Porous Organic Polymer Materials Research Articles

CTAB modified metakaolin-based geopolymer microspheres for the selective adsorption and recovery of TcO4−/ReO4−

With the increase of radioactive wastewater, it is a major challenge to efficient removal of TcO4− from radioactive wastewater. So far, cationic metal organic frameworks (MOFs), cationic covalent organic frameworks (COFs), cationic polymeric networks (CPNs) and porous organic polymer materials (POPs) can remove TcO4− efficiently, but the cumbersome preparation process and high cost limit their practical applications. Herein, an efficient and low-cost CTAB-modified metakaolin-based geopolymer microspheres (CTAB@MGMs) with excellent adsorption properties for ReO4− is simply and rapidly synthesized by dispersion-pelletizing-solidification and vacuum infusion methods. CTAB@MGMs has fast adsorption kinetics (equilibrium in 10 min), a wide pH application range (2–10) and high selectivity in competing ions (PO43−, SO42−, NO3−, Cl−) and real waters (tap water, surface water, seawater). Importantly, complete desorption of the adsorbed sample can be realized by ethanol and MGMs can be recycled without performance decay. Meanwhile, ethanol recycling was achieved by spin-evaporation of desorption solution and a novel compound CTA-ReO4 was generated. We have analyzed and reported the crystal structure of CTA-ReO4 (CCDC Numbers: 2282273) for the first time and revealed the mechanism that ReO4− is removed by electrostatic and coordination synergism with quaternary ammonium salts after ion exchange. CTAB@MGMs is a low-cost, novel and reusable adsorbent with potential use for the removal of TcO4− from radioactive wastewater.

Triazine-containing porous organic polymers from Diels-Alder reactions for efficient molecular adsorption and photocatalytic degradation

As a reversible and simple synthetic strategy, Diels-Alder (DA) reactions were recently exploited for the construction of porous organic polymers (POPs) with diverse structures and functions, which hold the promise to synthesize functional POPs in large scale. However, these methods typically need high polymerization temperature, and the structural diversity is limited for their practical applications. In this work, a series of DA-POPs were successfully synthesized via the Diels-Alder reactions of furan- and alkynyl-functionalized monomers. To reduce the activation energy of the reaction, we introduced 1,3,5-triazine moiety to alkynyl-functionalized monomers, which substantially lowered the polymerization temperature to 120 °C. Leveraging the reported photoelectric activity from triazine moiety, we applied these POPs materials to the adsorption and photocatalytic degradation of the organic dye Rhodamine B, exhibiting remarkable adsorption and degradation ability. Photophysical tests further elucidated the degradation mechanism and corroborated the photocatalytic application potential of these DA-POPs. This work brings a new synthetic strategy for the elaboration of POPs for reducing environmental pollution via photocatalytic waste degradation.

Synthesis of phenothiazine-based porous organic polymer and its application to iodine adsorption

At present, porous organic polymer materials (POPs) have become a popular topic in the research of iodine adsorption materials. Herein, we report an electron-rich porous organic polymer (PTZ-TPC-MA), obtained by Schiff base polycondensation reaction between melamine(MA) and aldehyde monomer with high yield and simplicity. It structures was characterized through FT-IR, 13C CP/MAS NMR and other material analysis measurements. The PTZ-TPC-MA material, being abundant in N and S heteroatoms, the adsorption capacity for iodine vapor, reaching up to 198.1 wt%,and it demonstrates removal rate of 79.8% for iodine from hexane solution. In addition, the recyclability tests have also confirmed its excellent reusability. The material showed better iodine capture capacity for gaseous iodine and iodine in solution. Thus PTZ-TPC-MA material thus emerges as an optimal absorber for iodine capture, offering an effective strategy to solve environmental problems.

