Arylene Ether Research Articles

Blend membranes of sulphonated poly(arylene ether sulphone) and sulphonated polybenzimidazole and their characterization for desalination applications

Blend membranes of sulphonated poly(arylene ether sulphone) and sulphonated polybenzimidazole and their characterization for desalination applications

Characterization of the thermomechanical and aging behaviour of PAEK and CF/PAEK composites under long-term high-temperatures

The growing use of poly(aryl ether ketone) (PAEK) polymers reinforced with carbon fiber (CF) aims to meet the increasing demand for thermoplastic composites in applications that require excellent mechanical properties and thermal stability at higher temperatures. This study investigated the physicochemical properties of PAEK and CF/PAEK composites under long-term high-temperature exposure (150 °C, 200 °C and 250 °C) for durations of 15, 30, and 45 days, aiming to elucidate the durability mechanisms and enhance understanding of their performance. Specifically, the changes in the flexural properties and dynamic thermo-mechanical properties of the materials were evaluated after long-term high-temperature treatment. The results indicated that both PAEK and CF/PAEK composites possess substantial potential for long-term high-temperature applications, with CF not significantly altering the fundamental high-temperature response of the PAEK matrix. Regarding durability mechanisms, at 150 °C, PAEK's amorphous region undergoes chain reorientation, while temperatures of 200 °C and 250 °C induce significant secondary crystallization, which significantly improved the high-temperature mechanical properties of these materials. Additionally, at temperatures up to 250 °C, shorter linear chain fragments form through oxidative scission in PAEK's amorphous molecular chains. This work not only enriches the existing data on the properties of PAEK and CF/PAEK composites after long-term high-temperature treatment, but also provides further insights into their durability mechanisms.

Direct oxygen insertion into C-C bond of styrenes with air.

Skeletal editing of single-atom insertion to basic chemicals has been demonstrated as an efficient strategy for the discovery of structurally diversified compounds. Previous endeavors in skeletal editing have successfully facilitated the insertion of boron, nitrogen, and carbon atoms. Given the prevalence of oxygen atoms in biologically active molecules, the direct oxygenation of C-C bonds through single-oxygen-atom insertion like Baeyer-Villiger reaction is of particular significance. Herein, we present an approach for the skeletal modification of styrenes using O2 via oxygen insertion, resulting in the formation of aryl ether frameworks under mild reaction conditions. The broad functional-group tolerance and the excellent chemo- and regioselectivity are demonstrated in this protocol. A preliminary mechanistic study indicates the potential involvement of 1,2-aryl radical migration in this reaction.

High-performance proton exchange membrane derived from N-heterocycle poly(aryl ether sulfone)s with ether-free hydrophilic blocks and exhibiting good stability and proton-conducting performance

The trade-off issue between proton conduction properties and stability is a constraint on the commercial application of non-fluorinated proton exchange membranes for fuel cells. To alleviate the issue, the multi-block N-heterocycle poly(aryl ether sulfone)s with ether-free hydrophilic blocks (b-SPDPESs), which is composited by diphenyl sulfone moieties and biphthalazindione structures with dense pendant benzenesulfonic groups, are developed to prepare high-performance membranes. The self-assembly effect of block copolymers not only improves the membrane stability but also constructs regular proton conduction channels. Moreover, the conduction channel consists of hydrophilic blocks without ether bonds, which effectively improves the tolerance of the membrane to radicals. The hydrogen-bond network between sulfonic groups and N-heterocycles in the channel improves the proton conduction efficiency, inhibits the swelling of the membrane, and improves the stability of the membrane. As a result, the swelling degree of b-SPDPESs membrane is only 15.8 %, the proton conductivity is as high as 238 mS cm−1, the membrane aging broken time at 80 °C is between 4 and 6.6 h, and the fuel cells loading the membranes and feeding with hydrogen and air perform the max power density of between 0.65 and 1.25 W cm−2. Modulating the sequence structure of chains and constructing multiblock polymers containing ether-free N-heretrocyclic blocks with sulfonic groups improve the stability of membranes while ensuring their proton conductivity.

