Friedel-Crafts Polymerization Research Articles

Experimental and theoretical investigation of phenylpyridine-based hypercrosslinked polymers for atmospheric CO2 adsorption and fixation under solvent-/metal-free conditions

Several phenylpyridine- and phenyl-based hypercrosslinked polymers (HCPs) were prepared via a one-step Friedel-Crafts polymerization and used as catalysts for the cycloaddition reaction between atmospheric CO2 and epoxides to produce cyclic carbonates. The structural characteristics and catalytic activity of different HCP catalysts were compared, while the recycling performance and universality to various substituted epoxides were investigated. The as-prepared catalysts exhibited regular pore structure and high specific surface area (1133 m2/g). Under the synergistic effect of tetrabutylammonium iodide (TBAI), the optimized TPA-HCP-Py efficiently converted atmospheric CO2 into cyclic carbonates with good to excellent product yields. Furthermore, the TPA-HCP-Py catalyst was easy to recover, and no significant changes were observed after reusing for five times, which demonstrated its excellent recycling performance. The interactions between different active sites and reactants in the TPA-HCP-Py/TBAI catalytic system were investigated by DFT calculation, revealing the catalytic reaction mechanism and providing valuable guidance for developing new multifunctional catalysts.

Acid doped branched poly(biphenyl pyridine) membranes for high temperature proton exchange membrane fuel cells and vanadium redox flow batteries

Both high temperature proton exchange membrane fuel cell (HT-PEMFC) and vanadium redox flow battery (VRFB) are represented as two advanced energy conversion and energy storage devices. They have a same core component of the separator membrane, which still faces several intractable scientific and industrial issues. For HT-PEMFC, the increase in conductivity is normally as the expense of mechanical strength; while for VRFB, the improvement in proton transport always brings in serious vanadium ion crossover. Meanwhile, the membrane also should possess an excellent chemical stability towards the attack by radicals or high valence vanadium ions. The above questions can be well solved by the preparation of triphenylbenzene (TPB) branched poly(biphenyl-4-acetylpyridine) membranes (x%TPB-PBAP), which are synthesized by one-step Friedel-Crafts polymerization. Amounts of alkaline pyridine groups equip x%TPB-PBAP membranes with good phosphoric acid and sulfonic acid absorption capability, resulting in high proton conductivity in both HT-PEMFC and VRFB. Meanwhile, the construction of the branched structure, i.e. a kind of covalently crosslinked network, can improve the mechanical strength and chemical stability. Consequently, the 1.5 %TPB-PBAP membrane displays large potential in both HT-PEMFC and VRFB. A single H2-O2 cell based on the 1.5 %TPB-PBAP/263 %PA membrane shows a peak power density of 1010 mW cm−2 at 180 °C without any back pressure. Meanwhile, the VRFB based on above membrane also depicts better battery efficiencies and cycle durability than that with Nafion 212.

Stable Anion Exchange Membrane Bearing Quinuclidinium for High‐performance Water Electrolysis

AbstractAnion exchange membranes (AEMs) are core components in anion exchange membrane water electrolyzers (AEM‐WEs). However, the stability of functional quaternary ammonium cations, especially under high temperatures and harsh alkaline conditions, seriously affects their performance and durability. Herein, we synthesized a 1‐methyl‐3,3‐diphenylquinuclidinium molecular building unit. Density functional theory (DFT) calculations and accelerated aging analysis indicated that the quinine ring structure was exceedingly stable, and the SN2 degradation mechanism dominated. Through acid‐catalyzed Friedel–Crafts polymerization, a series of branched poly(aryl‐quinuclidinium) (PAQ‐x) AEMs with controllable molecular weight and adjustable ion exchange capacity (IEC) were prepared. The stable quinine structure in PAQ‐x was verified and retained in the ex situ alkaline stability. Furthermore, the branched polymer structure reduces the swelling rate and water uptake to achieve a tradeoff between dimensional stability and ionic conductivity, significantly improving the membrane's overall performance. Importantly, PAQ‐5 was used in non‐noble metal‐based AEM‐WE, achieving a high current density of 8 A cm−2 at 2 V and excellent stability over 2446 h in a gradient constant current test. Based on the excellent alkaline stability of this diaryl‐quinuclidinium group, it can be further considered as a multifunctional building unit to create multi‐topological polymers for energy conversion devices used in alkaline environments.

