Hypercrosslinked Polymers Research Articles

Donor–acceptor iron phthalocyanine-based hyper-crosslinked polymers with a modulated electronic structure for efficient oxygen reduction reaction in aluminum–air batteries

Poly-FePc-based HCPs with TTF modification are constructed and applied as ORR catalyst for Al–air batteries. The donor–acceptor structure was incorporated into poly-FePc-HCP to achieve structural and electronic regulation.

Insertion of CO2 to 2-methyl furoate promoted by a cobalt hypercrosslinked polymer catalyst to obtain a monomer of CO2-based biopolyesters

2,5-Furan Dicarboxylic methyl Ester (FDME), a highly valued monomer for the synthesis of biobased polyesters, has been prepared through a new synthetic strategy that consists of the direct carboxylation of...

Green synthesis of hypercrosslinked polymers for CO2 capture and conversion: recent advances, opportunities, and challenges

Hypercrosslinked polymers and the resultant carbon materials are promising platforms for CO2 capture and conversion, because of their high specific surface areas, and modifiable and accessible surface functionalities.

Enhanced 5-hydroxymethylfurfural production from cellulose in monophasic molten salt hydrate: Insights into the effect of catalyst acidity on conversion

Production of 5-HMF from cellulose is a promising approach for advanced bio-fuels preparation, but the degradation of active 5-hydroxymethylfurfural (5-HMF) is a critical challenge affecting 5-HMF selectivity. To address this issue, biphasic reaction system consisting of water and organic solvent is generally used to in-situ extract 5-HMF into organic phase to inhibit product degradation. Despite the high 5-HMF selectivity achieved in biphasic system, low product concentration and difficulty in separation restrict its industrial applications. Molten salt hydrate (MSH) is unique in cellulose conversion and 5-HMF preservation. In this work, MSH of LiBr was used as monophasic solvent for cellulose conversion and an acidity tunable solid acid AlSiO-x was used as the catalyst. It was found that a relatively high 5-HMF yield of 44.5% together with carbon balance of 75.0% were obtained at 170 °C for 20 min, which is higher than the results ever reported. Importantly, this work proved that the ratio of total Brønsted to Lewis acid sites on solid acid is the key issue affected 5-HMF yield. After reaction, solid acid can be recycled for more than 5 times without catalytic performance decline, and the dissolved 5-HMF can be sufficiently separated from MSH via hyper cross-linked polymer (HCP) adsorption.

Vapor-phase postsynthetic amination of hypercrosslinked polymers for efficient iodine capture

Hypercrosslinked polymers (HCPs) with large surface areas, high intrinsic porosities and low production costs may be available platforms for iodine capture. However, the lack of iodine-philicity binding sites limits their adsorption capacity. Here we use vapor-phase postsynthetic amination strategy to introduce electron-donating amino groups into the prefabricated HCPs for enhancing their iodine capture performance. Through simple vapor-phase exposure, the halogen-containing HCPs can be grafted by amines through nucleophilic substitution toward chloro groups. Combining with the abundant amino groups and high porosities, the amino-functionalized porous polymers show substantially increased iodine adsorption capacity, about 221% as that of original one, accompanied by excellent recyclability. Mechanism investigations reveal the key roles of the electron-donor amino groups and π-conjugated benzene rings along with structure characteristics of porous polymer frameworks in iodine capture. Moreover, this vapor-phase amination strategy shows good generality and can be extended to various amines, e.g., ethylenediamine, 1,3-diaminopropane and diethylenetriamine. Our work proves that this simple vapor-phase postsynthetic functionalization strategy may be applied in other porous polymers with wide application prospects in adsorption, separation and storage.

