Porous Ionic Polymers Research Articles

Processable hypercrosslinked ionic networks for effective removal of methyl orange

Synthesis of adsorbents with permanent micro/mesoporous structures, tunable functional groups and processability is of great interest in industrial-scale processes for treating dye wastewater. Herein, a feasible crosslinking method has been employed to prepare porous ionic polymers (imidazolium and pyridinium-based) as adsorbents. The obtained materials have been utilized for the removal of methyl orange from aqueous solution and the maximum capacities of imidazolium-based adsorbents reached up to 1159 mg/g, which is superior to those of pyridinium-based ones and most known porous sorbents. The binding energies drawn from theoretical calculations based on density functional theory (DFT) proven the strong interactions between ionic units and dyes. Furthermore, freestanding porous membranes were fabricated from the adsorbents successfully by a step-by-step cross-linking process, implying their great potential in practical anionic dye removal.

Phosphonium-Based Porous Ionic Polymer with Hydroxyl Groups: A Bifunctional and Robust Catalyst for Cycloaddition of CO2 into Cyclic Carbonates.

The integration of synergic hydrogen bond donors and nucleophilic anions that facilitates the ring-opening of epoxide is an effective way to develop an active catalyst for the cycloaddition of CO2 with epoxides. In this work, a new heterogeneous catalyst for the cycloaddition of epoxides and CO2 into cyclic carbonates based on dual hydroxyls-functionalized polymeric phosphonium bromide (PQPBr-2OH) was presented. Physicochemical characterizations suggested that PQPBr-2OH possessed large surface area, hierarchical pore structure, functional hydroxyl groups, and high density of active sites. Consequently, it behaved as an efficient, recyclable, and metal-free catalyst for the additive and solvent free cycloaddition of epoxides with CO2. Comparing the activity of PQPBr-2OH with that of the reference catalysts based on mono and non-hydroxyl functionalized polymeric phosphonium bromides suggested that hydroxyl functionalities in PQPBr-2OH showed a critical promotion effect on its catalytic activity for CO2 conversion. Moreover, PQPBr-2OH proved to be quite robust and recyclable. It could be reused at least ten times with only a slight decrease of its initial activity.

Porosity-Induced Selective Sensing of Iodide in Aqueous Solution by a Fluorescent Imidazolium-Based Ionic Porous Framework.

Developing a chemosensor for rapid, sensitive, and visual detection of iodide (I-) by a simple synthetic strategy is still challenging. Herein, we report a highly efficient iodide sensor by simply introducing ionic imidazolium groups into the porous network. This sensor, that is, a fluorescent ionic porous framework (IPF), was prepared by the quaternization reaction of octa((benzylchloride)ethenyl)silsesquioxane and 1,4-bis(1H-imidazole-1-yl)benzene and exhibited moderate porosity with a Brunauer-Emmett-Teller surface area of 379 m2 g-1 and blue fluorescence when excited by UV light. The IPF suspension in water can detect I- with high sensitivity and selectivity among various anions and quick response by fluorescence quenching. In contrast to no response toward I- by the linear model compound and the enhanced sensing performance with an increment of porosity, this finding indicates that the porosity of IPF is important for the detection of I- and an inducement of the sensing process. A fluorescent paper sensor was further developed, which shows high efficiency for the visual detection of I- similar to the abovementioned sensor, suggesting its potential in convenient and on-site sensing of I-. In addition, the paper sensor is recyclable with a remarkable fluorescence resuming ratio of 83% after 10 times cycle detection. Moreover, the developed sensor is used for the analysis of real samples. This work represents the first example of the detection of I- by an ionic porous polymer. Compared with conventional iodide sensors, the present sensor does not require unique structures to form the pseudocavity during sensing I- and can easily achieve high efficiency by incorporating ionic hydrogen bond donors into the porous network, indicating the importance of porosity and the feasibility of replacing the pseudocavity with a real cavity (or pore). More iodide sensors with high efficiency can be designed and fabricated by this novel and simple strategy.

Pd nanoparticles stabilized with phosphine-functionalized porous ionic polymer for efficient catalytic hydrogenation of nitroarenes in water

Small palladium nanoparticles stabilized with phosphine-functionalized PIP displayed high catalytic activity for nitroarenes hydrogenation. Nano-size Pd particles, electron-donation effect of phosphine ligand, and surface wettability account for its excellent catalytic performance.