Stable Anion Exchange Membrane Bearing Quinuclidinium for High-performance Water Electrolysis.

Anion exchange membranes (AEMs) are core components in anion exchange membrane water electrolyzers (AEM-WEs). However, the stability of functional quaternary ammonium cations, especially under high temperatures and harsh alkaline conditions, seriously affects their performance and durability. Herein, we synthesized a 1-methyl-3,3-diphenylquinuclidinium molecular building unit. Density functional theory (DFT) calculations and accelerated aging analysis indicated that the quinine ring structure was exceedingly stable, and the SN2 degradation mechanism dominated. Through acid-catalyzed Friedel-Crafts polymerization, a series of branched poly(aryl-quinuclidinium) (PAQ-x) AEMs with controllable molecular weight and adjustable ion exchange capacity (IEC) were prepared. The stable quinine structure in PAQ-x was verified and retained in the ex situ alkaline stability. Furthermore, the branched polymer structure reduces the swelling rate and water uptake to achieve a tradeoff between dimensional stability and ionic conductivity, significantly improving the membrane's overall performance. Importantly, PAQ-5 was used in non-noble metal-based AEM-WE, achieving a high current density of 8 A cm-2 at 2 V and excellent stability over 2446 h in a gradient constant current test. Based on the excellent alkaline stability of this diaryl-quinuclidinium group, it can be further considered as a multifunctional building unit to create multi-topological polymers for energy conversion devices used in alkaline environments.

Tripodal receptor cross-linked polymer as a promising adsorbent for iodine vapor capture and adsorption from water

A cross-linked tripodal receptor polymer was synthesized using a Friedel-Crafts polymerization reaction which showed an iodine vapor capture capacity of 2.47 g g−1 at 80 °C with remarkable iodine adsorption per unit BET surface area of 86 wt/(m2/g). UV–Vis spectral analysis confirmed that the polymer adsorbent rapidly adsorbs iodine from water. Importantly, the polymer exhibited reversible iodine adsorption allowing the polymer to be reused several times without losing the adsorption efficiency. We also investigated the adsorption capability of the synthesized polymer TPP as a filtration material for practical applications. Through dynamic adsorption experiments using a syringe pump setup, we demonstrated that a mere 40 mg of the TPP polymer effectively purifies 20 ml of a 2.5 mM aqueous iodine solution. Our findings underscore the exceptional adsorption efficiency of the TPP polymer, as evidenced by the successful removal of iodine molecules from the solution. These results not only highlight the potential of the TPP polymer for its utility in environmental remediation applications particularly for the treatment of effluents from nuclear reactors.

Semi-fluorinated (6F) polyaryl ethers and polyphenylenes via interfacial electrophilic condensation polymerization with hexafluoroacetone hydrate

A series of semi-fluorinated polymers were obtained by Friedel-Crafts polymerization of hexafluoroacetone trihydrate (HFAH) with a variety of activated and non-activated aromatic monomers. Interfacial (water/dichloroethane) electrophilic aromatic substitution (EAS) polymerizations were carried out with trifluoromethanesulfonic anhydride (Tf2O) and Aliquat® 336 as phase transfer catalyst. This versatile and straightforward method achieved the synthesis of moderate to high molecular weight (12.0–29.6 kDa) polyaryl ethers and polyphenylenes with 1,1,1,3,3,3-hexafluoroisopropylene (6F) main chain linkages. Predominantly amorphous film-forming materials were obtained with low branching, high solubilities in common organic solvents, thermo-oxidative stabilities up to 500 °C, and glass transitions (Tg) ranging from 157 to 250 °C. The optical and dielectric properties of these materials were also studied from which high visible region transmittance and low dielectric constant values comparable with commercial materials were found.