Sulfonated poly(aryl ether) proton exchange membrane with excellent dimensional stability for hydrogen production by water electrolysis

The use of proton exchange membrane water electrolysis (PEMWE) for hydrogen production is considered a promising technology due to its high theoretical current density, gas purity, and energy efficiency. In this study, a fluorinated sulfonated hydrocarbon polymer was used to prepare hydrocarbon−based membranes for PEMWE that displayed exceptional stability. Notably, the SFPAE-60 membrane has a proton conductivity of up to 293.1 mS cm−2 at 80 °C and 100%RH, but its volumetric swelling ratio is only 47 %. Its dimensional stability is significantly better than that of previously reported sulfonated poly (aryl ether)−based proton exchange membranes (>100 %). The PEMWE based on the SFPAE-60 membrane achieves a current density of over 4800 mA cm−2 at 2.0V, confirming the membrane's applicability in actual water electrolysis. The results indicate that the electrolyte membrane of fluorinated sulfonated hydrocarbon polymer performs well in the PEM electrolyzer.

Electrochemical C-O and C-N Arylation using Alternating Polarity in Flow for Compound Libraries.

Etherification and amination of aryl halide scaffolds are commonly used reactions in parallel medicinal chemistry to rapidly scan structure-activity relationships with abundant building blocks. Electrochemical methods for aryl etherification and amination demonstrate broad functional group tolerance and extended nucleophile scope compared to traditional methods. Nevertheless, there is a need for robust and scale-transferable workflows for electrochemical compound library synthesis. Herein we describe a platform for automated electrochemical synthesis of C-X arylation (X = NH, OH) in flow to access compound libraries. A comprehensive Design of Experiment (DoE) study identifies an optimal protocol which generates high yields across > 30 aryl halide scaffolds, diverse amines (including electron-deficient sulfonamides, sulfoximines, amides, and anilines) and alcohols (including serine residues within peptides). Reaction sequences are automated on commercially available equipment to generate libraries of anilines and aryl ethers. The unprecedented application of potentiostatic alternating polarity in flow is essential to avoid accumulating electrode passivation. Moreover, it enables reactions to be performed in air, without supporting electrolyte and with high reproducibility over consecutive runs. Our method represents a powerful means to rapidly generate nucleophile independent C-X arylation compound libraries using flow electrochemistry.

Synthesis, characterization, computational studies and anti-inflammatory activity evaluation of some new indole substituted aryl ethers

A number of anti-inflammatory drugs with an aryl-ether part, such as Nimesulide and Rofecoxibs, have been shown to damage cells and kill liver cells. Keeping in view this rationale, the present work was aimed at synthesising new indole-substituted aryl ethers and evaluating their anti-inflammatory effects, which have minimal side effects. New indole substituted aryl ethers were synthesised. Spectral characterisation of these newly synthesised compounds was done using infrared (IR), proton nuclear magnetic resonance (1H NMR), and carbon-13 nuclear magnetic resonance (13C NMR) spectroscopy techniques. Further, In-silico studies were performed with an aim to evaluate the suitability of synthesised compounds as potential bioactive candidates for anti-inflammatory activity. The synthesised compounds were subjected to anti-inflammatory activity evaluation using the carrageenan-induced rat paw edema model. Primarily, the chemical reaction completion was ensured using TLC and M.P. Further, the structures of all synthesised compounds were confirmed by the results of spectra characterization. Results of in-silico study exhibited the docking of compounds on target proteins. On the basis of experimental findings, it was concluded that compound AG-1 (N-(1H-indol-3yl) methylene)-4-phenoxyaniline) is the most potent anti-inflammatory compound amongst all the newly synthesised compounds. Findings of the present study concluded that AG-1 could be used as a viable new lead bioactive compound to serve as a potent candidate for a new anti-inflammatory drug. The novelty of the present work resides in the simplest way of synthesis, a good docking score, and excellent anti-inflammatory potential when evaluated in vivo.

