Study on the alkaline stability of imidazolium and benzimidazolium based polyelectrolytes for anion exchange membrane fuel cells

Jheng, Li‐Cheng; Tai, Chin Kuen; Hsu, Steve Lien Chung; Lin, Bi Yun; Chen, Likey; Wang, Bo Cheng; Chiang, Lieh Kuang; Ko, Wen Ching

doi:10.1016/j.ijhydene.2016.11.129

Cited by 41 publications

(20 citation statements)

References 30 publications

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“…Figure 3a presented the TGA curves of the PBI, PBI-DIm, and PBI-DIm-Si hybrid membranes recorded from 100 °C to 800 °C. As expected, the weight loss in the Compared with PBI polymer backbone, imidazolium cations are relatively unstable and possible to undergo thermal degradation when the temperature exceeds 250 • C [47,48]. Figure 3a presented the TGA curves of the PBI, PBI-DIm, and PBI-DIm-Si hybrid membranes recorded from 100 • C to 800 • C. As expected, the weight loss in the temperature range approximately between 250 • C and 400 • C due to the decomposition of dimethylimidazolium side chains was detected for PBI-DIm and PBI-DIm-Si hybrid.…”

Section: Synthesis and Characterizationsupporting

confidence: 67%

“…This finding indicated that the hydrolysis and condensation occurred during the sol-gel process. Compared with PBI polymer backbone, imidazolium cations are relatively unstable and possible to undergo thermal degradation when the temperature exceeds 250 °C [47,48]. Figure 3a presented the TGA curves of the PBI, PBI-DIm, and PBI-DIm-Si hybrid membranes recorded from 100 °C to 800 °C.…”

Section: Synthesis and Characterizationmentioning

confidence: 99%

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Dimethylimidazolium-Functionalized Polybenzimidazole and Its Organic–Inorganic Hybrid Membranes for Anion Exchange Membrane Fuel Cells

Jheng

Cheng

et al. 2021

Polymers

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A quaternized polybenzimidazole (PBI) membrane was synthesized by grafting a dimethylimidazolium end-capped side chain onto PBI. The organic–inorganic hybrid membrane of the quaternized PBI was prepared via a silane-induced crosslinking process with triethoxysilylpropyl dimethylimidazolium chloride. The chemical structure and membrane morphology were characterized using NMR, FTIR, TGA, SEM, EDX, AFM, SAXS, and XPS techniques. Compared with the pristine membrane of dimethylimidazolium-functionalized PBI, its hybrid membrane exhibited a lower swelling ratio, higher mechanical strength, and better oxidative stability. However, the morphology of hydrophilic/hydrophobic phase separation, which facilitates the ion transport along hydrophilic channels, only successfully developed in the pristine membrane. As a result, the hydroxide conductivity of the pristine membrane (5.02 × 10−2 S cm−1 at 80 °C) was measured higher than that of the hybrid membrane (2.22 × 10−2 S cm−1 at 80 °C). The hydroxide conductivity and tensile results suggested that both membranes had good alkaline stability in 2M KOH solution at 80 °C. Furthermore, the maximum power densities of the pristine and hybrid membranes of dimethylimidazolium-functionalized PBI reached 241 mW cm−2 and 152 mW cm−2 at 60 °C, respectively. The fuel cell performance result demonstrates that these two membranes are promising as AEMs for fuel cell applications.

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Section: Synthesis and Characterizationsupporting

confidence: 67%

Section: Synthesis and Characterizationmentioning

confidence: 99%

Dimethylimidazolium-Functionalized Polybenzimidazole and Its Organic–Inorganic Hybrid Membranes for Anion Exchange Membrane Fuel Cells

Jheng

Cheng

et al. 2021

Polymers

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“…A strong resonance signal at d near 1.264-1.245 ppm is obtained due to the cumulative influence of (-CH 2 -) n groups attached on the side to the terminal methyl groups (g). The two new signals found at around d value 3.9 ppm (a) and d value 4.1 ppm (e) are assigned to the methyl protons attached to the nitrogen of imidazolium [29]. The signals corresponding to the other methine protons of imidazolium side groups are found to appear at d = 7.371-8.884 ppm (b, c, d).…”