Low water swelling polyaromatic proton exchange membranes

A carbon-carbon linked polyaromatic electrolyte was designed and synthesized for proton exchange membranes. The facile synthesis consists of a metal-free Friedel-Crafts polymerization and a direct post-sulfonation. To prevent the random sulfonation, the trifluorobuanone monomer was incorporated as a spacer to sterically confine the sulfonated area. Hydrophobic/hydrophilic separation was observed in the polymer's microstructure. The membrane (ion exchange capacity = 1.88 mmolg−1) displayed low water swelling (area swelling = 38.0% at 80 °C) at a slightly higher proton conductivity than Nafion 212. Tensile strength of 39.3 MPa and elongation at break of 67.0% were confirmed by stress-strain measurements. The membrane electrode assembly afforded an electrolyzing performance of 4.6 A cm−2@2.0 V while Nafion 212 was 3.6 A cm−2@2.0 V under the same testing conditions. The 45 μm film exhibited better stability than Nafion 212 (∼50 μm) both in the preliminary in-situ cyclic accelerated stress test and the 800-h galvanostatic evaluation. The degradation rate of our thin membrane in the 800-h test was comparable to that of Nafion 115 (∼125 μm).

Synthesis of novel phosphate-based hypercrosslinked polymers for efficient uranium extraction from radioactive wastewater

The uranium extraction from radioactive wastewater is vitally important for both the sustainable nuclear energy and environmental protection. However, the efficient extraction of uranium (VI) faces great challenges due to the complex compositions of radioactive wastewater. In this work, phosphate-based hypercrosslinked polymer (HCP) is designed and synthesized via the Friedel-Crafts polymerization of different aryl phosphate with crosslinking monomer for efficient uranium (VI) extraction. The HCP has uranophilic phosphate group, large specific surface area and mesoporous structure. It can effectively adsorb uranium (VI) from solution under various pH conditions and the adsorption efficiency can achieve 98 %. The maximum sorption capacity of HCP reaches 302 mg/g at pH 7.0 with a sorbent dosage of 0.33 g/L, which is higher than many other phosphate-based polymer. Meantime, it shows good sorption selectivity for uranium (VI) over many other coexisting metal ions. It shows recyclability and can be well applied to the fixed-bed sorption column for long-time uranium (VI) extraction. Investigations on sorption mechanism reveals that the coordination effect between phosphate groups and uranium (VI) ions enhances the effective sorption of uranium (VI) on HCP. This work provides a facile way to construct heterogeneous phosphate sorbents, and demonstrates their potential for practical application in uranium (VI) recovery from radioactive wastewater.

Effect of POSS Size on the Porosity and Adsorption Performance of Hybrid Porous Polymers

Polyhedral oligomeric silsesquioxanes (POSS), with unique cage-like three-dimensional (3D) structures, have been considered as promising nanoblocks for novel hybrid porous polymers (HPPs). To date, T8 POSS-based HPPs have been extensively studied, while the potential of larger POSS remains elusive and intriguing. Herein, we report the synthesis of a series of T8, T10, and T12 POSS-based HPPs (T8TPM, T10TPM, and T12TPM) and investigate their size-dictated structure–property relationships. These novel HPPs with identical composition yet distinct framework topologies are available through Friedel–Crafts polymerization of octa-, deca-, and dodeca-vinyl POSS with triptycene in a fixed mass ratio. It is found that the structures and properties of these materials are highly related to the POSS type and, more importantly, display an almost linear increase with increasing POSS size. Specifically, the surface area, pore volume, and adsorption capacity of T12TPM are 1214.8 m2 g–1, 1.00 cm3 g–1, and 4462.4 mg g–1 (Rhodamine B), showing an increase of 13.2, 56.3, and 37.9% compared with T8TPM, respectively. These results demonstrate the profound influence of the POSS size on the structure–property relationship of HPPs and could be used to predict the property of larger T14, T16, and T18 POSS-based HPPs. This calls for future endeavors in the exploration of larger POSS-based HPPs.

Rationalizing the formation of porosity in mechanochemically-synthesized polymers.

In this study, we present a matrix of 144 mechanochemically-synthesized polymers. All polymers were constructed by the solvent-free Friedel-Crafts polymerization approach, employing 16 aryl-containing monomers and 9 halide-containing linkers, which were processed in a high-speed ball mill. This Polymer Matrix was utilized to investigate the origin of porosity in Friedel-Crafts polymerizations in detail. By examining the physical state, molecular size, geometry, flexibility, and electronic structure of the utilized monomers and linkers, we identified the most important factors influencing the formation of porous polymers. We analyzed the significance of these factors for both monomers and linkers based on the yield and specific surface area of the generated polymers. Our in-depth evaluation serves as a benchmark study for future targeted design of porous polymers by the facile and sustainable concept of mechanochemistry.