Transforming waste polyurethane foam into high value-added hyper-crosslinked polymer for efficient removal of multiple contaminants from wastewater

Waste plastics upcycling and wastewater remediation are environmental issues of global concern that need to be solved urgently. In this study, waste polyurethane foam (PUF) was used as raw material to prepare a high value-added hyper-crosslinked polymer (HCP-PUF) via Friedel - Crafts alkylation reaction with 1,4-p-dichlorobenzyl as external cross-linker. HCP-PUF exhibited high specific surface areas of 942.20 m2/g and abundant pore volumes of 1.03 cm3/g. The maximum adsorption capacities of HCP-PUF for diclofenac sodium (DS) and Congo red (CR) reached to 248.76 mg/g and 1811.04 mg/g at 298 K, respectively. The relatively stable adsorption performance during continuous five cycles experiments suggested the excellent recyclability of HCP-PUF. And the HCP-PUF can be considered as a broad-spectrum adsorbent toward other pollutants including tetracycline, bisphenol A, rhodamine B, Ni2+ and Cu2+. Furthermore, the excellent adsorption performance for DS and CR in actual wastewater indicated that the HCP-PUF had a wide range of application prospects. Hence, this work provided a new pathway for the high-value conversion of waste PUF and prepared an efficient adsorbent for the removal of multiple pollutants from wastewater, embodying the environmental concept of treating waste with waste.

Palladium(II)-immobilized Triptycene based Hypercrosslinked Polymers: An Efficient, Green, and Reusable Heterogenous Catalyst for Suzuki-Miyaura Cross-coupling Reaction.

The Suzuki-Miyaura cross-coupling (SMCC) involves the coupling of organohalides and organoboron molecules in the presence of Pd(II)-based catalysts. Often SMCC reactions employ homogenous catalysts. However, such homogenous SMCC reactions are associated with certain limitations which has motivated design of effective and sustainable Pd(II)-based heterogeneous catalytic systems. Herein, we report a systematic development of a Pd(II)-immobilized and triptycene based ionic hyper crosslinked polymer (Pd@TP-iHCP) and explored its application as a heterogeneous catalyst for SMCC reaction. Pd@TP-iHCP has ample N-heterocyclic carbene (NHC) pendants that anchor Pd(II) centres on the polymeric matrix. Pd@TP-iHCP was characterized satisfactorily using FT-IR, 13 C CP-MAS NMR, BET surface area analysis, SEM, EDX and HRTEM. The performance of Pd@TP-iHCP as a heterogeneous catalyst for SMCC reactions was explored using various combinations of aryl boronic acids and aryl halides. Experimental results show that Pd@TP-iHCP is associated with a moderately high surface area. It is an efficient catalyst for SMCC (in aqueous media) with a modest loading of 0.8 mol % Pd(II)-catalyst since high yields of the expected products were obtained in shorter time intervals. Pd@TP-iHCP also features excellent stability and catalyst recyclability since it could be re-used for several cycles without any significant decrease in catalytic efficiency.

Three-dimensional sulfonic-functionalized porphyrin-based porous organic polymer for high-performance methylene blue and ciprofloxacin capture

The pollution of toxic organic dyes and unmetabolized antibiotics to environments was becoming increasingly serious, therefore, it was urgent to remove them. In this paper, a three-dimensional hypercrosslinked porphyrin-based porous organic polymer (TP-PPOPs) with 5,10,15,20-tetraphenylporphyrin and triptycene as monomers was designed and synthesized for the first time. By further reacting TP-PPOPs with chlorosulfonic acid, a new three-dimensional sulfonic acid functional material (TP-PPOPs-SO3H) with significantly improved electronegativity and hydrophilicity was obtained. Both reactions were mild and no expensive metal catalysts were required. Benefiting from the hypercrosslinked structure, stable three-dimensional rigid framework, abundant adsorption active sites and high specific surface area, TP-PPOPs-SO3H exhibited extremely fast adsorption rate, outstanding adsorption selectivity, extraordinary reusability and ultra-high adsorption capacity for MB and CIP, with the maximum adsorption capacities being 1283.33 mg·g−1 for MB and 485.39 mg·g−1 for CIP, respectively. The study of adsorption mechanism revealed that the ultra-high adsorption capacity of TP-PPOPs-SO3H on MB and CIP was mainly attributed to their strong electrostatic interaction and the extended π-conjugated frameworks and large specific surface area of TP-PPOPs-SO3H.