Section: Spectroscopic Characterization Of Ionic Liquidsmentioning

confidence: 92%

Synthesis, Characterization, Surface Properties and Micellization Behaviour of Imidazolium‐based Ionic Liquids

Pillai

Pal

2017

J Surfact & Detergents

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Ionic liquids (IL) have emerged as a prospective new material for a wide range of industrial applications, owing to their unique structures and properties. Hence, understanding the structure–property relationships of IL is very important for both fundamental and industrial applications. In this study, a series of imidazolium‐based IL with different chain lengths, namely C8mimBF4, C10mimBF4 and C12mimBF4, were synthesized. Their molecular structures were confirmed by proton nuclear magnetic resonance (1H NMR) and Fourier transform infrared (FTIR) analysis. Thermal gravimetric analysis (TGA) revealed that the IL synthesized were thermally stable in the desired temperature range. Dynamic light scattering (DLS) results of IL was analyzed in order to understand the effect of alkyl length on micellar size. Conductivity and surface tension measurements were carried out to determine the adsorption and aggregation characteristics in aqueous solutions. The influences of temperature as well as alkyl chain length on viscosity were also investigated. Surface adsorption parameters such as surface excess, minimum area, effectiveness and efficiency were also determined from equilibrium surface tension data. A careful analysis of the thermodynamic aspects of air‐ionic liquid aqueous systems reveals that free energies of adsorption are favoured over micellization for all systems.

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“…Most published works analysed degradation of AEMs by measuring weight change, ion exchange capacity (IEC), and ionic conductivity loss. The use of density functional theory (DFT) and first‐principles calculations have been explored rapidly, in order to measure the energies involved in the degradation reactions and determine the alkaline stability of different AEM chemistries such as imidazolium, guanidinium, tetraalkylammonium, and BTMA tethered functionalities.…”

Section: Introductionmentioning

confidence: 99%

Density functional theory study on the degradation of fuel cell anion exchange membranes via removal of vinylbenzyl quaternary ammonium head group

Espiritu

Tan

Lim

et al. 2020

J of Physical Organic Chem

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The alkaline stability of different tethered amine functional groups of fuel cell anion exchange membranes (AEMs), namely, trimethyl amine (TMA), 1‐azabicyclo[2.2.2]octane (ABCO), 1,4‐diazabicyclo[2.2.2]octane (DABCO), and N‐methylpiperidine (NMP), is investigated using density functional theory (DFT). Among the amine functional groups investigated, ABCO emerged as the most stable exhibiting the highest energy of barrier (EOB) of 33.5 kcal/mol, while DABCO has the lowest EOB of 30.0 kcal/mol due to the presence of an additional electron‐withdrawing nitrogen. The calculated lowest unoccupied molecular orbital (LUMO) energy revealed the trend of increasing alkaline stability against nucleophilic attack, consistent with their measured barrier energies: DABCO < TMA < NMP < ABCO. Most importantly, the DFT calculations confirmed the proposed multistep AEM degradation mechanism via the detachment of the whole vinylbenzyl quaternary ammonium group through the following steps: (1) nucleophilic attack leading to the loss of aromaticity with subsequent transformation to a quinodimethane moiety, (2) detachment of the quinodimethane‐like intermediate from the polymer backbone by the attack of superoxide and/or peroxy radicals via oxidative cleavage, and (3) the rearomatisation of the reaction intermediate.

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Study on the alkaline stability of imidazolium and benzimidazolium based polyelectrolytes for anion exchange membrane fuel cells

Cited by 41 publications

References 30 publications

Dimethylimidazolium-Functionalized Polybenzimidazole and Its Organic–Inorganic Hybrid Membranes for Anion Exchange Membrane Fuel Cells

Dimethylimidazolium-Functionalized Polybenzimidazole and Its Organic–Inorganic Hybrid Membranes for Anion Exchange Membrane Fuel Cells

Synthesis, Characterization, Surface Properties and Micellization Behaviour of Imidazolium‐based Ionic Liquids

Density functional theory study on the degradation of fuel cell anion exchange membranes via removal of vinylbenzyl quaternary ammonium head group

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