Electrochemical C‐O and C‐N Arylation using Alternating Polarity in Flow for Compound Libraries

Etherification and amination of aryl halide scaffolds are commonly used reactions in parallel medicinal chemistry to rapidly scan structure‐activity relationships with abundant building blocks. Electrochemical methods for aryl etherification and amination demonstrate broad functional group tolerance and extended nucleophile scope compared to traditional methods. Nevertheless, there is a need for robust and scale‐transferable workflows for electrochemical compound library synthesis. Herein we describe a platform for automated electrochemical synthesis of C‐X arylation (X = NH, OH) in flow to access compound libraries. A comprehensive Design of Experiment (DoE) study identifies an optimal protocol which generates high yields across > 30 aryl halide scaffolds, diverse amines (including electron‐deficient sulfonamides, sulfoximines, amides, and anilines) and alcohols (including serine residues within peptides). Reaction sequences are automated on commercially available equipment to generate libraries of anilines and aryl ethers. The unprecedented application of potentiostatic alternating polarity in flow is essential to avoid accumulating electrode passivation. Moreover, it enables reactions to be performed in air, without supporting electrolyte and with high reproducibility over consecutive runs. Our method represents a powerful means to rapidly generate nucleophile independent C‐X arylation compound libraries using flow electrochemistry.

Cross-Linking of Bromo-Pillar[5]arenes and Sulfonated Poly(Aryl Ether Ketone Sulfone) Enhances Proton Conductivity of Membranes at Low Ion Exchange Capacity

Cross-Linking of Bromo-Pillar[5]arenes and Sulfonated Poly(Aryl Ether Ketone Sulfone) Enhances Proton Conductivity of Membranes at Low Ion Exchange Capacity

Synthesis and performance of cross-linked poly(aryl ether nitrile) anion exchange membranes with dense cations and flexible side-chain structures for water electrolysis

Anion exchange membranes (AEMs) are the core components in anion exchange membrane water electrolysis (AEMWE), which play crucial role and affect the performance of AEMWE. In this work, a series of cross-linked poly(aryl ether nitrile) anion exchange membranes (CPAEN-dDQA-x) with dense cations and flexible side-chain structures are synthesized. By introducing multiple modification elements into the polymer structure simultaneously, the ion conductivity, dimensional stability, and alkali resistance stability of the prepared AEMs are effectively improved and balanced. The representative CPAEN-dDQA-0.25 showed water absorption of only 27.6 %, swelling rate of 11.2 %, and conductivity of 115.37 mS/cm at 80°C. The IEC and conductivity retention value of CPAEN-dDQA-0.25 after in 2 M NaOH solution at 80°C for 480 h were up to 86.2 % and 82 %, respectively. Meanwhile, the current density of the water electrolysis cell based on CPAEN-dDQA-0.25 is up to 477.0 mA/cm2 in 1 M KOH and 2.2 V, and its voltage don’t has significant change after 480 h of operation at a constant current density of 500 mA/cm2.

Synergistic Effects of Liquid Rubber and Thermoplastic Particles for Toughening Epoxy Resin

This study aims to investigate the toughening effects of rubber and thermoplastic particles on epoxy resin (EP), and to understand the mechanism underlying their synergistic effect. For this purpose, three EP systems were prepared using diglycidyl ether of bisphenol-A (DGEBA) epoxy resin (E-54) and 4,4-Diamino diphenyl methane (Ag-80) as matrix resin, 4,4-diaminodiphenyl sulfone (DDS) as a curing agent, and phenolphthalein poly (aryl ether ketone) particles (PEK-C) and carboxyl-terminated butyl liquid rubber (CTBN) as toughening agents. These systems are classified as an EP/PEK-C toughening system, EP/CTBN toughening system, and EP/PEK-C/CTBN synergistic toughening system. The curing behavior, thermal properties, mechanical properties, and phase structure of the synergistic-toughened EP systems were comprehensively investigated. The results showed that PEK-C did not react with EP, while CTBN reacted with EP to form a flexible block polymer. The impact toughness of EP toughened by PEK-C/CTBN was improved obviously without significantly increasing viscosity or decreasing thermal stability, flexural strength, and modulus, and the synergistic toughening effect was significantly higher than that of the single toughening system. The notable improvement in toughness is believed to be due to the synergistic energy dissipation effect of PEK-C/CTBN.

