Opening Doors to Future Electrochemical Energy Devices: The Anion‐Conducting Polyketone Polyelectrolytes

Abstract

The numerous potential benefits of incorporating anion‐exchange membranes (AEMs), in place of proton‐exchange membranes (PEMs), in energy storage and conversion technologies renders their development of fundamental importance for the continued evolution of alternative energy systems. However, the widespread implementation of AEMs is currently plagued by a range of problems including lower conductivity (with respect to PEMs), poor stability, and high cost. This study reports the conversion of polyketone, one of the world's most mass produced and cheap polymers, to a new highly tuneable polymer architecture, functionalized polyketone (FPK), that demonstrates a range of excellent properties rendering it a significant prospect for AEM materials. The thermal, processing, and ion‐conducting properties of FPK are governed by the amount and nature of the newly formed N‐substituted pyrrole pendant side groups. At 80 °C, the quarternized pyridyl FPK derivative (4MPyrFPK) yields ion‐conductivities of 8.6 and 10.5 mS cm−1 in the iodide and hydroxide forms. In addition, the hydroxide form of 4MPyr‐FPK demonstrates remarkable stability toward the typically problematic alkaline conditions. No chemical decomposition is observed to the membrane after imbibing it in KOH solution for 72 h, and furthermore, the ion‐conductivity is demonstrated to remain constant for at least 30 d at 80 °C.

Inorganic‐Organic Hybrid Anion Conducting Membranes Based on Ammonium‐Functionalized Polyethylene Pyrrole‐Polyethylene Ketone Copolymer

“…The sharp band at 1690 cm −1 is associated with the stretching of the carbonyl bonds in α form, which is shifted to a higher frequency in FPK and all its derivate as in low molecular weight aliphatic PKs, indicating the delocalized nature of backbone covalent bonds. [ 15 ] Furthermore, the bands associated with NH 2 of the pristine amine are not present in the spectra of FPKs which indicates the conversion of 1,4‐dicarbonyl units into pyrrole moieties, as confirmed by the decrease in the band intensity associated with C═O stretching in all FPKs. The most important feature indicating the formation of pyrrole moieties is the presence of the new bands at 1642 and 1571 cm −1 which are associated with the CN and C═C bonds stretching of the N‐heterocycle.…”

“…The most important feature indicating the formation of pyrrole moieties is the presence of the new bands at 1642 and 1571 cm −1 which are associated with the CN and C═C bonds stretching of the N‐heterocycle. [ 15 ] In addition, the bands at 1422 and 1299 cm −1 are ascribed to ν (CN) of the pyrrole ring, while the sharp one at 741 cm −1 corresponds to its CH (oop) bending, [ 32 ] as observed in the spectrum of the model compound 1,3,5‐trimethylpyrrole. No substantial changes could be noticed in the membrane after hot‐pressing which is indicative of the retention of the functionalized polymer structure (see Figure S3, Supporting Information).…”

“…In their functionalized form, the FPKs powder can be easily dissolved in dimethyl formamide for casting or electrospinning in the preparation of membranes. [ 15 ]…”

Enhanced OH− Conductivity for Fuel Cells with Anion Exchange Membranes, Based on Modified Terpolymer Polyketone and Surface Functionalized Silica

“…PK is a promising polymer because the starting raw materials (carbon monoxide and ethylene monomers) are commonly available and inexpensive. Using PK is also an outstanding strategy for synthesizing functional polymers with pendant-charged aromatic groups through one of the most classical approaches, known as the Paal-Knorr reaction [23][24][25]. In our previous work, a thorough investigation of the chemical features of modified silica and its interaction with modified PK was conducted using Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR).…”

Electrochemical synthesis of ion exchange polymers: Comparison between hydroxide and proton conductors

“…Ion exchange polymers are fascinating materials with a wide range of applications, including to name but a few, electrochemical energy storage and conversion [1][2][3][4], water purification by ultrafiltration or electrodialysis [5][6][7], or sensors and actuators [8,9]. In ionomers, a nanophase separation is generally observed with hydrophobic domains containing the ionomer backbone (often perfluorinated aliphatic [10][11][12] or aromatic hydrocarbon chains [13][14][15][16][17]) and nanometric channels containing the dissociated ions and a solvent with high dielectric constant, typically water [18][19][20].…”