Structure and Dynamics of Soft Matter

软物质的结构和动力学

• 批准号: RGPIN-2017-03938
• 负责人: Frisken, Barbara
• 金额: $ 3.06万
• 依托单位: Simon Fraser University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=762459
• 关键词: Structure; Dynamics; Soft; Matter

With this Discovery Grant, I will study the morphology of ion-conducting polymers, with the long-term goal of improving material properties of polymer electrolyte membranes (PEMs) for fuel-cell applications. Good proton conductivity in PEMs depends on polymer morphology and ionic nanostructure. Controlling this morphology is essential to the design of high-performance membranes. These experiments will contribute to the fundamental understanding necessary to optimize polymer design for these applications, and ultimately aid our transition to a low-carbon society. These studies will address current challenges in PEM research: to reduce emphasis on fluorine-based polymers through development of robust hydrocarbon-based ionomers, to improve polymer lifetime, and to improve durability. One focus will be a series of hydrocarbon-based, proton-conducting polymers designed to offer an alternative to fluorine-based systems. This material is a random copolymer but early studies show some phase separation at nm length scales; we will study the morphology to determine the nature of the phases and inform the next generation of these polymers. My research group and I will also study a new hydrocarbon-based, anion-conducting random copolymer, designed for use in alkaline fuel cells where the alkaline environment allows for the use of much cheaper catalysts. Our recent studies show no evidence of ion-clustering and indicate that water is distributed at sub-nm length scales; we will elucidate conductivity mechanisms. Finally, this research will contribute to understanding polymer lifespans through studies of degradation of Nafion, the polymer most commonly used in fuel cell applications. In particular, we will study how the morphology changes during standard degradation tests.The main experimental methods that we use are based on scattering of radiation from materials. My research group now has access to a wide range of length scales through light-scattering instruments in my lab (small-angle and classic, length scales from 10 microns to 20 nm) and a recently installed small-angle X-ray scattering instrument in Simon Fraser University's materials facility (length scales from 20 nm to 0.2 nm). We also use neutron scattering to provide complementary information. These tools allow us to study a wide range of behaviour: aggregation of polymer molecules, micro-phase separation, ion-clustering, polymer backbone ordering, and order at the monomer level. Recently, we have successfully used molecular dynamics simulations to complement our measurements at the smallest length scales and plan to continue to develop this capability.

借助这笔发现补助金，我将研究离子导电聚合物的形态，长期目标是改善燃料电池应用的聚合物电解质膜（PEM）的材料性能。 PEM 中良好的质子电导率取决于聚合物形态和离子纳米结构。控制这种形态对于高性能膜的设计至关重要。这些实验将有助于对优化这些应用的聚合物设计所需的基本理解做出贡献，并最终帮助我们向低碳社会过渡。这些研究将解决当前质子交换膜研究中的挑战：通过开发坚固的烃基离聚物来减少对氟基聚合物的重视，提高聚合物的使用寿命，并提高耐用性。其中一个重点是一系列碳氢化合物基质子传导聚合物，旨在提供氟基系统的替代品。这种材料是一种无规共聚物，但早期研究表明在纳米长度尺度上存在一些相分离；我们将研究形态以确定相的性质并为下一代这些聚合物提供信息。我和我的研究小组还将研究一种新的碳氢化合物基阴离子传导无规共聚物，设计用于碱性燃料电池，其中碱性环境允许使用更便宜的催化剂。我们最近的研究没有显示离子簇的证据，并表明水分布在亚纳米长度尺度；我们将阐明导电机制。最后，这项研究将通过研究燃料电池应用中最常用的聚合物 Nafion 的降解，有助于了解聚合物的寿命。特别是，我们将研究标准降解测试期间形态如何变化。我们使用的主要实验方法基于材料的辐射散射。我的研究小组现在可以通过我实验室的光散射仪器（小角度和经典，长度尺度从 10 微米到 20 nm）以及最近安装的小角度 X 射线散射仪器来获得各种长度尺度。西蒙弗雷泽大学的材料设施（长度范围从 20 nm 到 0.2 nm）。我们还使用中子散射来提供补充信息。这些工具使我们能够研究广泛的行为：聚合物分子的聚集、微相分离、离子簇、聚合物主链排序以及单体水平的排序。最近，我们成功地使用分子动力学模拟来补充我们在最小长度尺度上的测量，并计划继续开发这种能力。