Catalytic, Enantioselective Cycloaddition of Pyrrole-2-methides with Aldehydes toward a Synthesis of 2,3-Dihydro-1H-pyrrolizin-3-ols.

An organocatalytic, highly enantioselective [6 + 2]-cycloaddition of 2-methide-2H-pyrroles with aryl acetaldehydes represents a novel and straightforward route toward densely substituted 2,3-dihydro-1H-pyrrolizin-3-ols, which were generated with good yields and high enantio- and diastereoselectivity. This one-step process involves a BINOL-phosphoric acid catalyzed reaction of 1H-pyrrole-2-carbinols with aryl acetaldehydes via the corresponding hydrogen-bonded, chiral 2-methide-2H-pyrroles.

Catalytic Cycloaddition Reactions of Ynol and Thioynol Ethers

Comprehensive SummaryElectron‐rich alkynes, such as ynol and thioynol ethers, have proven to be versatile and appealing partners in catalytic cycloaddition reactions, and thus have raised considerable attentions owing to the practical application in the modular assembly of valuable carbo‐ and heterocycles. The past decades have witnessed inspiring advances in this emerging field, and an increasing number of related discoveries have been exploited. Divided into two main sections on the basis of substrate type, in each section this comprehensive review will initially summarize their synthetic preparations and subsequently examine their reactivity in every sort of catalytic cycloaddition with emphasis on the methodology development, aimed at providing an access to this burgeoning area and encouraging further innovations in the near future. Key ScientistsFor the cycloaddition of ynol ethers, in 2004, Kozmin et al. firstly developed a silver‐catalyzed [2 + 2] cycloaddition of siloxy alkynes with electron‐poor olefins. In 2012, Hiyama et al. realized a palladium‐catalyzed formal [4 + 2] annulation of alkynyl aryl ethers with internal alkynes. In the same year, Sun et al. discovered an efficient [6 + 2] cyclization between siloxy alkynes and 2‐(oxetan‐3‐yl)benzaldehydes by applying HNTf2 as catalyst. In 2017, Wender et al. first utilized vinylcyclopropanes (VCPs) as coupling partners in the [5 + 2] annulation of ynol ethers. In 2018 and 2020, Ye et al. reported zinc‐catalyzed formal [3 + 2] and [4 + 3] cycloaddition, respectively. For the cycloaddition of thioynol ethers, in 2004, Hilt et al. realized a [4 + 2] cycloaddition by employing the alkynyl sulfides and acyclic 1,3‐dienes. In 2006, a ruthenium‐catalyzed [2 + 2] cycloaddition of thioynol ethers with bicyclic alkenes was accomplished by Tam. In 2014, Sun et al. reported an elegant iridium‐catalyzed click reaction of thioalkynes with azides.

Synthesis and Analysis of (γ,γ',γ''-Trifluoro)neopentyl (TFNP) Aryl Ethers as a Polar Fluoroaliphatic Motif.

A route is developed to (γ,γ',γ'''-trifluoro)neopentyl (TFNP) aryl ethers to extend the methods for the introduction of the tert-butyl group, carrying a fluorine on each of the methyl substituents. The route combines neopentyltosylate 3 with phenols and thiophenols to give efficient substitution reactions to the corresponding TFNP aryl ethers. The three C-F bonds adopt a helical propeller conformation as revealed by computation and single crystal X-ray structure analysis. The LogPs of TFNP ethers are lower (more hydrophilic) than their neopentyl analogues. The metabolism of selected TFNP ethers was explored in the fungus Cunninghamella elegans.