Facile synthesis of crystalline viologen-based porous ionic polymers with hydrogen-bonded water for efficient catalytic CO2 fixation under ambient conditions.

In this work, we report a series of crystalline viologen-based porous ionic polymers (denoted VIP-X, X = Cl or Br), that have in situ formed dicationic viologens paired with halogen anions and intrinsic hydrogen-bonded water molecules, towards metal-free heterogeneous catalytic conversion of carbon dioxide (CO2) under mild conditions. The targeted VIP-X materials were facilely constructed via the Menshutkin reaction of 4,4′-bipyridine with 4,4′-bis(bromomethyl)biphenyl (BCBMP) or 4,4′-bis(chloromethyl)biphenyl (BBMBP) monomers. Their crystalline and porous structures, morphological features and chemical structures and compositions were fully characterized by various advanced techniques. The optimal catalyst VIP-Br afforded a high yield of 99% in the synthesis of cyclic carbonate by CO2 cycloaddition with epichlorohydrin under atmospheric pressure (1 bar) and a low temperature (40 °C), while other various epoxides could be also converted into cyclic carbonates under mild conditions. Moreover, the catalyst VIP-Br could be separated easily and reused with good stability. The remarkable catalytic performance could be attributed to the synergistic effect of the enriched Br− anions and available hydrogen bond donors –OH groups coming from H-bonded water molecules.

Porous Metallosalen Hypercrosslinked Ionic Polymers for Cooperative CO2 Cycloaddition Conversion

Metallosalen-based porous ionic polymers have the potential to combine the merits of homogeneous organometallics and heterogeneous porous ionic catalysts in carbon dioxide (CO2) cycloaddition conve...

Cobalt-Salen-Based Porous Ionic Polymer: The Role of Valence on Cooperative Conversion of CO2 to Cyclic Carbonate.

Cobalt-salen-based porous ionic polymers, which are composed of cobalt and halogen anions decorated on the framework, effectively catalyze the CO2 cycloaddition reaction of epoxides to cyclic carbonates under ambient conditions. The cooperative effect of bifunctional active sites of cobalt as the Lewis acidic site and the halogen anion as the nucleophile responds to the high catalytic performance. Moreover, density functional theory results indicate that the cobalt valence state and the corresponding coordination group influence the rate-determining step of the CO2 cycloaddition reaction and the nucleophilicity of halogen anions.

A porous ionic polymer bionic carrier in a mixed matrix membrane for facilitating selective CO2 permeability

Inspired by the most efficient CO2 transport across natural biological membranes, a novel bionic channel facilitating CO2 permeation was realized via adding a filtering porous ionic polymer (PIP) in a mixed matrix membrane (MMM). A series of polymer of intrinsic microporosity (PIM-1) based MMMs were fabricated by three pyridine-based PIPs (PIP-Py-X) with different Cl−, Ac−, and BF4− anions as fillers. PIP-Py-X PIPs show highly selective CO2 adsorption capacity and perfect interfacial compatibility with the PIM-1 matrix. More significantly, acting as carriers, the movable anions in the MMMs efficiently facilitated the transport of adsorbed CO2 across the membranes. As a result, the obtained PIM-Py-Ac-15 MMM exhibited an excellent permeability for CO2 of 6205 barrer and a CO2/N2 and CO2/CH4 selectivity of 62.5 and 56.1, respectively, far surpassing the 2008 Robeson upper bound and exceeding most of the reported advanced membranes. As a divertive of PIPs, this work opens a window for designing and fabricating promising MMMs for task-specific membrane separations.

Dual-Ionically Bound Single-Site Rhodium on Porous Ionic Polymer Rivals Commercial Methanol Carbonylation Catalysts.

Novel porous polymers can serve as self-supporting solid carriers and provide abundant coordination or charged sites for single-site metals, and thus are emerging as advanced functional materials in heterogeneous catalysis for various transformations traditionally catalyzed by homogeneous systems. A brief overview of the development of this heterogenization given, including the recent advances regarding electrovalent bonds by employing charged supports represented by porous ionic polymers (PIPs), which is exemplified herein with a novel single-site Rh1 /PIP catalyst, featuring a new active site [Rh(CO)I3 ]2- dual-ionically bound onto a quaternary phosphonium cationic framework polymer, different from the single-ionically bound [Rh(CO)2 I2 ]- in previous studies. Such a unique metal configuration of Rh1 /PIP leads to excellent performance in vapor-phase methanol carbonylation, outperforming commercial homo- and heterogeneous catalysts.