Recent Progress of Amorphous Porous Organic Polymers as Heterogeneous Photocatalysts for Organic Synthesis

AbstractThe establishment of green and environmental friendly sunlight‐driven organic reactions has received increasing attention since the 21st century. By virtue of their functional designability, micromesoporous structure, and thermal/chemical stability, porous organic polymers (POPs) have exhibited enormous promise in photocatalytic organic reactions as ideal potential alternatives to conventional small molecule and inorganic semiconductor catalysts. In particular, amorphous POPs are simplified in terms of preparation conditions and process flow. Herein, various amorphous POP materials based on polymers of intrinsic microporosity, hypercrosslinked polymers, conjugated microporous polymers, and porous aromatic frameworks are reviewed, while typical synthetic strategies are briefly introduced. It also highlights an overview of the research progress in photocatalytic oxidation, coupling, reduction, cycloaddition, and polymerization reactions at home and abroad in recent years. Finally, the challenges and prospects for future research on amorphous POPs are presented.

In situ synthesis of a spherical covalent organic framework as a stationary phase for capillary electrochromatography

Covalent organic frameworks (COFs) are a novel type of crystalline porous organic polymer materials recently developed. It has several advantages in chromatographic separation field, such as high thermal stability, porosity, structural regularity, and large specific surface area. Here, a novel spherical COF 1,3,5-tris(4-aminophenyl)benzene (TAPB) and 2,5-bis(2-propyn-1-yloxy)-1,4-benzenedicarboxaldehyde (BPTA) was developed as an electrochromatographic stationary phase for capillary electrochromatography separation. The COF TAPB-BPTA modified capillary column was fabricated via a facile in situ growth method at room temperature. The characterization results of scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, and X-ray diffraction (XRD) confirmed that COF TAPB-BPTA were successfully modified onto the capillary inner surface. The electrochromatography separation performance of the COF TAPB-BPTA modified capillary was investigated. The prepared column demonstrated outstanding separation performance toward alkylbenzenes, phenols, and chlorobenzenes compounds. Furthermore, the baseline separations of non-steroidal anti-inflammatory drugs (NSAIDs) and parabens with good efficiency and high resolution were achieved. Also, the prepared column possessed satisfactory precision of the intra-day runs (n = 5), inter-day runs (n = 3), and parallel columns (n = 3), and the relative standard deviations (RSDs) of the retention times of tested alkylbenzenes were all less than 2.58%. Thus, this new COF-based stationary phase shows tremendous application potential in chromatographic separation field.

One-step fabrication of nitrogen-rich linear porous organic polymer-based micron-sized sphere for selective enrichment of glycopeptides

In this work, nitrogen-rich linear porous organic polymers (POPs) were designed to improve glycopeptides enrichment efficiency in HILIC. Two kinds of novel POPs (CH-pPAL and CH-mPAL) were one-step prepared via the Schiff-base condensation reaction and intermolecular hydrogen-bonded using a flexible amine monomer (carbohydrazide, CH) to react with two aldehyde monomers, p-phthalaldehyde (pPAL) and m-phthalaldehyde (mPAL), respectively. The specific surface area of CH-pPAL and CH-mPAL was 238 and 232 m2 g−1, respectively. Based on the hydrogen-bond interaction, several narrow peaks existed in the PXRD patterns. Particularly, micron-sized spherical CH-pPAL possessed a honeycomb-like orderly tunnel structure. The contact angle of CH-pPAL and CH-mPAL severally was 35.4° and 28.8°, respectively, indicating excellent hydrophilicity of as-synthesized POPs. They both demonstrated high sensitivity and high adsorption capacity in glycopeptides enrichment. The 851 and 794 unique glycopeptides derived from 170 and 200 N-glycosylated proteins were identified after the enrichment by CH-pPAL and CH-mPAL within three independent replicates of proteins extracted from human serum, respectively. Therefore, these CH-based hydrophilic POP materials would be applied in the enrichment and identification of low-abundance N-linked glycopeptides from complicated biological samples.