Hydrogenolysis of guaiacol and lignin to phenols over Ni/Nb2O5[sbnd]HZSM-5 catalyst

Selective hydrogenolysis of CAr-O bonds in lignin to produce aromatic compounds typically necessitates severe conditions. We developed a Ni/Nb2O5HZSM-5 catalyst that facilitates direct cleavage of guaiacol's aryl ether bonds at reduced temperatures (200 °C) and pressure (0.1 MPa H2), achieving a conversion of 89.5 % with the selectivity of phenol at 81.7 %, while retaining its activity after five cycles. The Ni/Nb2O5HZSM-5 exhibits a higher yield of phenol (49.1 mmolphenol·gNi−1·h−1), currently achieving the highest phenol yield among Ni-based catalysts. The addition of Nb2O5 enhances the dispersion of Ni and augments the effective surface area. In addition, the strong interaction of Nb with the HZSM-5 changed the electronic state of Nb and enhanced the resistance of the catalyst to high temperature and mechanical stress. Employing this catalyst for lignin depolymerization in an aqueous medium led to a 17.0 wt% yield of alkyl phenolic compounds. This approach represents an advancement in biomass resource conversion, circumventing the dependency on high-pressure and precious-metal catalysts, and signaling a new trajectory for sustainable biomass utilization in scientific research.

Photoinduced Birefringence and Liquid Crystal Orientation on Polymers with Different Azobenzene Content in the Main Chain.

In this paper, we give an overview of novel main-chain azobenzene-based fluorinated poly(arylene ether)s with different content of azo groups, aiming at providing a better understanding of the link between a number of N═N bonds and the macroscopic response of the material. We discuss chemical synthesis and molecular structure and report on a comprehensive analysis of the polymer properties, thermal behavior, and mechanical strength. We show that a higher content of azobenzene moieties reduces the mechanical strength of the polymer materials. On the other hand, polymers with a higher content of azobenzene demonstrate higher values of induced birefringence due to a larger number of azobenzene in the trans form. The photoisomerization constants of all polymers fall within a very close range. The minor variations are attributed to the number of azobenzene groups in the polymer composition and the conformational arrangements of the polymer chain packing. The developed light-sensitive polymers were employed for dynamic control and manipulation of the liquid crystal orientation by polarization of the incident light. After the double irradiation of the substrates using appropriate photomasks, we made patterned cells that consist of domains with different high-resolution liquid crystal director orientations.

Enhancing the interlaminar property of carbon fiber/poly(aryl ether ketone) composites with water‐soluble polyimide oligomer sizing agent

AbstractNovel water‐soluble polymer‐based sizing agents for carbon fiber/poly(aryl ether ketone) composites (CF/PAEK) have gained attention. However, a challenge remains: the sized CF bundles lack flexibility, and the effect of this on the properties of the composite has not been discussed. Herein, a water‐soluble polyimide oligomer (OL) sizing agent was developed, and the sizing effect was comprehensively evaluated. The conventional molecular weight polyimide (HP) sizing agent was also assessed for comparison. Although the interfacial shear strength of the sized CF monofilaments is enhanced due to improved surface roughness and wettability, the effect of the OL sizing agent on the composite's interlaminar shear strength (ILSS) and tow's flexibility differed from that of the HP sizing agent. Compared with HP‐CF, the yarn spreading rate of OL‐CF tow is increased by about eight times, and the ILSS of OL‐CF/PAEK composites with 2 and 5 MPa molding pressure is increased by 69% and 222%, respectively. The HP sizing agent weakens the tow's flexibility and yarn spreading ability, which is not conducive to the resin penetration in the tow, resulting in lower ILSS. In contrast, the OL sizing agent considers the tow's flexibility and composite's interlaminar property, showing great application potential.Highlights Two PI‐based sizing agents with diverse film‐forming capacities were prepared. The ILSS of CF/PAEK with OL sizing agent was significantly improved. HP sizing agent weakened the tow flexibility and interlaminar property. The interaction of sizing layer—resin penetration—ILSS was proposed.

