Synthesis and characterization of perfluoro quaternary ammonium anion exchange membranes

Abstract

In this study, new alkaline exchange membranes were prepared from the perfluorinated 3M ionomer with various quaternary ammonium cations attached with sulfonamide linkage. The degree of functionalization varied depending on the cation species, resulting in different ion exchange capacities (IECs), 0.33–0.72 meq g−1. There was evidence of polymer degradation when the films were exposed to hydroxide, and hence all membrane characterization was performed in the chloride form. Conductivity was dependent on cation species and IEC, Ea = 36–59 kJ mol−1. Diffusion of water through the membrane was relatively high 1.6 × 10−5 cm2 s−1 and indicated restriction over a range of diffusion times, 6–700 ms. Water uptake (WU) in the membranes was generally low and the hydration level varied based on cation species, λ = 6–11. Small‐angle scattering experiments suggested ionic aggregation, 37–42 Å, independent of cation species but slight differences in long‐range order with cation species. © 2012 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1761–1769, 2013

Effect of hydration on the mechanical properties and ion conduction in a polyethylene-b-poly(vinylbenzyl trimethylammonium) anion exchange membrane

“…These conductivities are similar to other AEMs with similar IECs [12,30,31]. The activation energy of the PEb-PVBTMA membrane is higher than standard PEMs [32] and similar to slightly higher than AEMs [30,33].…”

Synthesis of perfluorinated ionomers and their anion exchange membranes

“…Besides the hydrolysis of sulfonyl fluoride groups, PFSO 2 F precursor is insoluble in common solvents which greatly increase the difficulty in polymer reaction. The unreacted -SO 2 F group was found in the membrane, which leads the low IEC of the membrane as well as low conductivity [24]. Therefore, a soluble and base-resistant perfluorinated polymer and AEMs are desired.…”

“…Recently, several studies have report on the perfluorinated AEMs from Nafion s or 3 M perfluorosulfonyl fluoride (PFSO 2 F) precursor via amination of the PFSO 2 F precursor with variety of covalently attached cations including trimethylammonium (TMA), 1, 4 -dimethylpiperazine (DMP), quaternized 1, 4-diazabicyclo [2.2.2] octane(DABCO) and guanidinium, and so on [22][23][24][25][26]28]. The F À form AEMs can be generated by the reaction of the 3 M or Nafion s precursor performed under rigorously anhydrous conditions.…”

“…Furthermore, attribute to perfluorinated backbone, PFSA membranes are chemically and thermally stable and have good mechanical properties [19][20][21]. Due to the unique structure and successful applications of PFSA in PEMFCs, many efforts have been made to introduce Teflon type backbone into the field of the AEMFCs [22][23][24][25][26]. For AEMFCs, perfluorinated AEMs are most promising AEMs because of their base-resistant and the extremely hydrophobic nature of the perfluorinated backbone which has enough force to satisfactorily drive the phase-separation that expected to improve ion conduction in AEMs [27].…”

The impact of alkyl tri‐methyl ammonium side chains on perfluorinated ionic membranes for electrochemical applications

“…Because the starting material for this polymer is the 3 M‐PFSA, this feature could be the “ionomer peak” which is typically observed in PFSAs . This feature arises due to ionic aggregates of the polymer which absorb water and swell at higher humidity values . The d‐spacing can be given by: …”