obtained by the chemical modification of a polyketone polymer. The influence of tantalum oxide fillers on the properties of the synthesized membranes is investigated. The interaction between inorganic fillers and the polymer chains is studied using Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR‐FTIR). The thermal analysis of the FPK membranes reveals they are thermally stable at up to 250°C. However, the incorporation of the inorganic fillers reduces the thermal stability. Modulated Differential Scanning Calorimetry (MDSC) results indicate that the inclusion of inorganic fillers leads to an increase in crystallinity. This study reports that the properties of the bulk polymer can be tuned by controlling the degree of functionalization and content of inorganic fillers, as confirmed by Near Ambient Pressure X‐Ray Photoelectron Spectroscopy (NAP‐XPS) studies. Finally, Broadband Electrical Spectroscopy (BES) studies demonstrate that the hybrid membranes are characterized by several polarization phenomena contributing to the overall ion conductivity of the material, which at RT is of 1.46 and 1.61 mS cm−1 for the FPK cast membrane and the hybrid membrane with 5.0 wt.% of Ta2O5 filler, respectively.

Highly hydroxide-conducting hybrid anion exchange membrane with functional COF-enhanced ion nanochannels

Anion exchange membranes with potentially high conductivity and stability are urgently demanded in alkaline anion exchange membrane fuel cells (AEMFCs). However, the design and preparation of novel hydroxide-conducting material remain grand challenges. Herein, we demonstrate a significantly enhanced hydroxide conduction hybrid membrane with multi-ion nanochannels assembled by embedding two-dimensional covalent organic framework (COF) sheets into one-dimensional comb-shaped poly (2,6-dimethyl-1,4-phenylene oxide) (PPO) chains. Hydrophilic imidazole-based ionic liquids (im-IL) in-situ polymerize within the ordered pores of COF PI-2, forming long-range continuous ion channels. Then the poly ionic liquid-loaded covalent organic frameworks (im@PI-2) as a novel filler is embedded into imPPO to construct hybrid membranes with multi-ion nanochannels. A remarkable hydroxide conductivity of 147 mS/cm (80 °C and 100% RH) and a maximum power density of 140 mW/cm2 are readily achieved for the hybrid membrane with 5 wt% im@PI-2 content. Particularly, the chemical stability, thermal stability, mechanical properties, and swelling resistance of the hybrid membrane are dramatically promoted by the introduction of im@PI-2. Meanwhile, the transfer of hydroxide in hybrid AEM is investigated by molecular dynamics simulations, which clarify the significant role of PI-2 one-dimensional channels in elevating hydroxide transport.

Hybrid anion exchange membranes with adjustable ion transport channels designed by compounding SEBS and homo‐polystyrene

AbstractHybrid anion exchange membranes (AEMs) were prepared via chemically functionalizing and crosslinking poly(styrene‐b‐[ethylene‐co‐butylene]‐b‐styrene) (SEBS) copolymers and low molecular weight homo‐polystyrene (hPS). Via sequential chloromethylation, crosslinking, quaternization, and alkalization, a series of hPS/SEBS AEMs were obtained with varying content of hPS. Systematic structural, morphological, mechanical, absorption, and transport measurements reveal that these properties depend on the total PS content in the membranes. Particularly, increasing total PS content causes (a) PS domains in the AEMs transition the cylindrical morphology to lamella‐like morphology with comparable correlation length; (b) Young's modulus, water uptake, swelling ratio, ionic exchange capacity and ionic conductivity of the AEMs, and Tg of PS phase increase. In addition, the alkaline stability of the hPS/SEBS AEMs is also improved by addition of hPS. These findings suggest that the proposed method can develop high performance SEBS AEMs that are suitable for fuel cell applications.

Highly hydroxide-conductive anion exchange membrane with PIL@MOF-assisted ion nanochannels

A highly hydroxide-conducting anion exchange membrane with well-organized multi ion channels were fabricated via incorporating poly ionic liquids modified MIL101 (PIL@MIL101) into imidazolated poly (2,6-dimethyl-1,4-phenylene oxide) (ImPPO). 1-Vinyl-3-ethylimidzolium bromine was first immobilized in MIL101 cages via supercritical fluid impregnation method. Afterwards, the rigid-assisted ion nanochannels were constructed by in-situ polymerization of ionic liquids within the long-range ordered pores of MIL101. Meanwhile, PPO was functionalized by 1-ethyl-2-methyimidzolium to prepare comb-shaped ImPPO with enhanced microphase separation structure. Then the PIL@MIL101 was combined with ImPPO to fabricate hybrid anion exchange membrane with well-organized multiple ion channels. The OH− conductivity of the hybrid membrane significantly reached 138mS/cm at 80°C (176% higher than that of pristine membrane). Furthermore, the stability and mechanical properties of the hybrid membranes were remarkably enhanced. The excellent performances render the hybrid membrane a good candidate for the application in anion exchange membrane fuel cells.