Engineering polyoxometalate anions on porous ionic network towards highly catalytic active noble metal clusters

High surface energy of noble metal clusters (NMCs) with sub-nanometer size (<2 nm) endows their remarkable catalytic activity but naturally increases the risk of deactivation due to aggregation or oxidation. As a result, it is challengeable to construct efficient and stable naked NMCs. Herein, we reported the solvothermal synthesis of polyhedral oligomeric silsesquioxane (POSS) based porous ionic polymers with large surface areas, tunable pore structures and abundant ionic sites that resemble the structure of traditional ionic liquids. A series of highly dispersive and stable NMCs (Pd, Pt, Ru and Rh) were generated on these polymers by modulating their polyoxometalate (POM) anions, attributable to their robust framework and ion-exchange property. These organic cations paired POM anions are found to provide versatile strong interaction towards noble metal species, responsive for the formation and stabilization of NMCs. The obtained Pd clusters effectively catalyzed the solvent-free oxidation of benzyl alcohol with atmospheric dioxygen (O2), affording a high yield of 97% and a huge turnover number (TON) that exceeded 639 times of commercial Pd/C catalyst. The catalyst also exhibited pleasurable reusability and broad substrate compatibility.

Local Environment Structure in Positively Charged Porous Ionic Polymers for Ultrafast Removal of Sulfonamide Antibiotics

Selectivity and efficiency are always the most difficult challenges for adsorption technology, especially for the removal of trace amounts of antibiotics from an aqueous system. We employed the str...

Porous ionic liquid polymer: A reusable adsorbent with broad operating pH range for speciation of nitrate and nitrite

Ionic liquids (ILs) are a class of fluids with unique physicochemical properties employing polymeric substances emerging new materials. Solidification of ILs into porous materials generates porous ionic liquid polymers that combine the unique characteristics of ILs with common porous materials and polymers. In this study, it’s the first time the porous ionic liquid polymer was chosen as a sorbent for extraction and speciation of nitrite and nitrate. Porous IL was prepared through polymerization of 1-allyl-3-methylimidazolium bromide monomers in the presence of azobisisobutyronitrile (AIBN) and crosslinking of ethylene glycol dimethyl acrylate (EGDMA). Parameters affecting the adsorbent performance were optimized. Under the optimal conditions, correlation coefficient (R2) was 0.9996 and LOD was 0.1 µg L−1. This method presented the linearity in the concentration range between 0.1–100 µg L−1 and the relative standard deviation was 3.2%. Finally, the adsorption behavior of the obtained sorbent for nitrate and nitrite determination in various real samples was evaluated. The result indicates that the porous ionic liquid polymer showed high adsorption capacity (233 mg g−1). The convenient preparation of the porous ionic liquid material, as well as high adsorption capacity for anionic pollutants predicted its broad application potential in anion removal materials.

Ionic Porous Organic Polymers Based on Functionalized Tetraarylborates.

Lithium tetrakis(4-boronatoaryl)borates were subjected to polycondensation reactions with selected polyhydroxyl monomers such as 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) and 2,3,6,7-tetrahydroxy-9,10-dimethylanthracene (THDMA). Obtained boronate-type ionic porous polymers TAB1–4 were characterized by PXRD, 6Li and 11B magic-angle spinning nuclear magnetic resonance (MAS NMR), FT-IR, SEM, and TGA. They exhibit relatively good sorption of H2 (up to 75 cm3/g STP), whereas N2 uptake at 77 K for lower pressure range is relatively poor (up to 50 cm3/g STP below P/P0 = 0.8). In addition, the effect of elongation of aryl arms in the tetraarylborate core on the materials’ properties was studied. Thus, it was found that replacement of the 4-boronatophenyl with 4-boronatobiphenylyl group has a negative impact on the sorption characteristics.