Adsorption of CO2 by amine-modified novel nanomaterials

The greenhouse effect has a serious impact on our living environment. The development of novel amine-modified porous organic polymer materials is of great significance to achieve the capture of greenhouse gas CO2. In this study, hexadecyltrimethyl ammonium bromide (CTAB) was used as template, resorcinol formaldehyde resin adhesive was synthesized by polycondensation reaction between 1,3 resorcinol and formaldehyde, and ethyl orthosilicate (TEOS) was used as inorganic precursor (prepared by reaction of silicon tetrachloride and ethanol). Choline, tetramethylammonium hydroxide, plant growth regulators, herbicides, strong base anionic and cationic resins, dye levelling agents, and a range of basic colours all are manufactured from trimethylamine. Trimethylamine is recognized by gas sensors used it to check for seafood freshness. One-step sol-gel method was used. A novel nanoporous carbon silicon material (NNCMR) was synthesized. Using the composite porous material as a carrier, the isomers triethylene tetraamine (TETA) and tri (2-aminoethyl) amine (TAEA) as modifiers, respectively. New amine-modified porous carbon-silicon materials (NNCMR-TETA-X and NNCMR-TAEA-X) were prepared by impregnation method. Triethylenetatramine (TETA) is an orphaned medication that treats copper excess in tissues. It is a selective divalent Cu(II) chelator. Trientine, a salt form of D-penicillamine, was released in 1969 as a substitute for D-penicillamine. The results show that this kind of material has rich microporous structure and ordered mesoporous structure, and realizes the framework fusion of carbon and silicon oxide, and uniformly loads the amine material. NNCMR-TETA-50 showed the best adsorption performance among the new nanoporous carbon and silicon materials, with a maximum adsorption capacity of 4.21 mmol/g. The composite porous materials with different amine structures as modifiers have different effects on CO2 capture performance. In the presence of water vapor, NNCMR-TAEA-50 showed the best adsorption performance, with a maximum adsorption capacity of 4.96 mmol/g, since the tertiary amine group could not effectively capture CO2 in the absence of water vapor, but could work well in the presence of water vapor. This can help us design suitable adsorbent materials for CO2 capture in different practical applications. At the same time, the new nanoporous carbon silicon material has good thermal stability and recycling.

Porous organic polymers involving chloro-substituted peryleneimide for photocatalytic water oxidation under visible light irradiation

Porous organic polymers (POPs) have become a class of promising photocatalytic materials for solar water splitting due to their high structural adjustability, multiple active sites and high stability against water corrosion. However, because of the complex transfer process involved and the large overpotential required for oxygen evolution reaction (OER), the studies about POP type semiconductor photocatalysts for the efficient photocatalytic OER are very few. Here, we design and prepare a novel POP type photocatalyst 4Clper-POPs constructed by chlorine-modified peryleneimide and aromatic aldehyde that can significantly improve the photocatalytic OER activity. The band gap of as-synthesized 4Clper-POPs is 1.28 eV, indicating that they possess a wide light absorption range extended to the near-infrared region. Moreover, 4Clper-POPs exhibit a large oxidation potential to drive the photocatalytic OER. More importantly, combining the results of experiments and the first-principles calculations, under the condition of AgNO3 as the electronic sacrificial agent, it can be obtained that the chlorine element in the 4Clper-POPs can effectively accumulate AgNO3 and the reduced Ag nanoparticles (NPs), facilitating the rapid transport of electrons. Under visible light, 4Clper-POPs exhibit the highest average O2 evolution efficiency (714.17 μmol g-1h−1) with 5 wt% Co2+ loaded among all the reported POP materials used for the OER. Our findings provide design ideas of POP type semiconductor photocatalysts for the efficient OER.

Constructing Polyimide Aerogels with Carboxyl for CO2 Adsorption.

In this study, mesoporous polyimide aerogels with carboxyl were successfully synthesized by the co-polymerization method at room temperature from pyromellitic dianhydride and 1,3,5-triaminophenoxybenzene, 3,5-diaminobenzoic acid, and 2,2′-dimethyl-4,4′-diaminobiphenyl. Compared to previously reported porous organic polymer materials, this aerogel has the advantage of a simple and efficient synthesis method. The thermal decomposition temperatures of the obtained polyimide aerogels are all above 400 °C and have excellent thermal stability. Among them, the largest specific surface area is 62.03 m2/g. Although the surface area of this aerogel is not large enough, it has considerable CO2 adsorption properties. The adsorption capacity of CO2 is up to 11.9 cm3/g, which is comparable to those of previously reported porous materials. The high CO2 adsorption is attributed to the abundance of carboxyl groups in the polyimide networks. The mild and convenient synthesis method and high CO2 adsorption capacity indicate that the polyimide aerogel with carboxyl is suitable as a good candidate material for CO2 adsorption.