Preparation and characterization of a sol-gel derived silica/PVA-Py hybrid anion exchange membranes for alkaline fuel cell application

Ammonium functionalized anion exchange silica precursor (AESP) is synthesized by 3-(2-Aminoethylamino) propyltriethoxysilane and (2, 3-epoxypropyl) trimethylammonium chloride. Then the corresponding series of membranes based on pyridine functionalized polyvinyl alcohol (PVA-Py) with varying AESP content are prepared using sol-gel method. Obtained membranes show ion exchange capacities (IEC) ranging from 0.54 mmol·g−1 to 0.92 mmol·g−1, but the opposite trend of water uptakes (WU) from 123.97% down to 69.09% because of the formation of organic-inorganic network. The hybrid membranes also exhibit good thermal stability (>140 °C), excellent mechanical properties (25.37 MPa) and high OH− conductivity (9.63 × 10−2 S·cm−1, 80 °C). Compared with the commercial Nafion®-117 membrane, the prepared hybrid membrane performs a much lower methanol permeability (7.57 × 10−8 cm2·s−1 for prepared membrane, 2.00 × 10−6 cm2·s−1 for Nafion®-117 membrane, 3 M methanol solutions, 30 °C). Only 10.7% decreases in OH− conductivity can be observed in 6 M 80 °C NaOH solutions after 360 h immersions, exhibiting excellent alkaline stability. The highest peak power density of the single cell with 5 M KOH + 3 M methanol fuel is 52.56 mW·cm−2 at 80 °C and 0.2 MPa O2.

Novel Quaternary Ammonium-Functionalized Covalent Organic Frameworks/Poly(2,6-dimethyl-1,4-phenylene oxide) Hybrid Anion Exchange Membranes with Enhanced Ion Conductivity and Stability.

Here we report a new hybrid anion exchange membrane with enhanced hydroxide conductivity and excellent chemical and dimensional stability by incorporating quaternary ammonium (QA)-functionalized covalent organic framework into brominated poly(2,6-dimethyl-1,4-phenylene oxide) (BPPO). N,N,N',N' -Tetramethyl-1,6-hexanediamine (TMHDA) was impregnated into the pores of COF-LZU1 via a vacuum-assisted method, followed by reacting with allyl bromide. The generated QA groups were immobilized within the highly ordered pores of COF-LZU1 via in situ polymerization, forming long-range ordered multiple ion channels. The obtained QA@COF-LZU1 was then mixed with QAPPO to construct a hybrid anion exchange membrane for anion exchange membrane fuel cells (AEMFCs). The hydroxide conductivity of QA@COF-LZU1/PPO hybrid membrane increased up to 168.00 mS cm-1 at 80 °C, about 77% higher than that of pristine membrane. In addition, alkaline stability and thermal stability of the hybrid membranes were obviously enhanced. The excellent performance and the outstanding chemical stability render the COF hybrid membrane a good candidate for the application in AEMFCs.

3-Glycidoxy-propylthrimethoxysilane improved anion exchange membranes based on quaternized poly(2,6-dimethyl-1,4-phenyleneoxide)

The organic-inorganic hybrid anion exchange membranes were prepared from quaternary triethylamonium functionalized poly(2,6-dimethyl-1,4-phenyleneoxide) (QPPO) and 3-glycidoxypropylthrimethoxysilane (GOPS) with different ratios. The obtained membranes are termed as QPPOx-Gy, where x and y are the mole ratios of triethylamine and the siloxane GOPS to the bromomethyl groups of the polymer, respectively. The resultant hybrid membranes are thermally stable up to 200 °C and exhibit a tensile stress of around 10 MPa. The incorporated GOPS endows the hybrid membranes with increased water uptake and conductivity due to the more hydroxyl groups containing in the hydrolytic networks of GOPS in the membranes. A conductivity of 46.0 mS cm−1 is achieved by the QPPO0.4-G0.55 membrane in water at 80 °C, which is about 20 mS cm−1 higher than the conductivity of the pristine QPPO0.4 membrane. In addition, the QPPO0.4-Gy hybrid membranes possess enhanced alkaline tolerance toward the attack of hydroxide ions. After soaked in 1 M KOH at 60 °C for 480 h, the hybrid membranes retained more than 16–22% of the initial conductivity compared to the pristine QPPO0.4 membrane.

