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Novel high temperature polymer electrolyte membranes (HT-PEMs) are fabricated from commercial and low-cost poly (ether ketone cardo) (PEK-Cardo). Rather than normal chloromethylation and quaternization procedure to introduce basic groups into poly (arylene ether)s, three different long side-chain basic groups are grafted into PEK-Cardo through a facile one-step lactamization between the cardo phenolphthalein type moiety in PEK-Cardo and amino compounds (i.e. 1-(3-aminopropyl) imidazole (APIm), 1-(3-aminopropyl) pyrrolidin-2-one (APy) and 3-(dimethylamino)-1-propylamine). The obtained lactamized PEK-Cardo membranes exhibit excellent phosphoric acid doping capability and the physicochemical properties are optimized by adjusting the chemical structure and grafting degree of side-chain basic groups. Fuel cell results demonstrate a big potential for HT-PEM fuel cell applications. Thus, this proposal provides a new, straightforward and low-cost method to prepare high-performance HT-PEMs. [Display omitted] • HT-PEMs are prepared via a facile one-step lactamization between PEK-Carod and amino compounds. • The obtained lactamized PEK-Cardo membranes exhibit excellent PA doping capability and high conductivity. • Fuel cell results demonstrate a big potential for HT-PEMFC applications. [ABSTRACT FROM AUTHOR]

• Various mono- or bis-imidazoles functionalized PVC membranes are fabricated. • Membranes with flexible linkage containing bis-imidazoles exhibit high PA doping level and good conductivity. • Mechanical stability is improved by blending PTFE as an enhanced material. Low cost poly(vinyl chloride) (PVC) is functionalized by eight different imidazole compounds to fabricate high temperature polymer electrolyte membranes. Due to the presence of chloride naturally in the backbone, PVC reacts with various imidazoles via the S N 2 nucleophilic reaction avoiding the chloromethylation reaction. Different from previous imidazolium groups grafted chloromethyl polymers, PVC membranes functionalized with mono-imidazoles (such as methylimidazole, dimethylimidazole, 1-butyl-2-methyl-imidazole and 1-decyl-2-methyl imidazole) exhibit quite low phosphoric acid doping contents. Bis-imidazole compounds (including 1,4-bis(imidazolyl)butane (7#) and 1,4-bis(2-methylimidazol-1-yl)butane) are synthesized to be used as the imidazolium functionalized reagents. PVC membranes grafted by bis-imidazoles with the long and flexible linkage display superior acid doping capability and high conductivities. Meanwhile, porous poly(tetrafluoroethylene) (PTFE) is employed as the enhanced matrix to improve the mechanical strength. The resultant PVC-42%7#/PTFE membrane with a phosphoric acid doping content of 100.7% shows a volume swelling of 64%, a conductivity of 41.8 mS·cm−1 at 160 °C without humidification, and a tensile strength of 14.2 MPa at room temperature, whose fuel cell performance is determined to demonstrate the technical feasibility for fuel cells. [ABSTRACT FROM AUTHOR]

New long side-chain imidazolium functionalized poly(vinyl chloride) membranes with low cost and high performance are developed for the vanadium redox flow battery. [Display omitted] • 1-(3-Aminopropyl)imidazole functionalized PVC membranes are synthesized for VRFBs. • Incorporation of APIm endows APIm-PVC membranes with excellent SA absorption capability. • 80%APIm-PVC achieves a 5 times higher ion selectivity than Nafion 115. • VRFB with 80%APIm-PVC displays high battery efficiencies and excellent cycle constancy. Developing polymer membranes with low price, superior ion conduction and good vanadium ion transport resistance is currently a hot topic in vanadium redox flow batteries (VRFBs). In the present work, long side-chain imidazolium functionalized poly(vinyl chloride) (PVC) membranes are fabricated to provide a versatile strategy for the ion transport and selectivity trade-off in VRFBs. PVC is employed as the membrane matrix owing to its low price, high tensile strength and natural chlorine groups. 1-(3-Aminopropyl) imidazole (APIm) is grafted into PVC via a facile nucleophilic reaction, which provides the basic groups as the interaction sites for sulfonic acid, resulting in low area resistance. Meanwhile, due to the electrostatic repulsion effect of positively charged imidazolium cations between vanadium ions, APIm-PVC membranes display low vanadium ion permeability. Consequently, the 80 %APIm-PVC membrane has both low area resistance of 0.268 Ω∙cm2 and low vanadium ion permeability of 9.0 × 10−8 cm2∙min−1 simultaneously, achieving a 5 times higher ion selectivity (2.65 × 105 S min cm−3) than Nafion 115 (0.52 × 105 S min cm−3). The VRFB equipped with the 80 %APIm-PVC membrane shows higher battery efficiencies than the cell with Nafion 115 ranging from 100 to 160 mA∙cm−2, and also possesses excellent cycle constancy, indicating that low-cost x %APIm-PVC membranes have a great application potentiality for VRFBs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Low-cost membranes for VFRBs are synthesized by crosslinking PEI with PEKC. • x %PEI-PEKC membranes exhibt low AR and low VO2+ permeability simultenously. • The 50%PEI-PEKC membrane displays superior VRFB efficiencies and cycling stability. Developing polymer membranes with low cost, high ionic conduction and low vanadium ion permeability simultaneously for the vanadium redox flow battery (VRFB) is a huge challenge to macromolecule design and engineering. Herein, a series of high-performance and low-cost macromolecule cross-linked membranes for VRFB are synthesized from cardo-poly(etherketone) (PEKC) and poly(ethylene imine) (PEI) through a straightforward lactamization reaction between the primary amines in PEI and lactones in PEKC. Owing to the acid-base interaction between amino groups of PEI and sulfonic acid (SA), crosslinked x %PEI-PEKC membranes exhibit excellent SA adsorption capability and low area resistance. Meanwhile, the formed macromolecule multi-crosslinked networks significantly improve the membrane-forming property of PEI and endow membranes with superior mechanical rigidity and low vanadium ion permeability simultaneously. Consequently, the 50%PEI-PEKC membrane exhibit a nearly 90 times higher ion selectivity of 24.71 × 105 S min cm−3 than Nafion 115. The assembled VRFB with 50%PEI-PEKC displays higher battery efficiencies than Nafion 115 at 60–160 mA cm−2, which also possesses superior cycling stability at 100 mA cm−2. [ABSTRACT FROM AUTHOR]