Self assembly, dynamics and charge transport in bulk ionic liquids and ionogels

本体离子液体和离子凝胶中的自组装、动力学和电荷传输

• 批准号: 417469938
• 负责人: Professor Dr. Thomas Blochowicz
• 金额: --
• 依托单位: School of Physics & Astronomy
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/417469938?language=en
• 关键词: Self; assembly; dynamics; charge; transport

Ionic Liquids (ILs), i.e. molten salts that are liquid at room temperature, are liquids with unusual properties that have many potential applications, e.g. in what is known as "green chemistry" or in energy applications. Many ionic liquids, due to their amphiphilic molecular architecture, tend to show self-assembly and structure formation on the mesoscale (i.e. formation of polar and apolar domains), which influences molecular dynamics and ion transport in these materials. It is the aim of the current project to understand, how charge transport and molecular dynamics depend on the ionic liquid mesostructure, with particular emphasis on coupling/decoupling phenomena of charge transport and structural relaxation in these systems.Therefore in this project a series of Ils with varying tendency to form polar/apolar domains is investigated (realized, e.g. by varying the alkyl chain length of a cation or by addition of small amounts of solvents) with respect to molecular dynamics and ion transport. In the next step it is planned to investigate Ils in ionogels. The latter systems are based on ionic liquids by adding various network forming agents. In these materials high conductivity is often combined with almost solid-like mechanical properties, which makes them particularly interesting for many applications. In the ionogels the effect of inner surfaces on the IL structure formation and on dynamics and charge transport are to be clarified. In particular, interesing effects are expected when the length scale of geometric confnement by the network forming agent meets the lengthscale of domains and aggregates in the IL. In terms of experimental method, the emphasis in the current project is on depolarized dynamic light scattering, which unambiguously identifies molecular reorientation and is not influenced by charge transport or polarization effects. A combination of different light scattering techniques (photon correlation, Tandem Fabry Perot and Raman spectroscopy) allows us to cover the full relevant spectral range, between 1 mHz up to about 10 THz. At the same time broadband dielectric spectroscopy (between 1 Microherz and 50 GHz) will provide information on the charge transport in the system. In that way it will be possible to unambiguously separate molecular dynamics and charge transport. The temperature dependent domain structure in the ILs will be monitored by small angle scattering techniques. Therefore, we expect to improve our understanding of the interrelation of structure formation, dynamics and charge transport in ILs and in ionogels, which, on the long run, will help to realize knowledge-based material design with ionic liquids.

离子液体（ILS），即在室温下是液体的熔融盐，是具有具有许多潜在应用的异常特性的液体，例如在所谓的“绿色化学”或能源应用中。由于其两亲性分子结构，许多离子液体倾向于在中尺度上显示自组装和结构形成（即极性和apolor结构域的形成），这会影响这些材料中的分子动力学和离子传输。当前项目的目的是了解电荷运输和分子动力学如何取决于离子液体介质结构，特别强调了这些系统中电荷传输和结构放松的耦合/解耦现象。根据分子动力学和离子传输，研究了形成极性/阿ac型结构域的不同趋势（例如，通过改变阳离子的烷基链长度或通过添加少量溶剂来实现）。在下一步中，计划在离子凝胶中调查ILS。后一种系统通过添加各种网络形成剂来基于离子液体。在这些材料中，高电导率通常与几乎固体样的机械性能相结合，这使得它们在许多应用中特别有趣。在离子凝胶中，内部表面对IL结构形成以及动力和电荷传输的影响待阐明。特别是，当网络形成代理的几何串联的长度尺度符合IL中的域和聚集体的长度范围时，预计会相交效应。就实验方法而言，当前项目的重点是去极化的动态光散射，该散射明确地识别了分子的重新定位，并且不受电荷传输或极化效应的影响。不同的光散射技术（光子相关性，串联Fabry Perot和拉曼光谱）的组合使我们能够覆盖完整的相关光谱范围，在1 MHz之间，最高约为10 THz。同时，宽带介电光谱（在1 microherz和50 GHz之间）将提供有关系统中电荷传输的信息。这样，就可以明确分离分子动力学和电荷传输。 ILS中的温度依赖性域结构将通过小角度散射技术监测。 因此，我们期望提高对ILS和离子凝胶中结构形成，动力和电荷传输相互关系的理解，从长远来看，这将有助于使用离子液体实现基于知识的材料设计。