Electrochemical characterizations and reverse electrodialysis performance of hybrid anion exchange membranes for salinity gradient energy

Reverse electrodialysis (RED) is a technique that utilizes the salinity gradient through ion exchange membranes to generate electrical power. In order to make this technology feasible, innovation is required to improve a critical subcomponent, the ion exchange membrane, especially in the selection of appropriate membrane materials and the design of proper RED membranes. This study presents a novel and cost-competitive method for the design of anion exchange membranes (AEMs) by organic-organic hybridization. The low-cost and charge-possessing polymer, poly (diallyldimethylammonium chloride) and poly (vinyl alcohol) (abbreviated as PDDA and PVA, respectively) are blended in different mass ratios to form an AEM. The effect of various PDDA loadings on the electrochemical characterizations of the membranes was investigated. The key properties such as electrical resistance, permselectivity and ion exchange capacity were found to be improved with increasing the mass blend ratio of PDDA. Specifically, the increase of PDDA mass ratio significantly decreased the level of membrane resistance, which majorly contributed to the performance of RED power generation: reached the maximum power density of 0.58 W/m2. Such fabrication method of AEMs may provide the feasible design strategy of potential ion exchange membranes for a viable RED energy conversion.

In-situ preparation of cross-linked hybrid anion exchange membrane of quaternized poly (styrene-b-isobutylene-b-styrene) covalently bonded with graphene

Introducing graphene into polymer matrix is an effective way to enhance performances of anion exchange membrane (AEM). However, utilizing the advantages of graphene by physical approach is limited due to the weak interface interaction between graphene and polymer matrix. Herein, we report an effective strategy to covalently bond graphene with polymer matrix to improve the interface interaction and further to improve the properties of AEM. A series of cross-linked quaternized graphene-based hybrid AEM were fabricated by covalently bonding poly (vinylbenzyl chloride) grafted graphene (GN-g-PVBC) copolymer with chloromethyl functionalized poly (styrene-b-isobutylene-b-styrene) (SIBS) through the cross-linker (N,N,N′,N′-tetramethyl-1,6-hexanediamine) by in-situ synthetic approach. The interface interaction between graphene and QSIBS is greatly enhanced according to micromorphology characterization of the hybrid membrane. The cross-linked quaternized hybrid AEM containing 0.55 wt% of GN-g-PVBC exhibits obviously improved dynamical mechanical properties (storage modulus: 418 MPa), ion conductivity (1.81 × 102 S cm−1), methanol barrier property (5.19 × 10−7 cm2 s−1), selectivity (3.49 × 104 S s cm−3) at 60 °C and especially a comparably excellent chemical stability to that of Nafion 115 due to the enhanced interface interaction between graphene and the polymer matrix.

Novel imidazole‐grafted hybrid anion exchange membranes based on poly(2,6‐dimethyl‐1,4‐phenylene oxide) for fuel cell applications

ABSTRACTNovel organic–inorganic hybrid membranes, based on poly(2,6‐dimethyl‐1,4‐phenylene oxide), have been prepared through 1,2‐dimethylimidazole functional groups and double crosslinking agents including 3‐glycidyloxypropyltrimethoxysilane and tetraethyl orthosilicate by sol–gel process for the purpose of improving the conductivity and alkaline resistance. The structure of membranes was characterized using Fourier‐transform infrared spectra, 1H NMR, and X‐ray diffraction. The physico‐chemical properties of all membranes were shown in ion exchange capacity, water uptake, stability, and conductivity. Membranes with OH– conductivity up to 0.022 at 25 °C and 0.036 S cm−1 at 80 °C. Promisingly, the chemical stability of the resulting membranes remains unchanged after storage in 2 mol dm−3 KOH at 25 °C over at least 10 days. The tensile strength can be higher than 30 MPa, and the elongation at break (Eb) is in the range 6.68–10.84%. Hence, this hybrid membrane can be potentially applied in alkaline fuel cells. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46034.

Hybrid anion exchange membranes with self‐assembled ionic channels

AbstractA novel strategy for fabricating nanocomposite anion exchange membranes (AEM), which can construct self‐assembled ionic channels via in situ Menshutkin reaction, is proposed. The TEM image of a nanocomposite AEM based on chloromethylated polysulfone (CMPSF) and functionalized polyhedral oligomeric silsesquioxane (POSS) confirms the existence of core‐shell clusters. The ionic conductivity of these nanocomposite AEMs shows a notable increase when the content of functionalized POSS exceeds the percolation threshold. Furthermore, the optimized nanocomposite AEM has higher ionic conductivity than the control AEM with similar ion‐exchange capacity due to the well‐developed morphology.