Adsorption-enhanced oxidative desulfurization by a task-specific pyridinium-based porous ionic polymer

An adsorption-enhanced catalytic reaction approach was proposed to improve the kinetics of the oxidative desulfurization in which a task-specific porous ionic polymer (PIP) was designed to act as both of organosulfur adsorbent and catalyst support. Through a simple one-pot crosslinking of simultaneous quaternization and Friedel-Crafts alkylation reactions, the hierarchical pyridinium-based PIP of [PPYX]Cl was fabricated, which exhibited an outstanding adsorption capacity of dibenzothiophene (DBT) of 35.1 mgS g−1. When it was used as the support, its large surface area and positive charged network assured highly dispersion of (phosphotungstic acid) HPW species, resulting in HPW/[PPYX] hybrid catalysts. Among them, HPW/[PPYX]-0.5 outperformed that only within 45 min, a complete conversion of 100 mgS L−1 DBT model oil was accomplished under the optimized ODS conditions. Moreover, it also showed an excellent recycling stability that almost no loss of the catalytic reactivity after ten cycles due to the good affinity between HPW and [PPYX]Cl. Therefore, through this successful case of adsorption-enhanced oxidative desulfurization, PIPs could be promising supports for producing highly efficient heterogeneous catalysts.

Confined Ionic Liquid in an Ionic Porous Aromatic Framework for Gas Separation

Ionic liquids (ILs) and porous frameworks are commonly employed in gas separation, but rarely together. To leverage their combined advantages, we designed a novel system comprising an ionic liquid inside a charged porous-polymer framework. A positively charged ionic porous aromatic framework was impregnated with an ionic liquid to confine the cations and anions inside the polymeric framework via electrostatic interactions. Molecular dynamics and free energy simulations were performed to determine the solubility, diffusivity, and hence permeability of CO2 and CH4 through the composite material. We found that the polymeric framework introduces nanoscale space in the confined IL, improving gas solubility, while the IL promotes gas transport in the porous structure. The confinement impacts CO2 and CH4 very differently regarding their solubility and diffusivity. Through tuning of the ionic-liquid loading, both high CO2 permeability and high CO2/CH4 selectivity could be achieved, overcoming the Robeson upper bound. This work highlights the advantages of confined ionic liquids in an ionic porous-polymer framework in enhancing selective gas separation.

Viologen‐Hypercrosslinked Ionic Porous Polymer Films as Active Layers for Electronic and Energy Storage Devices

AbstractOver the past decades, numerous scientists have focused on designing complicated monomers, developing new synthesis protocols, and optimizing chemical structures for realizing high‐performance organic or polymer electronics and energy storage devices. However, much less attention has been paid to ionic‐ and radical‐rich porous organic films, which are essential components of aforementioned devices. In this study, an air‐stable, large‐area, free‐standing, and viologen‐linked ionic porous polymer (denoted as IPP‐V) film is developed in situ through electrochemical polymerization. This film is applied to a device by sandwiching it between indium tin oxide (ITO) and Au (i.e., ITO/IPP‐V/Au); the device exhibits a memristive behavior with an ON–OFF current ratio of ≈2. After the IPP‐V film is subjected to thermal pyrolysis at 500 °C, the as‐produced film (denoted as IPP‐V‐500) acts as an active material for an in‐plane micro‐supercapacitor and exhibits a high volumetric capacitance level of up to 4.44 F cm−3. This work not only offers a new and convenient strategy toward large‐area ionic porous polymer films for memristor, but also provides a new porous polymer derived carbon film for energy storage.

Fabrication of porous ionic liquid polymer as solid-phase microextraction coating for analysis of organic acids by gas chromatography – mass spectrometry

