Facile self-crosslinking to improve mechanical and durability of polynorbornene for alkaline anion exchange membranes

Huang, Shengmei; He, Xiaohui; Cheng, Changwen; Zhang, Feng; Guo, Yan; Chen, Defu

doi:10.1016/j.ijhydene.2020.03.013

Cited by 29 publications

(9 citation statements)

References 64 publications

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“…As key components in all of these abovementioned applications, different kinds of alkaline anion exchange membranes (AAEMs) with rigid backbone structures, such as poly(aryl ether), poly(ether ether ketone), poly(arylene ether sulfone), polysulfone, polybenzimidazole, , polyethylene, , poly(vinylbenzyl chloride), poly(phenylene oxide), − poly(styrene- co -vinylbenzyl chloride), and fluorinated polymers, , have been reported in the literature in the past few years. A typical AAEM is composed of a polymer main chain with tethered cation ionic-exchange groups such as quaternary ammonium (QA), − imidazolium, − benzimidazolium, ,− pyridinium, ,, phosphonium, sulfonium, guanidinium, piperidinium, , pyrrolidinium, azepanium, morpholinium, and quinuclidium to facilitate the loading of free hydroxyl ions. The most reported AAEMs are based on QA cationic species pendant to a polymer main chain.…”

Section: Introductionmentioning

confidence: 99%

Cross-Linked Polybenzimidazoles as Alkaline Stable Anion Exchange Membranes

Sana

Das

Jana

2022

ACS Appl. Energy Mater.

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Despite the large volume of literature on alkaline anion exchange membranes (AAEMs), the development of efficient AAEMs with excellent alkaline stability and superior hydroxide conductivity is the major challenge. To mitigate this problem, cross-linked poly(butylated pyridinium benzimidazolium) iodide (CPBPBI) membranes were synthesized from pyridine-bridged polybenzimidazole (PyPBI) utilizing butyl iodide as the alkylating agent and 1,4-diiodobutane as a cross-linker. The AAEMs were fabricated by dipping the CPBPBI membranes in KOH to obtain CPBPBI-OH. Among the several structural variations, the CPBPBI-OBA-OH membrane displayed the highest hydroxide conductivities of 39.4 and 111 mS/cm at 30 and 80 °C, respectively. The ion exchange capacity (IEC) of CPBPBI-OH membranes was found to be altered in the range of 2.30–3.97 mequiv·g–1 at an ambient temperature depending on the polymer structure. The membranes studied in 5 M KOH solution at 80 °C for 16 days showed excellent chemical and dimensional stability. The IEC, Fourier transform infrared (FT-IR) and 1H nuclear magnetic resonance (NMR) spectra, and hydroxide ionic conductivity data of the AAEMs were compared before and after the chemical stability test, and all of these investigations proved that the membranes were highly stable in concentrated alkaline solution and almost zero or very negligible degradation was observed after harsh alkali treatment. The negligible loss of hydroxide ion conductivity of membranes even after 16 days in 5 M KOH treatment at 80 °C is attributed to the cross-linking formation that prevented the attack of OH– ions on C2 imidazolium moieties. Furthermore, the thermal and mechanical properties of the AAEMs showed excellent thermomechanical stability. Overall, the cross-linking of the PyPBI chains immensely helped in improving various physical properties, particularly hydroxide conductivity, alkaline stability, and mechanical robustness, which are important for the development of efficient AAEMs.

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Section: Introductionmentioning

confidence: 99%

Cross-Linked Polybenzimidazoles as Alkaline Stable Anion Exchange Membranes

Sana

Das

Jana

2022

ACS Appl. Energy Mater.

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“…Polymers possessing reactive groups at main chains might demonstrate self-cross-linking features. This class of polymers have attractive properties as they could be processed with the conventional processes for thermoplastics and then be in situ cross-linked to demonstrate characteristics and properties of thermosets. − In addition to good thermal properties and high mechanical strengths, some of the thermosets from the self-cross-linkable polymers show good film formability, high flexibility, and high toughness, − which are usually not observed with the conventional thermosets from small molecular monomers.…”

Section: Introductionmentioning

confidence: 99%

A Self-Protection Effect of Monomers on Preventing Gelation in Synthesis of Main-Chain Polybenzoxazines with High Molecular Weights