Redox‐Active Porous Organic Polymers for Energy Storage

This review introduces synthesis and energy storage applications of recent redox‐active porous organic polymer (POP) materials. First, various redox‐active molecular systems were summarized and then, synthetic examples of redox‐active POP bearing the redox‐active molecular moieties were described. Various synthetic strategies based on diverse coupling reactions of building blocks were described. In addition, postsynthetic modification strategies for the preparation of redox‐active POP were described. Second, structures and electrochemical features of battery and pseudocapacitor devices were introduced. Then, electrochemical performance of various redox‐active POP materials was summarized and described. Finally, merits and weak points of redox‐active POPs as electrode materials were discussed and future research direction was suggested.

Iron oxide modified N-doped porous carbon derived from porous organic polymers as a highly-efficient catalyst for reduction of nitroarenes

Fabrication of cost-effective non-noble metal-based catalysts is significant for heterogeneous catalysis. Here, we prepared a porous organic polymer (POP) through the facile condensation of p-phenylenediamine with ferrocene carboxaldehyde, and then the ferrocene-functionalized POP material was carbonized under inert atmosphere, obtaining the γ-Fe2O3 nanoparticles (NPs) modified N-doped porous carbon catalyst (γ-Fe2O3/NPC). Various characterizations (such as XRD, BET, TEM and XPS etc.) indicated that the obtained γ-Fe2O3/NPC catalyst exhibits unique structural properties with uniformly dispersed γ-Fe2O3 species, porous morphology, and N-doped defective amorphous carbon. The γ-Fe2O3/NPC catalyst shows excellent activity in the catalytic reduction of nitroarenes with hydrazine hydrate as reductant. The synergistic effect between γ-Fe2O3 NPs and N-doped porous carbon improve the hydrazine hydrate adsorption and activation for active hydrogen atoms production, which is beneficial for nitroarenes reduction. Moreover, the γ-Fe2O3/NPC catalyst could be easily recycled by using a magnet and reused without obviously loss of catalytic activity. Therefore, this work should provide a useful platform for designing and fabricating stable non-noble metal NPs based catalysts derived from POP materials that have potential for various catalytic applications.

Facile synthesis of anionic porous organic polymer for ethylene purification

The removal of acetylene from ethylene is of vital significance in the petroleum and chemical industry, the presence of trace acetylene impurities in ethylene polymerization process could lead to the interruption of ethylene polymerization. Herein, we construct a new anionic porous organic polymer using potassium tetraphenylborate via Friedel–Crafts alkylation reaction under mild conditions. The resulting material, APOP, possesses good thermal stability and a decent BET surface area, as exemplified by thermogravimetric analysis measurement and nitrogen gas sorption experiment. Acetylene and ethylene adsorption isotherms reveal that APOP has a higher adsorption capacity of acetylene than that of ethylene under same conditions. Ideal adsorbed solution theory calculations and breakthrough experiments both demonstrate that APOP is capable of selective adsorption of acetylene over ethylene. To the best of our knowledge, APOP represents the first anionic porous organic polymer material capable of selective adsorption of acetylene over ethylene, and the exploration of APOP may provide a new way for these key gas separations using ionic porous organic polymer materials.

Ultrafine palladium nanoparticles confined in core–shell magnetic porous organic polymer nanospheres as highly efficient hydrogenation catalyst

The development of porous organic polymer (POP)-based materials with controllable structures is highly desirable for catalysis, drug delivery, and chemical adsorption. In this work, we prepared unique porous magnetic core–shell POP nanospheres (Fe3O4@PDA@POP) through a facile strategy. These nanospheres contained a core of magnetic Fe3O4 nanoparticles (NPs), a hydrophilic intermediate layer of dopamine and a POP outer layer. The Fe3O4@PDA@POP showed high porosity, making it an ideal supporting material for fabricating ultrafine and highly dispersed noble-metal NPs (NMNPs). Thus, highly dispersed ultrafine Pd NPs (1.5–2.1 nm) were confined and stabilized within the pores of Fe3O4@PDA@POP via a reverse double-solvent approach (RDSA) to obtain Fe3O4@PDA@POP@Pd catalyst. The Fe3O4@PDA@POP@Pd-2.5% catalyst showed excellent catalytic performance and recyclability towards the hydrogenation of nitrobenzene, alkenes, and alkynes. Hence, this work can pave the way for the development and application of functionalized POP materials to construct efficient catalytic systems.

