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A series of cross‐linked AEMs (c‐DQPPO/PVA) are synthesized by using rigid polyphenylene oxide and flexible poly(vinyl alcohol) as the backbones. Dual cations are grafted on the PPO backbone to improve the ion exchange capacity (IEC), while glutaraldehyde is introduced to enhance compatibility and reduce swelling ratio of AEMs. In addition to the enhanced mechanical properties resulting from the rigid‐flexible cross‐linked network, c‐DQPPO/PVA AEMs also exhibit impressive ionic conductivity, which can be attributed to their high IEC, good hydrophilicity of PVA, and well‐defined micro‐morphology. Additionally, due to confined dimension behavior and ordered micro‐morphology, c‐DQPPO/PVA AEMs demonstrate excellent chemical stability. Specifically, c‐DQPPO/PVA‐7.5 exhibits a wet‐state tensile strength of 12.5 MPa and an elongation at break of 53.0 % at 25 °C. Its OH− conductivity and swelling degree at 80 °C are measured to be 125.7 mS cm−1 and 8.2 %, respectively, with an IEC of 3.05 mmol g−1. After 30 days in a 1 M NaOH solution at 80 °C, c‐DQPPO/PVA‐7.5 experiences degradation rates of 12.8 % for tensile strength, 27.4 % for elongation at break, 14.7 % for IEC, and 19.2 % for ion conductivity. With its excellent properties, c‐DQPPO/PVA‐7.5 exhibits a peak power density of 0.751 W cm−2 at 60 °C in an H2‐O2 fuel cell. [ABSTRACT FROM AUTHOR]

Balancing ion conductivity, mechanical strength, and alkali stability is a significant challenge in the application of anion exchange membranes (AEMs) in anion exchange membrane fuel cells (AEMFCs). In this study, rigid poly(4-vinylbiphenyl chloride) (PVB) and flexible polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS) are selected as the polymer backbones to create semi-interpenetrating network (SIPN) AEMs. To achieve high ionic conductivity, quaternary ammonium groups are grafted onto each PVB structural unit, and TMHDA reacts with CMSEBS to construct a cross-linking network while also generating quaternary ammonium groups. This approach, along with well-defined micro-morphology, result in SIPN-SEBS/PVB-10 exhibiting an impressive ionic conductivity of 105.7 mS cm−1 at 80 °C. The SIPN structure, formed by the linear quaternary ammonium PVB and cross-linked SEBS, enhances the compatibility between the rigid and flexible components, resulting in good tensile strength (>14.5 Mpa) and elongation at break (>31.8%) for SIPN-SEBS/PVB AEMs at 25 °C in the wet state. Furthermore, SIPN-SEBS/PVB AEMs exhibit excellent chemical stability, in addition to the restricted swelling behavior, which can be attributed to the stable PVB and SEBS main chains. After immersion in a 1 M NaOH solution at 80 °C for 30 days, the degradation of backbones and cations in all membranes is less than 10% and 20%, respectively. Moreover, the peak power density of SIPN-SEBS/PVB-10 in an H 2 /O 2 single fuel cell reaches an impressive value of 379 mW cm−2. Based on these excellent properties, the developed SIPN AEMs hold great promise as candidates for AEMFCs. Structure diagram and photos of SIPN-SEBS/PVB AEMs. And the single fuel cell performance by using SIPN-SEBS/PVB-10 as the separator. [Display omitted] • A new perspective is offered on the development of AEMs with high performance. • Semi-interpenetrating network AEMs is achieved using linear QPVB and cross-linked c QSEBS. • A peak power density of 379 mW cm−2 is presented. [ABSTRACT FROM AUTHOR]

A series of highly transparent semi-interpenetrating polymer network anion exchange membranes (SIPN AEMs) composed of a flexible and cation cross-linked polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (c QSEBS) component, and a rigid, highly-charged quaternized poly(2,6-dimethyl phenylene oxide) (QPPO) component are prepared. Flexible and rigid polymer backbones endow SIPN AEMs with excellent flexibility and mechanical strength. High charge content and well defined hydrophilic/hydrophobic phase separation patterns ensure SIPN AEMs with improved ionic conductivity. Alkali-resistant SEBS, enhanced dimensional stability and ordered microphase separation morphology contribute to the good chemical stability of SIPN-AEMs. Among these AEMs, SIPN- c QSEBS/QPPO-10 with an IEC of 1.93 mmol g−1 achieves a better trade-off between tensile strength (19.36 MPa at 25 °C in wet state), flexibility (58.43% at 25 °C in wet state) and OH− conductivity (103.1 mS cm−1 at 80 °C). Besides, SIPN- c QSEBS/QPPO-10 shows low swelling degree (15.4% at 80 °C) and high chemical stability (95.9%, 88.7%, 82.7% and 88.5% retention in weight, OH− conductivity, tensile strength and elongation at break, respectively, after immersing in 1 M NaOH at 80 °C for 30 days). Importantly, a fuel cell peak power density of 1.174 W cm−2 is obtained at 80 °C by using SIPN- c QSEBS/QPPO-10 as the separator. Compared with original cross-linked c QSEBS, the semi-interpenetrating network AEM of SIPN- c QSEBS/QPPO-10 exhibits enhanced mechanical properties, improved ionic conductivity and elevated fuel cell performance. [Display omitted] • Highly transparent SIPN AEMs based on PPO and SEBS backbones are prepared. • Good balance achieves among conductivity, mechanical properties and chemical stability. • An AEMFC performance of 1.174 W cm−2 for SIPN- c QSEBS/QPPO-10 is obtained. [ABSTRACT FROM AUTHOR]

In order to achieve a better trade-off among ionic conductivity, mechanical strength and chemical stability, a series of novel aggregated and ionic cross-linked anion exchange membranes (AEMs) are recommended, namely, ac S 6 QAPSF, ac S 8 QAPSF and ac S 10 QAPSF. Cross-linked network shoulders the responsibility to toughen the ac S x QAPSF. Appropriate micro-morphology is responsible for facilitating the conduction of OH− and improving the alkaline stability of the ac S x QAPSF. Compared with the original QAPSF, ac S x QAPSF membranes exhibit much better properties. Specifically, for ac S 8 QAPSF, a high OH− conductivity of 90.5 mS cm−1 is achieved at 80 °C, with the swelling degree of 10.0%. The tensile strength and elongation at break of wet ac S 8 QAPSF at 25 °C are 23.9 Mpa and 21.1%, respectively. After testing in 1 M NaOH at 80 °C for 30 days, the weight loss of ac S 8 QAPSF is 8.0%, with the losses of tensile strength and elongation at break of 13.8% and 13.3%, respectively. Its IEC and IC retentions are 92.0% and 90.5%, respectively. For ac S 8 QAPSF, a fuel cell peak power density of 0.612 W cm−2 is obtained at 60 °C. While for QAPSF, its fuel cell peak power density is only 0.101 W cm−2, and the film is cracked after the 30 days stability test. The unique ac S x QAPSF membrane can alleviate the tradeoff among ionic conductivity, mechanical strength and chemical stability. Image 1 • Novel aggregated and ionic cross-linked AEMs based on PSF are synthesized. • An important insight into the design of AEMs with high performance is provided. • The fuel cell of ac S 8 QAPSF achieved a peak power density of 612 mW cm−2 at 60 °C. [ABSTRACT FROM AUTHOR]