A kind of porous ionic liquid polymer was designed as coating material for solid-phase microextraction (SPME) fibers to extract polar organic acids. The synthesized ionic liquids (1-vinyl-3-(4-vinyl-benzyl)imidazolium chloride) were polymerized in the presence of azobisisobutyronitrile (AIBN), and subsequently coated on stainless steel wires with physical adhesion. To guarantee the adhesion between coating and the surface of stainless steel wires, micro-wave induced plasma was applied to modify the stainless steel wires. The derivatives of extracted organic acids were analyzed by gas chromatography combined with mass spectrometry (GC-MS) with N-tert-Butyldimethylsilyl-N-methyltrifluoroacetamide (MTBSTFA) as the derivatization reagent. Under the optimal condition, a calibration study was carried out to evaluate the performance of the SPME fibers. The calibration curves were linear (R2>0.99) in the range from 0.01μg/ml to 1μg/ml for six organic acids. Detection limits were detected down to 0.07ng/ml. To further validate the extraction efficiency of the fibers, experiments were conducted in comparison with commercial fibers. Lower LOD and LOQ values were obtained by the in-house fabricated fibers especially for polyatomic acids. Good repeatability (RSD≤16%) and fiber-to-fiber reproducibility (RSD≤20%) were obtained. The acceptable recovery of the spiked grape wine samples ranged from 78.19% to 98.11%. Additionally, long lifetime and good durability of the fibers have been demonstrated. The performance of the established SPME-GC-MS method for analysis of organic acids was shown to be greatly improved in comparison to the direct HPLC/CE method or other SPME materials as reported in the literature. In summary, a feasible and effective approach has been demonstrated to fabricate the in-house fabricated fibers based on porous ionic liquid polymers, which were proved to be advantageous and sensitive for extraction of polar organic acids. Simultaneously, application of the SPME derivatization GC-MS method for analysis of organic acids has been successfully verified as feasible and reliable.

One-pot solvothermal synthesis of hypercrosslinked porous ionic polymer and its catalytic activity

The hypercrosslinked porous ionic polymer has been synthesized via one-pot polymerization and quaternization of vinyl pyridine and chloromethyl styrene under solvothermal condition. The effects of solvents and synthetic process on the polymer structure were investigated. Polymer from n-butanol showed the highest BET surface area of 555.6 m2/g. The catalytic activities were investigated though the aza-Michael addition and the results showed that the polymer owned even higher activity than homogenous ionic liquid. The high BET surface area, high catalytic activity and high stability made the polymer hold great potential for green chemical processes.

Metallosalen-Based Ionic Porous Polymers as Bifunctional Catalysts for the Conversion of CO2 into Valuable Chemicals.

A series of new metallosalen-based ionic porous organic polymers (POPs) were synthesized for the first time using a simple unique strategy based on the free-radical copolymerization reaction. Various techniques were used to characterize the physicochemical properties of these catalysts. These well-designed materials endowed high surface area, hierarchical porous structures, and enhanced CO2 /N2 adsorptive selectivity. Moreover, these POPs having both metal centers (Lewis acid) and ionic units (nucleophile) could serve as bifunctional catalysts in the catalytic conversion of CO2 into high value-added chemicals without any additional co-catalyst under mild and solvent-free conditions, for example, CO2 /epoxides cycloaddition and Nformylation of amines from CO2 and hydrosilanes. The results demonstrated that the irregular porous structure was very favorable for the diffusion of substrates and products, and the microporous structural property resulted in the enrichment of CO2 near the catalytic centers in the CO2 -involved transformations. Additionally, the superhydrophobic property could not only enhance the chemoselectivity of products but also promote the stability and recyclability of catalysts.

Porous Ionic Polymers as a Robust and Efficient Platform for Capture and Chemical Fixation of Atmospheric CO2.

Direct use of atmospheric CO2 as a C1 source to synthesize high-value chemicals through environmentally benign processes is of great interest, yet challenging. Porous heterogeneous catalysts that are capable of simultaneously capturing and converting CO2 are promising candidates for such applications. Herein, a family of organic ionic polymers with nanoporous structure, large surface area, strong affinity for CO2 , and very high density of catalytic active sites (halide ions) was synthesized through the free-radical polymerization of vinylfunctionalized quaternary phosphonium salts. The resultant porous ionic polymers (PIPs) exhibit excellent activities in the cycloaddition of epoxides with atmospheric CO2 , outperforming the corresponding soluble phosphonium salt analogues and ranking among the highest of known metal-free catalytic systems. The high CO2 uptake capacity of the PIPs facilitates the enrichment of CO2 molecules around the catalytic centers, thereby benefiting its conversion. We have demonstrated for the first time that atmospheric CO2 can be directly converted to cyclic carbonates at room temperature using a heterogeneous catalytic system under metal-solvent free conditions. Moreover, the catalysts proved to be robust and fully recyclable, demonstrating promising potential for practical utilization for the chemical fixation of CO2 . Our work thereby paves a way to the advance of PIPs as a new type of platform for capture and conversion of CO2 .