Hybrid anion exchange membrane of hydroxyl-modified polysulfone incorporating guanidinium-functionalized graphene oxide

Incorporating nanofillers is an effective method to balance conductivity and mechanical strength of anion exchange membranes (AEMs). In this work, a series of AEMs were prepared via embedding guanidinium-functionalized graphene oxide (GGO) into un-quaternized, diethanolamine-modified polysulfone (HPSf). The improved hydrophilicity of HPSf allows for better compatibility between GGO and polymer and also gives higher water uptake, which is beneficial for facilitating ion transport and alleviating hydroxide attack. AEM of HPSf embedding an optimized amount of GGO (0.88 mmol g−1) exhibits the highest conductivity of 11 mS cm−1 at 30 °C, which is 38% higher than that of pristine PSf-GGO membrane. It also possesses excellent anti-swelling stability (9% swelling ratio at 60 °C). When treated with 1 M NaOH at 60 °C for 120 h, HPSf-GGO-25% experienced a conductivity decay by 25%. Our work provides a route to fabrication of hybrid AEMs with improved interface properties and well-balanced conductivity and robustness.

One‐Pot Synthesis of Chloromethylated Mesoporous Silica Nanoparticles as Multifunctional Fillers in Hybrid Anion Exchange Membranes

AbstractChloromethylated mesoporous silica nanoparticles (CM MSN) were synthesized through co‐condensation of tetraethoxysilane and (chloro) phenyltrimethoxysilane precursors using hexadecyl trimethyl ammonium bromide as template. With the addition of the particles into chloromethylated poly (ether ether ketone) (PEEK), the hybrid membranes were prepared by a solution‐casting method after complete quaternization of the casting solution. The successful synthesis of the particles was verified by transmission electron microscopy, X‐ray diffraction and Fourier transform infrared spectroscopy while the effect of CM MSN incorporation on membrane performance including thermal stability, mechanical strength and hydroxide conductivity was investigated by thermal gravimetric analysis, electronic stretching machine, alternating‐current impedance and so on. Owing to the large pore volume and high surface area of the particles, the hybrid membranes exhibited enhanced hydroxide conductivity (88.7% increase at 60 °C, 100% RH with 5.0 wt% filling content) due to an increase in ion concentration and optimization of the channel morphology. Besides, higher mechanical strength, thermal and dimensional stability of hybrid membranes were obtained compared with those of the imidazolium PEEK membrane.

Imidazolium-based organic–inorganic hybrid anion exchange membranes for fuel cell applications

Imidazolium-based ionic liquids and imidazolium-based organic–inorganic hybrid alkaline anion exchange membranes (AEMs) are synthesized and investigated in the present work. The imidazolium-based hybrid AEMs are prepared via in situ cross-linking of styrene, acrylonitrile, 1-vinyl-propyl-triethoxysilaneimidazolium chloride ([VPSIm][Cl]) and 1-vinyl-3-butylimidazolium bromide ([VBIm][Br]), followed by anion exchange with hydroxide ions. The water uptake and swelling degree of the hybrid AEMs decrease with increasing [VPSIm][Cl] content due to the formation of an Si–O–Si inorganic network in the membranes. The resulting organic–inorganic hybrid AEMs show good thermal stability, excellent mechanical properties and high conductivity (above 10−2Scm−1 at room temperature in liquid water). Compared with samples without the addition of [VPSIm][Cl], the hybrid membranes show much higher alkaline stability, and the hybrid AEMs displayed excellent chemical stability up to 480h in 2M KOH solution at 60°C.

A novel hybrid anion exchange membrane for high performance microbial fuel cells

A novel titanium dioxide (TiO2)–quaternized poly(vinyl alcohol) (QAPVA) hybrid anion exchange membrane (T membrane) is prepared, and its feasibility for use in microbial fuel cells (MFCs) is investigated in this study.

Hybrid anion-exchange membranes derived from quaternized polysulfone and functionalized titanium dioxide

Polysulfone is modified via chloromethylation and TiO2 is functionalized by three modification reagents (anionic surfactant, 1,3-propane sultone and Dopamine). Based them, a series of promising organic-inorganic hybrid membranes for anion-exchange membrane fuel cells have been prepared by incorporating functionalized TiO2 submicrospheres into the chloromethylated polysulfone, subsequent quaternization and alkalization. The chloromethylation process is confirmed by Nuclear magnetic resonancespectra. The functionalization of TiO2 is proved through Fourier transform infrared spectroscopy and Thermogravimetric analysis. The quaternization is testified by contact angle measurement. Associated characteristics of the hybrid membranes were investigated, including water uptake, swelling behavior, mechanical property and ion conductivity. Compared with other anion-exchange membranes, the hybrid membranes containing 5% TiO2 with –SO3H groups exhibits higher ionic conductivity because of the acid-base ionic interactions between the inorganic filler and polymer chains. It demonstrates an ionic conductivity of 3.13×10−2 S/cm and an acceptable alkaline solution stability at 60°C.