英国帝国理工学院宋启磊团队报道了通过聚合物膜水合微孔的选择性离子传输。相关研究成果发表在2024年11月6日出版的《自然》。

离子传导聚合物膜在许多分离过程和电化学装置中都是必不可少的，包括电渗析、氧化还原液流电池、燃料电池和电解槽。控制这些膜中的离子传输和选择性在很大程度上取决于孔径的操纵。

尽管膜孔结构可以在干燥状态下设计，但由于电解质溶液中的膨胀，它们在水合作用后被重新定义。控制孔隙水化的策略和对孔隙结构演变的更深入理解对于精确调整孔径至关重要。

该文中，研究人员报告了含有不同疏水性侧基的聚合物膜，这些侧基战略性地位于带电基团附近，以调节其水合能力和孔膨胀。调节水合微孔尺寸（小于2纳米）可以直接控制水和离子在宽长度尺度上的传输，如光谱和计算方法所量化的。

在由更多疏水侧基形成的水合抑制孔中，离子选择性得到改善。与传统膜相比，这些高度互联的离子传输通道具有可调的孔栅尺寸，显示出更高的离子电导率和更低的氧化还原活性物种渗透速率，使能量密集的水性有机氧化还原液流电池能够稳定循环。

该孔径定制方法为具有精确控制的离子和分子传输功能的膜，提供了一条有前景的途径。

附：英文原文

Title: Selective ion transport through hydrated micropores in polymer membranes

Author: Wang, Anqi, Breakwell, Charlotte, Foglia, Fabrizia, Tan, Rui, Lovell, Louie, Wei, Xiaochu, Wong, Toby, Meng, Naiqi, Li, Haodong, Seel, Andrew, Sarter, Mona, Smith, Keenan, AlvarezFernandez, Alberto, Furedi, Mate, Guldin, Stefan, Britton, Melanie M., McKeown, Neil B., Jelfs, Kim E., Song, Qilei

Issue&Volume: 2024-11-06

Abstract: Ion-conducting polymer membranes are essential in many separation processes and electrochemical devices, including electrodialysis1, redox flow batteries2, fuel cells3 and electrolysers4,5. Controlling ion transport and selectivity in these membranes largely hinges on the manipulation of pore size. Although membrane pore structures can be designed in the dry state6, they are redefined upon hydration owing to swelling in electrolyte solutions. Strategies to control pore hydration and a deeper understanding of pore structure evolution are vital for accurate pore size tuning. Here we report polymer membranes containing pendant groups of varying hydrophobicity, strategically positioned near charged groups to regulate their hydration capacity and pore swelling. Modulation of the hydrated micropore size (less than two nanometres) enables direct control over water and ion transport across broad length scales, as quantified by spectroscopic and computational methods. Ion selectivity improves in hydration-restrained pores created by more hydrophobic pendant groups. These highly interconnected ion transport channels, with tuned pore gate sizes, show higher ionic conductivity and orders-of-magnitude lower permeation rates of redox-active species compared with conventional membranes, enabling stable cycling of energy-dense aqueous organic redox flow batteries. This pore size tailoring approach provides a promising avenue to membranes with precisely controlled ionic and molecular transport functions.

DOI: 10.1038/s41586-024-08140-2

Source: https://www.nature.com/articles/s41586-024-08140-2