Preparation of phenolic hydroxyl-modified hyper-crosslinked polymers and their adsorption performance towards small molecular aromatic amines

Herein, three phenolic hydroxyl-modified hyper-crosslinked polymers were synthesized according to two-step Friedel-Crafts alkylation, and they were applied to adsorb small aromatic amines in aqueous and organic solvents. The first low-temperature Friedel-Crafts at 313 K introduced massive phenolic –OH to the intermediates, then the second high-temperature Friedel-Crafts at 353 K, also known as post-crosslinking reaction, brought a hyper-crosslinked skeleton composed of plentiful rigid methylene bridges to the target products, greatly enhancing the Brunauer-Emmett-Teller (BET) surface area (SBET) and total pore volume (Vtotal) of the polymers. In aqueous solution, the HCPS-BNAP-FDA had great potential for efficient adsorption of aniline and p-nitroaniline (p-NANL), and the Langmuir model predicted that their maximum capacities (qmax) were 209.25 mg/g and 277.30 mg/g, respectively. In cyclohexane solution, the qmax of aniline on HCPS-BNAP-FDA was predicted to be 202.38 mg/g. The removal aniline in aqueous solution could exceed 95 % when the original concentration was less than 200 mg/L, and the final concentration was 0.12 mg/L, much lower than the emission limit of China (GB 4287–2012, China). The polymer with 1,4-bis(chloromethyl)benzene (DCX) as crosslinking agent had the highest SBET (1282 m2/g) and the best adsorption performance for aniline (qmax, 258.73 mg/g). The adsorption mechanism demonstrated that the grafting of phenolic –OH groups improved the adsorption performance, as the possible hydrogen bonds and acid-base interactions. The micropores added via post-crosslinking also achieved a significant increase in adsorption capacity, that is, the pore filling adsorption mechanism.

Sulfonated hypercross-linked porous organic polymer based humidity sensor

Humidity sensors are of great significance in industry, agriculture and human activities, and many nanomaterials are already used for humidity sensing. Linear ionic polymers with hydrophilic groups have exhibited good humidity detection performance because they can adsorb water and then dissociate charged carriers. However, it suffers from the instability under high relative humidity that caused by polymer chain swelling and disengagement. To overcome this shortage, in this work, a new sensor based on hypercross-linked porous organic polymer (POP) with sulfonic acid group was fabricated to humidity detection in wide humidity range. The POP with strong covalent bonds exhibits remarkable chemical and thermal stability, and sulfonic acid group in the pore can act as fully accessible active site to enhance its ability to adsorb water. The obtained sensor shows high response (∼77) in a wide relative humidity range (11%−95% RH), short response/recovery time (9 s/21 s) and good stability. Complex impedance curves and density functional theory have been carefully investigated to understand its sensing mechanism. This work provides a new direction for the development of the impedance-type humidity sensitive materials in subsequent research and practical applications.

Synthesis of extended π‐conjugated hypercrosslinked polymers via a Friedel–Crafts reaction and an intramolecular Scholl coupling reaction

AbstractLong‐range conjugated structures are important for increasing the conductivity and broadening the application scope of hypercrosslinked polymers (HCPs). It is, however, difficult to fabricate long‐range conjugated structures using conventional HCP synthesis methods. Herein, we report a simple and efficient strategy for the synthesis of HCPs with extended π‐conjugated structures through Friedel–Crafts and intramolecular Scholl‐coupling reactions from readily available aromatic compounds under mild conditions. Two conjugated HCPs (C‐HCPs), namely, C‐HCP‐ATA and C‐HCP‐TPB, were prepared from anthracene (ATA) and triphenylbenzene (TPB), respectively, using this method. The proposed strategy not only ensures a high specific surface area of materials but also introduces a long‐range conjugated structure into HCPs. The lithium‐ion battery applications of the C‐HCPs were investigated. As anode materials, C‐HCP‐ATA and C‐HCP‐TPB displayed higher lithium storage capacities, better conductivity, and higher stability than their precursors, HCP‐ATA and HCP‐TPB, which were prepared using the conventional method.

Directly Knitted Hierarchical Porous Organometallic Polymer-Based Self-Supported Single-Site Catalyst for CO2 Hydrogenation in Water.

