Abstract With the aim to enhance the hydrophilic–hydrophobic separation and thus improve the anion conductivity of diblock copolymer anion exchange membranes (AEMs), a fluorinated hydrophobic block was introduced into quaternized diblock copolystyrene. Two fluoro-containing monomers (i.e., 4-fluorostyrene (4FS) and 2, 3, 4, 5, 6-pentafluorostyrene (PFS)) were polymerized into a poly(4-vinyl benzyl chloride)-based macroinitiator (Macro-PVBC263) via reversible addition–fragmentation chain transfer (RAFT) polymerization. This route led to the corresponding diblock copolymers PVBC263-b-P4FSy and PVBC263-b-PPFSy, which served to prepare AEMs (i.e., PVBC263-b-PPFSy-OH and PVBC263-b-P4FSy-OH, respectively) via quaternization with trimethyl amine (TMA) and subsequent ion-exchange. As expected, the as-obtained AEMs showed well-defined lamellar morphologies, as revealed by small-angle X-ray scattering (SAXS) and atomic force microscopy (AFM). Consequently, all the fluorinated diblock copolymer-based AEMs showed high anion conductivities. PVBC140-b-P4FS38-OH showed the highest hydroxide conductivity (86.1 mS/cm) with an ion exchange capacity (IEC) of 4.27 meq/g. Interestingly, despite its high IEC, PVBC263-b-P4FS38-OH showed a reasonable water uptake (WU) of 37.5% as a result of the presence of hydrophobic fluorinated block segments. Thus, proper ion conducting channels are believed to be built by facilitating hydrophilic–hydrophobic phase separation processes driven by the fluoro-substituted functionalities. Despite their high IEC values in terms of hydrophobicity, the WU and swelling ratio of the AEMs prepared herein did not increase significantly, especially at elevated temperatures. All the AEMs preserved over 86% of their initial hydroxide conductivity after 20 d of alkaline stability testing (1 M aqueous NaOH) at 80 °C.

中文翻译：

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基于含有氟化疏水嵌段的季铵化双嵌段共聚苯乙烯的新型阴离子交换膜

摘要 为了增强亲水-疏水分离，从而提高二嵌段共聚物阴离子交换膜（AEM）的阴离子电导率，将氟化疏水嵌段引入季铵化二嵌段共聚苯乙烯中。两种含氟单体（即4-氟苯乙烯（4FS）和2, 3, 4, 5, 6-五氟苯乙烯（PFS））聚合成聚（4-乙烯基苄基氯）基大分子引发剂（Macro-PVBC263）通过可逆加成-断裂链转移（RAFT）聚合。该路线导致相应的二嵌段共聚物 PVBC263-b-P4FSy 和 PVBC263-b-PPFSy，它们用于通过三甲基季铵化制备 AEM（即分别为 PVBC263-b-PPFSy-OH 和 PVBC263-b-P4FSy-OH）胺（TMA）和随后的离子交换。正如预期的那样，所获得的 AEM 显示出明确的层状形态，正如小角度 X 射线散射 (SAXS) 和原子力显微镜 (AFM) 所揭示的那样。因此，所有基于氟化二嵌段共聚物的 AEM 都显示出高阴离子电导率。PVBC140-b-P4FS38-OH 显示出最高的氢氧化物电导率 (86.1 mS/cm)，离子交换容量 (IEC) 为 4.27 meq/g。有趣的是，尽管具有高 IEC，但 PVBC263-b-P4FS38-OH 由于存在疏水性氟化嵌段链段而显示出 37.5% 的合理吸水率 (WU)。因此，适当的离子传导通道被认为是通过促进由氟取代官能团驱动的亲水-疏水相分离过程来建立的。尽管它们在疏水性方面的 IEC 值很高，但本文制备的 AEM 的 WU 和溶胀比并未显着增加，尤其是在升高的温度下。