Huang

Liu

2021

Macromolecules

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Self-cross-linkable main-chain polybenzoxazines (PBz) could be directly obtained with polymerization of a diamine, a bisphenol compound, and formaldehyde. Two major concerns of preparation of main-chain PBz are gelation in the polymerization system and low molecular weight of the PBz products. In this work, an effective approach to address the issues has been demonstrated with employing a Meldrum’s acid-containing diamine (MADA) as a functional monomer. MADA could retard the trimerization of methylol groups and formation of cyclic triazines in the polymerization system through the interaction between MA and methylol groups, so as to prevent gelation occurring in the polymerization system. With the self-protection of the diamine monomers, adjustments of the used solvents have been done to prevent PBz precipitation from the polymerization solution in the duration of reaction and consequently to result in an increase in the molecular weights of the prepared PBz (MW: 12500 Da; inherent viscosity: 0.39 dL g–1). Moreover, the MA groups provide additional cross-linking sites to the PBz chains, so as to increase the cross-linking density and enhance the thermal and mechanical properties of the corresponding cross-linked PBz. The MADA-based cross-linked PBz shows good film formability, film flexibility with a near-180° bending, a high glass transition temperature (350 °C), and a Young’s modulus of 2.26 GPa. The values are superior over the data (T g: 267 °C; Young’s modulus: 1.74 GPa) found with the conventional 4,4′-oxydianiline-based cross-linked PBz. Significant advances on both PBz synthesis and cross-linked PBz properties have been demonstrated.

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“…In comparison with the linear polymers, AEMs with crosslinked structures exhibited controlled water uptake and swelling, as well as improved dimensional stability. 29,62 Li et al prepared a series of FG1 functionalized AEMs with a thermally cross-linkable azide group, and then the membranes were crosslinked by thermal crosslinking at 135 C for 18 h. 45 It was found that the thermal crosslinked membrane exhibited extremely low water uptake but comparable hydroxide conductivity, which may be attributed to the "side-chain" structure of cations. More importantly, these crosslinked membranes can reduce the attack of hydroxide ions or water, and thereby improving the alkaline stability (maintained over 65% of initial conductivity in 5 M or 10 M NaOH at 80 C for 400 h).…”

Section: Ppo-based Crosslinked Aems Via Cuaacmentioning

confidence: 99%

“…24 Until now, a variety of commercial and synthetic polymers have been used as the backbone of AEMs, such as poly(vinylbenzyl chloride) (PVC), polybenzimidazole (PBI), poly(phenylene oxide) (PPO), polyvinyl alcohol (PVA), poly(ether sulfone) (PES), poly(arylene ether nitrile) (PAEN), polystyrene (PS), and so on. 27 Generally, positive-charged groups, such as quaternary ammonium (QA), 28 imidazolium, 29 metal cations, 30 N-spirocyclic ammonium, 31 guanidinium, phenyltrimethylammonium, 32 piperidinium, 33 phosphonium, 34 and pyrrolidinium 35 have been introduced to AEMs by connecting to the polymer backbone through covalent bonds. 36 As the most commonly used organic cation, QA may degrade under alkaline conditions via the following pathways 37 : (i) Hofmann elimination, the β-H of QA groups is attacked by OH À and results in the degradation of QA group into olefins and tertiary amines; (ii) nucleophilic substitution (S N 2), the α-C of QA group is attacked by OH À and results in the degradation of QA group into tertiary amines and H 2 O; (iii) ylide formation, when none of the four groups on the quaternary nitrogen bears a β-H, the nucleophilic substitution that yields an alcohol is the only possible reaction.…”

Section: Introductionmentioning

confidence: 99%

Advance of click chemistry in anion exchange membranes for energy application

Yang

Chen

Yan

et al. 2022

Journal of Polymer Science

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Click chemistry has attracted tremendous attention in polymer synthesis due to its high efficiency, considerable yield, and simple synthesis/work-up procedures. Among the various functional polymer materials prepared by click chemistry, anion exchange membrane (AEM) is a kind of polyelectrolyte which contains cations attached to the polymer skeleton. Click chemistry not only provides facile pathways for the preparation of AEMs but also generates diverse architectures of AEMs with robust performance. The commonly used click chemistry in AEMs consists of: (i) Diels-Alder reaction, (ii) thiol-ene, and (iii) Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC). This review will focus on the advance of click chemistry in the preparation of AEMs, especially synthetic approaches for different AEMs and their corresponding application in energy-related fields, such as fuel cells, redox flow battery, electrodialysis, and so on.

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Facile self-crosslinking to improve mechanical and durability of polynorbornene for alkaline anion exchange membranes

Cited by 29 publications

References 64 publications

Cross-Linked Polybenzimidazoles as Alkaline Stable Anion Exchange Membranes

Cross-Linked Polybenzimidazoles as Alkaline Stable Anion Exchange Membranes

A Self-Protection Effect of Monomers on Preventing Gelation in Synthesis of Main-Chain Polybenzoxazines with High Molecular Weights

Advance of click chemistry in anion exchange membranes for energy application

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