Stable Double Gyroid Structures in Ionic-Aliphatic Multiblock Copolymers

离子传输聚合物是能源应用和膜的关键材料。作为快速链动力学作为有效离子传输的基础的替代方案，离子可以布置在合适的渗滤液聚集结构中。这可以有利地将离子传输动力学与基质动力学解耦，这不仅可以有益于传输速率，而且同时还提供结构稳定的有序基质材料。为此，双连续结构特别令人感兴趣，然而，实现这样的结构化材料是具有挑战性的。双螺旋体（DG）形态由于其结构的复杂性而被描述，其由两个相互贯穿的次要组分网络组成，它们与基质一起代表双连续结构。除了改善输运性质之外，DG形态的分散域与更简单的形态相比还可以增强机械性质。在我们的初步工作中，我们建立了磺化聚酯与长链脂肪族重复单元表现为（AB）n多嵌段共聚物在其相行为。即使当两个交替嵌段AB的组合长度低至18个碳原子时，高度不相容的极性离子和非极性烃链段也会分离。出乎意料的是，这样的离子-脂肪族多嵌段共聚物（IAMBC）在熔体中可以采用DG结构，具有理想的亚10 nm的长度尺度。然而，由于聚合物的脂族单元在此被设计成结晶成目标层状结构，因此这些DG在环境条件下不稳定。提出的研究的目的是设计和访问DG形态稳定在环境条件下。我们将阐明非极性非结晶烃重复单元图案，提供微相分离的离子脂肪族多嵌段共聚物成DG形态。为此，我们将制定出合成路线的单体预期提供高反应性的缩聚反应，并提供非结晶重复单元也有利于适应DG形态的表面曲率。作为一种补充方法，将探讨永久固定DG形态的交联策略。作为一个先决条件的聚合度和形态的相关性的理解将建立。将实施直接在聚合期间或经由聚合后交联的交联方法。这种交联还预期增强靶材料的稳健性，例如增强对可增强离子迁移率的溶剂的耐受性。将获得对这些形态产生的离子传导和机械性能的第一见解。在更广泛的意义上，我们预期的理解这种特殊系统的微观结构-形态关系将有助于合理设计新材料，例如具有上级机械稳定性和离子导电性。

Ion transporting polymers are key materials for energy applications and membranes. As an alternative to fast chain dynamics as the basis of efficient ion transport, ions may be arranged in suitable percolate aggregated structures. This can advantageously decouple the ion transport dynamics from the matrix dynamics, which may not only benefit transport rates but at the same time also provide structurally stable ordered matrix materials. Bi-continuous structures are of particular interest to this end, however, achieving such structured materials is challenging. The double gyroid (DG) morphology intrigues by its structural complexity, being composed of two interpenetrating networks of the minor component which together with the matrix represent a bi-continuous structure. Beyond improving transport properties, the percolated domains of DG morphologies can also enhance mechanical properties compared to simpler morphologies. In our preliminary work we established that sulfonated polyesters with long-chain aliphatic repeat units behave as (AB)n multiblock copolymers in their phase behavior. The highly incompatible polar ionic and apolar hydrocarbon segments segregate even when the combined length of two alternating blocks AB is as low as eighteen carbon atoms. Unexpectedly, such ionic-aliphatic multiblock copolymers (IAMBCs) in the melt can adopt DG structures, with desirable sub-10 nm length scales. However, as the polymers' aliphatic units were designed here to crystallize to target layered structures these DGs are not stable at ambient conditions. The objective of the research proposed is to design and access DG morphologies stable at ambient conditions. We will elucidate apolar non-crystallizable hydrocarbon repeat unit motifs that afford microphase phase separation in ionic-aliphatic multiblock copolymers into DG morphologies. For this purpose we will work out synthetic routes to monomers anticipated to provide high reactivity for polycondensation and to afford non-crystallizing repeat units also favorable for adapting to the surface curvature of the DG morphology. As a complimentary approach, crosslinking strategies to permanently fixate the DG morphologies will be explored. As a prerequisite an understanding of the correlation of degrees of polymerization and morphology will be established. Cross-linking methodology directly during polymerization or via post-polymerization cross-linking will be implemented. This cross-linking is also expected to enhance the robustness of the target materials, for example to enhance resistance towards solvents that can enhance ion mobility. First insights into the ion conducting and mechanical properties resulting from these morphologies will be gained. In a broader sense, our anticipated understanding of microstructure-morphology relationships of this exceptional system will be instrumental to rationally design novel materials with for example superior mechanical stability and ion conductivity.