Pillar[5]arene-based cross-linked polymer for the rapid adsorption of iodine from water and vapor phases

Pillar[5]arene-based cross-linked microporous polymer ( P[5]A-MPP ) was synthesized via Friedel-crafts polymerization reaction. P[5]A-MPP exhibited high iodine vapor capture capability (3.84 g g −1 ) at 80 °C. Detailed UV–vis spectroscopic analysis revealed the rapid removal of iodine from water. This work highlights the efficient iodine adsorption efficiency in vapor phase, as well as rapid removal of iodine from aqueous solution and the recyclability of pillar[5]arene-based 3D cross-linked microporous polymer. Pillar[5]arene macrocycle-based cross-linked polymer was synthesized and used for iodine adsorption to capture iodine both in vapour phase as well as aqueous solution. The pillar[5]arene based polymer adsorbent showed remarkable recyclability at least five times without losing the efficiency. • Pillar[5]arene-based polymer ( P[5]A-MPP ) is a potential material for the removal of iodine from water. • P[5]A-MPP capture iodine in vapor phase with an iodine uptake capacity of 3.84 g/g. • P[5]A-MPP displayed excellent iodine adsorption capability per unit SBET of 13.6 wt/(m 2 /g). • P[5]A-MPP can remove >83% of iodine during the initial 15 min upon shaking. • P[5]A-MPP showed remarkable recyclability at least five times without losing efficiency.

Hyper-crosslinked dicationic ionic liquid porous polymers for nitrophenol adsorption

In this work, an imidazolyl dicationic ionic liquid was employed as a monomer to construct a novel nitrogen-rich hyper-crosslinked polymer (HCP–N) for the separation of 4-nitrophenol (4-NP) from wastewater. HCP-N was fabricated through a facile one-pot Friedel-Crafts polymerization, using p-dichloroxylene as cross-linking agents, as well as pore structure regulators. The synthesized HCP-N were randomly stacked by lamellar blocks aggregated by nanospheres. The adsorption kinetic data complied well with pseudo-second-order rate equation while the adsorption isothermal equilibriums conformed to the Freundlich model. At the initial concentration of 1000 mg L−1, the adsorption capacity for 4-NP was up to 437 mg g−1. The influence of acidity, temperature and coexisted metal ions were investigated systematically. Coexisted Pb2+ at low concentration (<150 mg L−1) could significantly increase the adsorption capacity of HCP-N through complexing-bridging mechanism. The mechanism analyses revealed that hydrogen bonding, electrostatic and π−π interaction contributed together to the adsorption of 4-NP on HCP-N. The adsorbent could be recycled at least five times after the adsorbed 4-NP was separated by ethyl acetate extraction.

Friedel–Crafts Polymerization Approach to Easily Recyclable Heterogeneous Chiral Phosphoric Acids

Key words organophosphoric acids - Friedel–Crafts reaction - polymerization - transfer hydrogenation

Poly(arylene pyridine)s: New alternative materials for high temperature polymer electrolyte fuel cells

Developing high-performance and low-cost high temperature polymer exchange membranes (HT-PEMs) is a huge challenge to fuel cells. Here, two poly(arylene pyridine)s (PTAP and PBAP) are synthesized through a simple one-step Friedel–Crafts polymerization of 4-acetylpyridine and para-terphenyl/biphenyl. Both PTAP and PBAP exhibit superior organic solubility and excellent thermal stability. Owing to pyridine groups, PBAP and PTAP membranes display excellent phosphoric acid (PA) absorption capability. The PTAP membrane achieves a PA uptake of 220% after immersing in 85 wt% PA solution at 100 °C, and a high conductivity of 0.102 S cm−1 at 180 °C. Specially, PBAP and PTAP also possess remarkable chemical stability. After 450 h Fenton test, the PTAP membrane still exhibits a high PA uptake of 200% and high conductivity of 0.086 S cm−1. A single H2-O2 cell based on the PTAP/220% membrane shows a peak power density of 743 mW cm−2 at 180 °C without any back pressure, which also displays excellent durability under 200 mA cm−2 and 400 mA cm−2 at 160 °C. Thus, this work develops a facile, cost effective and up-scalable synthetic route of alternative HT-PEM under mild conditions, comparing with the state-of-the-art polybenzimidazole (PBI) membrane.