In recent times, heterogenization of homogeneous molecular catalysts onto various porous solid support structures has attracted significant research focus as a method for combining the advantages of both homogeneous as well as heterogeneous catalysis. The design of highly efficient, structurally robust and reusable heterogenized single-site catalysts for the CO2 hydrogenation reaction is a critical challenge that needs to be accomplished to implement a sustainable and practical CO2 -looped renewable energy cycle. This study demonstrated a heterogenized catalyst [Ir-HCP-(B/TPM)] containing a molecular Ir-abnormal N-heterocyclic carbene (Ir-aNHC) catalyst self-supported by hierarchical porous hyper-crosslinked polymer (HCP), in catalytic hydrogenation of CO2 to inorganic formate (HCO2 - ) salt that is a prospective candidate for direct formate fuel cells (DFFC). By employing this unique and first approach of utilizing a directly knitted HCP-based organometallic single-site catalyst for CO2 -to-HCO2 - in aqueous medium, extremely high activity with a single-run turnover number (TON) up to 50816 was achieved which is the highest so far considering all the heterogeneous catalysts for this reaction in water. Additionally, the catalyst featured excellent reusability furnishing a cumulative TON of 285400 in 10 cycles with just 1.6 % loss in activity per cycle. Overall, the new catalyst displayed attributes that are important for developing tangible catalysts for practical applications.

Directly Knitted Hierarchical Porous Organometallic Polymer‐Based Self‐Supported Single‐Site Catalyst for CO2 Hydrogenation in Water

AbstractIn recent times, heterogenization of homogeneous molecular catalysts onto various porous solid support structures has attracted significant research focus as a method for combining the advantages of both homogeneous as well as heterogeneous catalysis. The design of highly efficient, structurally robust and reusable heterogenized single‐site catalysts for the CO2 hydrogenation reaction is a critical challenge that needs to be accomplished to implement a sustainable and practical CO2‐looped renewable energy cycle. This study demonstrated a heterogenized catalyst [Ir‐HCP‐(B/TPM)] containing a molecular Ir‐abnormal N‐heterocyclic carbene (Ir‐aNHC) catalyst self‐supported by hierarchical porous hyper‐crosslinked polymer (HCP), in catalytic hydrogenation of CO2 to inorganic formate (HCO2−) salt that is a prospective candidate for direct formate fuel cells (DFFC). By employing this unique and first approach of utilizing a directly knitted HCP‐based organometallic single‐site catalyst for CO2‐to‐HCO2− in aqueous medium, extremely high activity with a single‐run turnover number (TON) up to 50816 was achieved which is the highest so far considering all the heterogeneous catalysts for this reaction in water. Additionally, the catalyst featured excellent reusability furnishing a cumulative TON of 285400 in 10 cycles with just 1.6 % loss in activity per cycle. Overall, the new catalyst displayed attributes that are important for developing tangible catalysts for practical applications.

Simultaneous extraction of hydroxylated polycyclic aromatic hydrocarbons and catecholamines with magnetic boronic acid hypercrosslinked polymers

Urinary hydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) and catecholamines (CAs) are important biomarkers of PAHs exposure. In this study, a novel magnetic boronic acid hypercrosslinked composite (Fe3O4@HCP-BA) is synthesized using a facile one-pot strategy and applied as a sorbent for the simultaneous extraction of OH-PAHs and CAs in urine samples. The synthesized Fe3O4@HCP-BA composites are characterized by rich pore structure, highly specific surface area, good magnetic response, and excellent selectivity and adsorption efficiency (range: 65.26–496.71 and 1227.3–1581.8 µmol g−1 for CAs and OH-PAHs, respectively). The mechanisms governing the adsorption of the OH-PAHs and CAs to the Fe3O4@HCP-BA composites were systematically studied via adsorption kinetics, isotherm models, XPS characterization, and molecular simulation. The resultant Fe3O4@HCP-BA composite-based MSPE/HPLC-FLD method exhibited good linearity (R2 > 0.9916), low limits of detection (0.2–0.3 pg mL−1 and 0.2–0.3 ng mL−1 for OH-PAHs and CAs, respectively), and good precision (intra-day and inter-day RSDs < 11.1%). The analysis of CAs and OH-PAHs in the urine samples from 14 smokers and 14 non-smokers revealed a positive correlation between the concentrations of CAs and OH-PAHs. Our findings not only establish the proposed method as a green, environmentally friendly, and simple strategy for preparing magnetic adsorbents, but also confirm it as a promising alternative method for accurate determination of OH-PAHs and CAs in biological samples.