Fabrication of microporous polyimide networks with tunable pore size and high CO2 selectivity

Developing porous organic polymer materials with plenty micropores is of great importance for highly selective CO2 capture under ambient conditions. Here, to tune the pore size, two novel microporous hyperbranched polyimide networks, in which the distance between the polymer skeleton and crosslinking points is different, are successfully prepared by a two-step pathway combining polymerization and crosslinking reaction. It is intriguingly found that both porosity and CO2 sorption performance of microporous hyperbranched polyimides can be finely tuned by reducing the distance between the polymer skeleton and crosslinking points from PEPHQDA-HBPI-CL to PEQDA-HBPI-CL. The micropore size decrease from 1.18 nm to 0.86 nm, and CO2 adsorption capacity increase from 6.38 to 6.51 wt% (298 K and 1 bar). More excitingly, the PEQDA-HBPI-CL demonstrates the high CO2/N2 and CO2/CH4 selectivity up to 109 and 15 (273 K, 1 bar) according to the Henry's law, which are superior to those of many other microporous organic polymers and among the best results for porous inorganic/ organic materials. This work reveals that the shorter-distance between the polymer skeleton and crosslinking points is in favor of fabricating microporous hyperbranched polyimide networks with abundant smaller micropore and high CO2 selectivity, which are crucial importance for the CO2 capture and storage.

Ultra-fine Pd nanoparticles confined in a porous organic polymer: A leaching-and-aggregation-resistant catalyst for the efficient reduction of nitroarenes by NaBH4

Porous organic polymers (POPs) containing nitrogenous substituents have potential practical applications as heterogeneous catalysts based upon controlled porous structure and surface-anchored noble metal nanoparticles (NMNPs). In this work we prepared a POP material from piperazine and cyanuric chloride starting materials (PC-POP). The PC-POP material contains numerous triazinyl moieties, thus rendering the pores hydrophobic. Subsequently, by means of a novel reverse double-solvent approach (RDSA), microdroplets of Pd(AcO)2/CH2Cl2 were introduced into the hydrophobic pores of PC-POP in an aqueous environment; Pd(II) was rapidly reduced by NaBH4 to form ultra-fine Pd NPs and confined within the pores of PC-POP at high dispersity. The extensive porosity and dispersity of the Pd NPs made the active sites readily accessible, and led to efficient mass transfer. Thus, Pd@PC-POP exhibits superior catalytic performance in catalytic reduction of various nitroarenes. Furthermore, Pd@PC-POP has excellent recyclability, without significant loss of activity nor leaching of Pd active sites during 10 successive reaction cycles. This work points to a practical and cost-effective approach to preparation of POP materials, and also for confining ultra-fine NMNPs in POPs for use as catalysts.

How to Design Porous Organic Polymers as Gas Capture?

In recent years, the design and construction of porous organic polymers (POPs) have attracted significant interest from scientists because of their extensive potential applications in the areas of gas storage, separation, heterogeneous catalysis and sensors, etc. [1]. POP materials are often prepared via the direct synthesis methodology because this approach has characteristic advantages: a high utilization efficiency of the starting materials and facile formation of micro pores [2]. In this methodology, two important issues should be addressed. One is selecting proper chemical synthesis methods to efficiently link the building blocks together over a broad range. Among various methods, Sonogashira– Hagihara reaction is a typical class of routes and has been well established for the synthesis of POP materials [3] especially conjugated micro porous polymers (CMPs), which combine micro porosity and πconjugated bond and have a great promise in the range of applications such as lightharvesting, photo catalysis and sensing, except the typical usage in gas storage [4]. Another is the choice of the correct monomers, which are crucial to the formation of porous networks with adequate stability and largely influence the various properties of the final products.