Ladder polymers of intrinsic microporosity from superacid-catalyzed Friedel-Crafts polymerization for membrane gas separation

Polymers of intrinsic microporosity have attracted comprehensive attention in membrane-mediated gas separation because of their rigid and contorted structure that facilitates well-defined microporosity for fast and selective gas transport. We report a new macromolecular design synthesizes semi-ladder and fully-ladder polymers of intrinsic microporosity containing 9H -xanthene units by superacid-catalyzed Friedel-Crafts polymerization named SACPs. The prepared SACP membranes display high microporosity with amorphous chain packing structure, high FFV, and high BET surfaces areas. In particular, SACP-3 exhibited the most elevated BET surfaces area of 568 m 2 /g, fractional free volume (FFV) of 0.243, and bimodal micropore size distribution with two maxima at ∼5 and ∼8 Å, respectively. Due to its fully ladder architecture, SACP-3 exhibits highly permeable gas transport with CO 2 permeability of 6497 Barrer and CO 2 /CH 4 selectivity of 7.8, respectively. The microporosity and gas permeation properties of SACP membranes are also demonstrated to be highly tailorable by employing different monomers. The facile polymerization procedure, excellent solubility and processability, highly diverse tunability, and outstanding gas separation performance render SACP membranes attractive for many membrane-mediated gas separation processes. • A new spirobisindane-based fully-ladder polymer of intrinsic microporosity is synthesized with high BET surface area and FFV. • Superacid-catalyzed ladder polymer of intrinsic microporosity displays a bimodal micropore size distribution. • Rigid ladder polymer shows superior plasticization resistance than less microporous semi-ladder polymer.

Rosin-based porous heterogeneous catalyst functionalized with hydroxyl groups and triazole groups for CO2 chemical conversion under atmospheric pressure condition

Development of efficient, green and recyclable heterogeneous catalysts for the chemical conversion of CO2 into cyclic carbonates with excellent yields under atmospheric pressure condition is still a very challenging task. Herein, a class of biomass-derived hyper-cross-linked porous heterogeneous catalysts MPAc-Br and MPAc-OH-Br, based on easily available and sustainable rosin, was synthesized by Friedel–Crafts polymerization and the further N-alkylation of triazole groups. Compared with MPAc-Br, the bifunctional catalyst MPAc-OH-Br (bearing triazole IL groups and -OH groups) exhibited higher catalytic activity for direct chemical conversion of CO2 into cyclic carbonates (up to 99% yields) under metal-, solvent-free and atmospheric pressure conditions. The rosin-based porous molecular structure and bifunctional groups on the surface of MPAc-OH-Br played a very important role in the promoting the cycloaddition of CO2 with epoxides under the optimal conditions. Furthermore, MPAc-OH-Br exhibited good stability and reusability (96% yield after 10 recycles).

High chemical stability anion exchange membrane based on poly(aryl piperidinium): Effect of monomer configuration on membrane properties

In recent years, ether-free polyaryl polymers prepared by superacid-catalyzed Friedel-Crafts polymerization have attracted great research interest in the development of anion exchange membranes(AEMs) due to their high alkali resistance and simple synthesis methods. However, the selection of monomers for high-performance polymer backbone and the relationship between polymer structure construction and properties need further investigated. Herein, a series of free-ether poly(aryl piperidinium) (PAP) with different polymer backbone steric construction were synthesized as stable anion exchange membranes. Meta-terphenyl, p-terphenyl and diphenyl-terphenyl copolymer were chosen as monomers to regulate the spatial arrangement of the polymer backbone, which tethered with stable piperidinium cation to improve the chemical stability. In addition, a multi-cation crosslinking strategy has been applied to improve ion conductivity and mechanical stability of AEMs, and further compared with the performance of uncrosslinked AEMs. The properties of the resulting AEMs were investigated and correlated with their polymer structure. In particular, m-terphenyl based AEMs exhibited better dimensional stability and the highest hydroxide conductivity of 144.2 mS/cm at 80 °C than other membranes, which can be attributed to their advantages of polymer backbone arrangement. Furthermore, the hydroxide conductivity of the prepared AEMs remains 80%–90% after treated by 2 M NaOH for 1600 h, exhibiting excellent alkaline stability. The single cell test of m-PTP-20Q4 exhibits a maximum power density of 239 mW/cm2 at 80 °C. Hence, the results may guide the selection of polymer monomers to improve performance and alkaline durability for anion exchange membranes.