Adsorption behaviors and mechanisms of porous hypercrosslinked polymers with adjustable functional groups toward doxycycline hydrochloride from water

AbstractImino hypercrosslinked polymers (NH‐HCPs), amino hypercrosslinked polymers (NH2‐HCPs), and carboxyl hypercrosslinked polymers (COOH‐HCPs) were synthesized through cross‐linking and Friedel‐Crafts reactions to serve as highly efficient adsorbents for doxycycline hydrochloride (DOX) in water. These polymers, NH‐HCPs, NH2‐HCPs, and COOH‐HCPs, exhibited specific surface areas measuring 450, 267.576, and 94.39 m2/g, respectively. The adsorption kinetics of DOX onto these polymers were consistent with the pseudo‐second‐order model, while the adsorption isotherms followed the Langmuir model (NH‐HCPs) and Freundlich model (NH2‐HCPs and COOH‐HCPs), respectively. The maximum DOX adsorption capacities for NH‐HCPs, NH2‐HCPs, and COOH‐HCPs were 166.82, 132.43, and 72.07 mg/g, respectively. Simulation results indicated that COOH‐HCPs exhibited the strongest adsorption capability due to a substantial presence of oxygen and nitrogen groups on its surface, enabling the formation of hydrogen bonds with DOX. However, its actual adsorption capacity was the lowest among the polymers, indicating that structural adjustments played a more significant role in improving adsorption performance compared to functional adjustments. Adsorption experiments conducted with NH‐HCPs and NH2‐HCPs further supported this hypothesis. The primary DOX adsorption mechanism of NH‐HCPs, NH2‐HCPs, and COOH‐HCPs involved the H‐bonding of oxygen and nitrogen functional groups, along with other mechanisms such as π‐π conjugated effects, pore‐filling effects, electrostatic interactions, and acid–base interactions. Overall, this study demonstrates the effectiveness of NH‐HCPs, NH2‐HCPs, and COOH‐HCPs in DOX removal from water, highlighting the significant influence of structural adjustments on adsorption performance.

Preparation of hypercrosslinked porous polymer with manifold functional groups for sensitive determination of phenylurea herbicides in beverages and celtuce samples.

Wide use of phenylurea herbicide has caused serious residue problem and threaten human health. It is important to develop viable method for their sensitive determination. Herein, a multi-functionalized porous polymer was prepared by crosslinking hexafluorobisphenol A with pyromellitic dianhydride. Using the multi-functionalized porous polymer as solid phase extraction sorbent, combined with high performance liquid chromatography, a sensitive method was established for determining phenylurea herbicides in beverages and celtuces. High sensitivity was achieved, with method detection limit (S/N=3) of 0.01---0.025ngmL-1 for beverages, 1.70ngg-1 for celtuce, and quantitation limits of 0.03---0.10ngmL-1 for beverages, 5.00ngg-1 for celtuce. The method recoveries were 80.5---120.0 % with relative standard deviations lower than 6.1%. Adsorption mechanism mainly involved F-π, F-O, π-π, polar interactions and hydrogen-bonding interactions. This study offers a simple protocol to develop multi-functional sorbents for extraction of organic pollutants.