Electroactive Co(iii) salen metal complexes and the electrophoretic deposition of their porous organic polymers onto glassy carbon.

This paper reports the CO2 electroreduction properties of three bis-bromo Co(iii) salen metal complexes and their Porous Organic Polymers (POPs) as a platform for using the salen core as a multi-electron reducing agent. Although Co(iii) salen metal complexes have been studied extensively for their chemical catalysis with CO2, their electrochemical behaviour, particularly their reduction, in the presence of CO2 is much less explored. The discrete Co(iii) complexes enabled the reduction of CO2 to CO in faradaic efficiencies of up to 20%. The reductive electrochemical processes of Co(iii) salen complexes are relatively unknown; therefore, the mechanism of reduction for the complexes was investigated using IR and UV-Vis-NIR spectroelectrochemical (SEC) techniques. The discrete bis-bromo salen complexes were incorporated into POPs with tris-(p-ethynyl)-triphenylamine as a co-ligand and were characterised using solid state NMR, IR, UV-Vis-NIR and Field Emission Scanning Electron Microscopy (FE-SEM). The POP materials were electrophoretically deposited onto glassy carbon under milder conditions than those previously reported in the literature. Direct attachment of the POP materials to glassy carbon enabled improved solid state electrochemical analysis of the samples. The POP materials were also analysed via SEC techniques, where a Co(ii/i) process could be observed, but further reductions associated with the imine reduction compromised the stability of the POPs.

Synthesis and Fluorescent Sensing Application of Porous Organic Polymer Materials

Synthesis and Fluorescent Sensing Application of Porous Organic Polymer Materials

Structural design, preparation and characterization of light, isotropic and robust statically determined organic frameworks as reusable adsorbents

Using (bi)adamantane “knots” and p-phenylene “rods” as building blocks, statically determined organic frameworks, viewed and termed as porous organic polymers (POP) were synthesized by Suzuki coupling polycondensation with high yields, 85–94%. The saturation of the polymer linking knot and rod groups was determined by FT-IR and 13C NMR spectroscopy. The POP material particles were light in weight (volumetric density of 0.1–0.24 g cm−3), porous (total pore volume of >0.35 cm3 g−1), and spherical in shape. The obtained POP materials were highly stable in its structural integrity, demonstrating both exceptional thermal stability upon heating at high temperatures and excellent chemical resistance to strong acid and base. In addition, X-ray scattering data indicated that the POP structures were amorphous in a long spacing distance (2–600 nm), being in an isotropic packing configuration with diffusive scattering contributed from all directions. The proof-to-concept of building POP structure on the molecular level in the form of multitopic knots and rods bridges paves the road for producing light, stable, and porous polymers structures with strong chemical bonds being effective in all directions. The CH4 and CO2 adsorption capacity of the obtained POPs at 273 K and 1 bar (1.4–2.3 wt% and 10.5–15.1 wt%, respectively) are comparable to many well-known porous polymer frameworks. Notably, the total uptake capability of aliphatic (n-hexane) and aromatic (benzene and toluene) organic vapors were maintained by a simple regeneration treatment, i.e., heating samples at 200 °C under vacuum. The adsorption results suggest their potential applications for gas storage and toxic organic vapor removal as reusable and thermochemically stable materials.

Synthesis of tunable porosity of fluorine-enriched porous organic polymer materials with excellent CO2, CH4 and iodine adsorption

We herein report the construction of four the novel fluorine-enriched conjugated microporous polymers (FCMP-600@1-4), which have permanent porous structures and plenty of fluorine atoms in the skeletons as effective sorption sites. Among them, FCMP-600@4 shows considerable adsorption capacity of CO2 of 5.35 mmol g−1 at 273 K, and 4.18 mmol g−1 at 298 K, which is higher than the reported values for most porous polymers. In addition, FCMP-600@1-4 display high selectivity of CO2/N2 and high CH4 uptakes.