Tunable construction of biphenyl-based porous polymeric nanostructures and their synergistically enhanced performance in pollutant adsorption and energy storage

Morphological diversity and porosity of porous organic polymers (POPs) exert vital influence on their potential applications. Herein, we demonstrate the morphology and porosity design of biphenyl-based hyper-cross-linked porous organic polymers by using a Lewis acid catalyzed Friedel–Crafts polymerization in the presence of formaldehyde dimethyl acetal (FDA) as cross-linker. The chemical composition of POPs is tunable by simply varying monomer to FDA ratio, leading to considerable morphological diversity such as the nanospheres, nanofibers, and flower-like nanostructures. High specific surface areas with mostly microporous nature, stable organic frameworks and tunable morphologies coupled with facile synthetic protocol let the hyper-cross-linked polybiphenyl (HCPbPh) based POPs exhibit the outstanding adsorption capacity and efficiency towards p-cresol based pollutant. The obtained carbon materials by direct pyrolysis of corresponding POPs can be used as the electrode materials for supercapacitors, exhibiting outstanding electrochemical performance with specific capacitance up to 421 F g−1 at 1 A g−1, and capacitance retention of 97% even after 10,000 cycles at 12 A g−1. This methodology delivers a new platform for the fabrication of microporous and mesoporous materials for various potential applications including energy storage, adsorption, and catalysis.

Photocatalytic Suzuki–Miyaura Coupling Reactions over Palladium Anchored on 8‐Hydroxyquinoline‐Based Polymers

AbstractThrough a one‐pot Friedel–Crafts polymerization method, a series of 8‐hydroxyquinoline‐based polymers with excellent light capturing ability is synthesized to support palladium for light‐driven Suzuki–Miyaura reactions (SMRs). The results of X‐ray powder diffractometer and transmission electron microscopy analyses suggest that the 8‐hydroxyquinoline‐based polymers are amorphous in structure and irregular in morphology. According to the data of thermogravimetric analysis and Brunauer‐Emmett‐Teller gas absorption, they are thermally stable up to 340 °C and are large in specific surface area. With palladium anchored securely on the 8‐hydroxyquinoline units of the polymer skeleton, the obtained photocatalysts exhibit excellent activity and reusability in SMRs under blue‐light irradiation.

Synthesis of secondary amine‐based fluorescent porous organic polymers via Friedel–Crafts polymerization reaction for adsorbing and fluorescent sensing iodine

AbstractWe present the preparation and characterization of a novel class of secondary amine‐based porous organic polymers (POPs: TDPA and TTPBTA), and their iodine adsorption, fluorescence sensing properties for the first time. Two secondary amine‐based POPs were synthetized by Friedel−Crafts polymerization reaction catalyzed via methylsulfonic acid with yields of 22.51 and 54.44%. The thermal stability of resulting POPs run up to above 268 and 568°C, and their BET specific surface areas are 56.5 and 2.49 m2 g−1, respectively. Their iodine adsorption and fluorescent sensing properties are comparable to that of triphenylamine (TPA)‐based (tertiary amine) POPs. The resulting POPs display excellent sorption abilities to iodine molecules with the iodine adsorption capacity of about 3.93 and 1.64 g g−1. Adsorbed iodine is easily desorbed by heating or washing with organic solvents, which make them reusable. They can also adsorb iodine from cyclohexane solution. Moreover, the POPs possess excellent fluorescent sensing property for I2 with Ksv of 1.85 × 104 and 6.56 × 104 L mol−1, as well as the limits of detection (LODs) of 1.62 × 10−11 and 6.86 × 10−12 mol L−1. The performance of adsorbing and fluorescence sensing iodine can be explained by electron transfer mechanism.