Synthesis of magnetic hyper-crosslinked polymer from waste-expanded polystyrene as efficient sorbent for removal of Congo red and crystal violet

Given that water contaminants pose a huge threat to the environment and human health, the significance of water pollution treatments becomes increasingly evident. In the meantime, white pollution is still a huge headache to the surroundings. Herein, based upon the concept of turning trash into treasure, a series of hyper-crosslinked polymers (named as EPS-HCPs: EPS-FDA, EPS-DCX, EPS-BCMBP) were fabricated through one-step Friedel-Crafts alkylation by adopting wasted expanded polystyrene (EPS) as the raw material and taking formaldehyde dimethyl acetal (FDA), dichloroxylene (DCX) and 4,4′-bis(chloromethyl)-1,1′-biphenyl (BCMBP) as cross-linker, respectively. EPS-HCPs were applied to remove Congo red and crystal violet from aqueous solution, and the EPS-BCMBP exhibited distinctly excellent removal performance. For the convenient separation and recycling of the sorbent, the EPS-BCMBP was modified with magnetism to produce magnetic EPS-BCMBP (M-EPS-BCMBP). The maximum adsorption capacity of M-EPS-BCMBP reached 2160 mg g−1 for Congo red and 303 mg g−1 for crystal violet, with extremely fast adsorption equilibrium time (5 min). The M-EPS-BCMBP could be served as one of ideal candidates for removal of dye pollutants. This work sheds light on establishing a facile strategy for converting wasted EPS into robust sorbents for dyes removal, which plays a key part in sustainable treatment of wastewater.

A halogen-free hyper-crosslinked ionic polymer for efficient multi-conversion of CO2 into carbonates under mild conditions, with a combination of theoretical study

Designing catalysts that can efficiently convert CO2 into carbonates remains a challenge. Herein, the multifunctional CO2 affinity hyper-crosslinked ionic polymer was synthesized through self-condensation, quaternization, and ion exchange. The catalyst structure was characterized by FT-IR, TGA, NMR, XPS, and electron microscope spectra. The catalysts have a porous morphology, exhibiting a specific area of 542.2 m2/g and a CO2 adsorption capacity of 0.042 g/g. The CO2 cycloaddition with epichlorohydrin (ECH) can reach a yield of 93 % under metal- and solvent-free conditions. Meanwhile, the transesterification yield of dimethyl carbonate (DMC) between propylene carbonate (PC) and methanol was 62 % under ambient conditions and 83 % at 60 °C. Besides, the catalyst exhibited expansion of up to 16 substrates and no significant loss of activity after 6 cycles. Furthermore, the mechanism was evidenced by the combination of experimental studies and DFT-based calculations, revealing a synergistic effect between the active groups of the two reactions. This work emphasized the pathway that can simultaneously promote the formation of carbonates by both CO2 cycloaddition and transesterification under mild conditions.

Recent research progress in the synthesis, characterization and applications of hyper cross-linked polymer

Recent research progress in the synthesis, characterization and applications of hyper cross-linked polymer

A novel phosphorylated hyper-crosslinked porous polymer for efficient uranium adsorption in water

As the nuclear resource industry rapidly progresses, efficient adsorbents play a vital role in separating and eliminating uranium from aqueous solutions. Herein, 9,9-dimethyl-fluorenylphosphonic acid was designed as a phosphate functional monomer and the triptycene as a rigid backbone monomer. Through the “knitting” strategy, a novel triptycene-based phosphorylated hyper-crosslinked porous polymer (TPP-DFP) was obtained by the above monomers. The resulted polymer TPP-DFP has a high BET surface area of 1397.62 m2/g with a rich porosity. The porous polymer TPP-DFP was the first time used for uranium adsorption from water and showed outstanding adsorption performance. The maximum uranium adsorption capacity of TPP-DFP was 414.26 mg/g, which was higher than that of most of other porous adsorbents. In the presence of impurity ions such as Ca2+, Mg2+, Al3+, Co2+, Ni2+, V5+, NO3−, CO32− etc., TPP-DFP exhibited high selectivity (Su up to 99%) for uranium. In addition, TPP-DFP has excellent reusability, and the removal percentage of uranium can reach more than 95% after 5 adsorption–desorption cycles. According to the XPS experiment, the mechanism of interaction between TPP-DFP and U(VI) was mainly due to the complex formed by the phosphate functional groups and U(VI). The theory DFT calculation indicated a 1:2 ratio of U(VI) and phosphate functional group on the two-distinct graft chain, which was consistent with the experimental results. Accordingly, the “knitting” polymerization technique showed potential for preparation effective adsorbents for uranium extraction from water.