Preparation of Random Polymers by Copolymerization of Rigid-Twisted Spirobiindane with Poly(aryl isatin) for High-Performance Anion Exchange Membranes

Abstract

Designing the packing of polymer chains with reasonable fraction free volume (FFV) is regarded as an effective way to improve the conductivity of polymer-based membranes. We synthesize random polymers by copolymerization of bulky rigid-twisted spirobiindane, isatin, and one of the joint groups p-terphenyl, biphenyl, and 1,2-diphenylethane. The polycondensation reaction is catalyzed by trifluoromethanesulfonic acid. The introduced spirobiindane segments enlarge the distance of polymer chains and increase the FFV of the membrane. The formation of the microphase separation structure is evidenced according to the results of transmission electron microscopy and atomic force microscopy. As a result, a hydroxide conductivity of 126.7 mS cm–1 is achieved at 80 °C by the poly­(spirobiindane diphenyl isatin)-based membrane (QP­(SBP/BP)-20). The retention rates in hydroxide ion conductivity are 89.7 and 84.0% after soaking the membrane in 1 M KOH for 1152 h and in 4 M KOH for 628 h at 80 °C, respectively. The QP­(SBP/BP)-20 membrane-based single-fuel cell exhibits an open-circuit voltage of 0.99 V and a peak power density of 744 mW cm–2 at 60 °C by fueling with humidified H2 and O2 with 0.05 MPa back pressure.

Novel Hydrophobic Covalent Cross-Linking Poly(terphenyl Isatin Piperidinium) with Poly(triphenylpyridine) for Anion Exchange Membranes

“…Comparison of (a) IEC, SR (80 °C), and WU (80 °C) and (b) OH – ion conductivity (80 °C) and Ts and Eb of the PTAP–PTBINP-Q x and other AEMs in the recent reports. ,,,− …”

“…When the cross-linking degree increases, the Ts of the membranes increased from 43.15 to 77.61 MPa and Eb decreased from 16.54% to 10.67%. The mechanical properties of some AEMs based on istain or pyridine backbones are shown in Figure b. ,,,− After cross-linking, the PTAP–PTBINP-Q x compared to other membranes becomes softer and has good mechanical properties. At similar conductivity levels, the Ts and Eb values of the membrane can be controlled to a certain extent, which can meet the practical requirements of membrane electrode preparation and fuel cell assembly.…”

“…AEM, as the indispensable component of membrane electrode assembly (MEA), plays a role in transmitting hydroxide ions, separating the anode and cathode, and effectively blocking the transfer of fuel gas between electrodes in anion exchange membrane fuel cells (AEMFCs). − AEM is composed of hydrophobic polymer backbones that provide conductive group loading sites and the mechanical properties of the membrane. The hydrophilic cationic groups grafted onto the polymer main chain provide anchoring points for anion transfer.…”

Aryl ether-free polymer electrolytes for electrochemical and energy devices

“…For aryl ether-PAs, most studies used BTMA, likely because quaternization with trimethylamine in the chloromethylated or methylbrominated phenyl is well-established. For aryl ether-free PArs, alkaline-stable cationic functional groups such as alkyl ammonium (alkyl-A) 168,230,544–554 or phenyl-piperidinium (phenyl-PiP) 184,478,551,555–561 are prevalent as cationic functional groups. Other alkaline-stable cationic functional groups such as benzimidazolium 562 and alkyl piperidinium 563–565 have been frequently used as well.…”

Construction of Cross-Linked Poly(aryl Ether Nitrile) Anion Exchange Membranes Containing Bilateral Linked Branches for Water Electrolyzer

“…The structure of CS-G-PAENA-50 provided a multitude of ion transport channels, facilitating efficient ion transport and enabling high conductivity of the membrane. 39,40 The domain spacing of the AEMs was further investigated by SAXS experiments to elucidate the presence of ion clusters. A more pronounced scattering peak indicated a denser arrangement of hydrophilic groups within the membrane and also suggested a larger spacing between ionic conductive channels.…”