Bifunctionalized MOFs modified poly (aryl ether ketone sulfone) ultrafiltration membranes with high-efficient BSA separation and dye adsorption

In this study, by connecting the amino ligand in ZIF-8-NH2 with an alkyl side chain containing sulfonic acid groups in a one-step method, a novel nanofiller (ZIF-8-NS) with bifunctional amino and sulfonic acid groups was formed. Sulfonated poly (aryl ether ketone sulfone) containing fluorene group (F-SPAEKS) was chosen as the polymer matrix. The nanofiller not only had good hydrophilicity but also had electrostatic interaction with the polymer matrix, which effectively promoted the compatibility problem among the polymer matrix and the filler. The nanofillers were characterized by XRD, FT-IR, SEM and XPS. The composite membranes were prepared by the NIPs method. The antifouling and separation properties of the prepared mixed matrix membranes (MMMs) were investigated using positively charged dye (RHB) and negative charge bovine serum albumin (BSA) as model contaminants. The water flux of the pure membrane achieved 529.16 L/m2 h. When the addition amount of ZIF-8-NS was 0.1 %, the water flux of M4 (F-SPAEKS/ZIF-8-NS-0.1 %) could reach 838.84 L/m2 h. The retention rate of the BSA solution could reach 99.06 %, and the FRR value was kept at a high level (81.45 %). Meanwhile, the dynamic retention of M4 on the primary adsorption of the dye RHB could even reach 99.89 %. Therefore, the innovative design of the novel MMMs not only improved the flux, retention, and other separation properties but also enhanced their excellent adsorption capacity for RHB dyes. This result indicated that the nanofiller ZIF-8-NS provided an interesting reference for the study of ultrafiltration membranes.

An effective strategy to enhance phosphoric acid retention and proton conductivity stability: Construction of proton transfer channels with starch rather than H3PO4

To enhance the phosphoric acid (PA) retention as well as maintain high proton conductivity of phosphoric acid doped proton exchange membranes at high temperature, we successfully design a series of phosphoric acid doped biobased composite membranes by incorporation of starch and graphene oxide (GO) into poly arylene ether ketones (PAEK). Proton transfer channels should be mainly built through dense hydrogen bonds formed from massive oxygen-containing groups of starch mainchain, which is confirmed by Molecular dynamics (MD) simulation, FT-IR and XRD analysis. The dense hydrogen-bond structure could construct fast proton transfer channels with extreme low doping level (0.00484 molH3PO4). The excellent PA retention properties with almost unchanged proton conductivity at high temperature (200 °C) for 600 min indicates that PA molecules are firmly fixed into membranes. Thus, in this study, we suggest a novel strategy for stablizing proton conductivity at high temperature and improving PA retention properties of PA doped membranes, which is building dense hydrogen-bond structure with low PA doping level.Based on the results in this study and the Grotthuss proton transfer mechanism, dense hydrogen-bonds from oxygen-containing groups in polymer backbones should be more stable than hydrogen-bonds from massive H3PO4 molecules with high acid doping levels to promote proton conduction.

The application of unsupervised machine learning for the elucidation of the burial effect of lignin in peatland: Case of TMAH thermochemolysis

Lignin is one of the major components of organic macromolecules in peatland. Analysis of lignin in sediments is considered as a valuable tool for understanding peat vegetation as well as carbon cycle. It provides valuable perspectives on different sides such as occurrence of various vegetation types and the extent of decay in terrestrial organic material. Thermochemolysis technique using tetramethyl ammonium hydroxide (TMAH) was used for lignin analysis, in an ombrotrophic peatland. It specifically breaks of O-aryl bonds followed by methylation of the lignin components yielding phenolic subunits. Several discrepancies exist between TMAH thermochemolysis findings and those obtained from previous investigations with CuO oxidation. This could be explained by the specific pool of aryl ether, specifically targeted by the thermochemolysis, with discarding of C-C bonds. Hence, this would show the capacity of TMAH thermochemolysis to cleave oxidised lignin leaving lignin of fresh and preserved organic matter intact. The TMAH thermochemolysis method's efficiency in molecular characterization and lignin degradation was evaluated using principal component analysis (PCA). PCA reduced dimensionality and redundancy of component contributions, with the first two principal components accounting for 70.33 % of the total variance. PCA has reinforced the selectively of the thermochemolytic approach in targeting O-aryl bonds while maintaining C-C bonding of polyphenolic sub-units. Hence, two distinct oxidation phases: recent (acrotelm and mesotelm) and older (catotelm) have been revealed. PCA was applied to diagenetic and source vegetation proxies, revealing strong agreement among variables which is supported by the use of molecular ratios as indicators of organic matter source and dynamics in a peat core.