Polymeric organic mixed ionic–electronic conductors underpin several technologies in which their electrochemical properties are desirable. These properties, however, depend on the microstructure that develops in their aqueous operational environment. We investigated the structure of a model organic mixed ionic–electronic conductor across multiple length scales using cryogenic four-dimensional scanning transmission electron microscopy in both its dry and hydrated states. Four-dimensional scanning transmission electron microscopy allows us to identify the prevalent defects in the polymer crystalline regions and to analyse the liquid crystalline nature of the polymer. The orientation maps of the dry and hydrated polymers show that swelling-induced disorder is mostly localized in discrete regions, thereby largely preserving the liquid crystalline order. Therefore, the liquid crystalline mesostructure makes electronic transport robust to electrolyte ingress. This study demonstrates that cryogenic four-dimensional scanning transmission electron microscopy provides multiscale structural insights into complex, hierarchical structures such as polymeric organic mixed ionic–electronic conductors, even in their hydrated operating state.

聚合物有机混合离子-电子导体是其电化学特性所需的几种技术的基础。然而，这些特性取决于在其水性操作环境中形成的微观结构。我们使用低温四维扫描透射电子显微镜研究了干燥和水合状态下多个长度尺度的模型有机混合离子-电子导体的结构。四维扫描透射电子显微镜使我们能够识别聚合物结晶区域中的普遍缺陷，并分析聚合物的液晶性质。干燥和水合聚合物的取向图表明，溶胀诱导的无序主要局限于离散区域，从而在很大程度上保持了液晶的有序性。因此，液晶介观结构使电子传输对电解质的进入具有鲁棒性。这项研究表明，低温四维扫描透射电子显微镜为复杂的分层结构（例如聚合物有机混合离子-电子导体）提供了多尺度结构见解，即使在其水合运行状态下也是如此。