CAREER: Elucidating Fundamental Structure-Property Relationships in Ionomer Nanomcomposites for Redox Flow Batteries

这项职业奖的研究目标是开发具有功能的新型纳米复合材料，这些材料可以克服大规模储能技术（如氧化还原液流电池）的实际障碍。氧化还原液流电池中使用的现有带电聚合物的离子选择性不足，促使纳米颗粒的加入，这是一种调整聚合物广泛性质的通用方法。然而，这些材料的分子尺度非均质性混淆了开发可行的液流电池纳米复合材料所需的结构-性能关系。为了解决这一差距，该职业奖的研究部分侧重于推进我们对控制功能化纳米颗粒和带电聚合物之间相互作用的基本聚合物物理学的理解，以及这些相互作用如何反过来改变与选择性离子交换相关的聚合物结构和整体功能特性。新型软复合材料的设计和合成将以这些基本的结构-性能关系为指导，以产生理想的分子尺度相互作用，从而使其具有储能应用的功能。这些发现和材料也有可能影响其他利用功能性聚合物膜的关键现代技术，如水净化和能源输送。这些研究工作与旨在吸引和激励下一代工程师和科学家的教育计划密切相关。参与该项目的本科生和研究生将接触到先进的材料合成和表征技术，使他们具备应对未来工程挑战所需的跨学科技能。与克莱姆森大学化学工程专业的学生一起，该奖项将为6-8年级的学生开发和实施一个基于stem的课外项目，该项目强调通过应用聚合物科学概念来解决科学问题，解决受现实世界挑战启发的动手任务。与研究部分一起，这些教育和推广计划旨在培养一种包容性的方法来应对STEM挑战，从而提高国家的技术和经济能力，并有助于建立一支多样化、有竞争力和创新的未来劳动力队伍。技术总结：用于氧化还原液流电池的下一代离子聚合物纳米复合材料是一种可扩展的储能技术，由于对这些带电材料中控制离子传输的潜在聚合物物理理解不足，阻碍了其设计。现有材料的复杂形态进一步混淆了基本的结构-性能关系，从而加剧了这一问题，导致迄今为止，膜性能只有微小的改善。CAREER奖的研究目标是通过研究聚合物网络结构和段动力学如何影响离子纳米复合材料的技术相关性能，来解决这一基本知识差距。这将通过系统地改变一系列含有功能化纳米颗粒的新型离子导电芳香族聚合物复合材料（例如，磺化聚芳醚酮）的分子量、单体结构和磺化程度来实现。通过调整膜的分子水平特性，以及纳米颗粒的特性（例如，表面功能化，大小和负载），可以阐明形态对膜动力学和离子传输的作用。水合复合膜的段动力学（局部运动和链动力学）将使用中子自旋回波和介电光谱进行研究，后者的实验技术也将用于表征电荷载流子的运动，即水介导的离子传输。此外，将使用红外光谱捕捉水合膜的“大规模”动力学，并与局部膜动力学进行比较。这些功能强大的非侵入性光谱技术可用于在大范围的长度和时间尺度上询问膜动力学，从而深入了解纳米颗粒特性对集体膜段动力学和离子扩散的影响。进行此类研究对于建立离子纳米复合材料的纳米尺度特征与器件相关性能之间的全面、基本关系至关重要。孔隙弹性弛豫压痕将用于表征水合纳米复合膜的力学性能和溶剂迁移动力学，因为这些直接影响水介导的离子在这些材料中的传输。随着先进功能聚合物在膜基技术中的应用不断增长，从这项研究中获得的基础知识有可能影响水净化、能量储存和输送等领域新材料的设计。该职业奖的研究部分与教育计划密切相关，该计划旨在通过教学、本科研究、推广和在当地中学实施基于STEM的课后计划，提高南卡罗来纳州北部地区STEM的多样性和包容性。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

NON-TECHNICAL SUMMARYThe research goal of this CAREER award is to develop novel nanocomposite materials with functionality that can overcome practical hurdles for large-scale energy storage technologies such as the redox flow battery. Inadequate ion selectivity in existing charged polymers utilized in redox flow batteries has motivated the incorporation of nanoparticles, a versatile approach for tuning a wide range of properties of polymers. However, the molecular-scale heterogeneity in these materials has confused structure-property relationships needed for the development of viable nanocomposite materials for flow batteries. To address this gap, the research component of this CAREER award focuses on advancing our understanding of fundamental polymer physics governing interactions between functionalized nanoparticles and charged polymers, and how these in turn alter resultant polymer architectures and bulk functional properties that are relevant for selective ion exchange. The design and synthesis of novel soft composite materials will be guided by these fundamental structure-property relationships to yield desirable molecular-scale interactions, thus enabling their functionality for energy storage applications. These findings and materials also have the potential to impact other critical modern technologies that utilize functional polymer membranes, such as water purification and energy delivery. These research efforts are closely tied to educational initiatives that aim to engage and inspire the next generation of engineers and scientists. Undergraduate and graduate students contributing to this project will be exposed to advanced materials synthesis and characterization techniques, equipping them with the interdisciplinary skills needed to address tomorrow's engineering challenges. Together with chemical engineering students at Clemson University, this award will develop and implement a STEM-based afterschool program, for students grades 6-8, that emphasizes scientific problem solving through the application of polymer science concepts to tackle hands-on tasks inspired by real-world challenges. Together with the research component, these educational and outreach programs seek to foster an inclusive approach to addressing STEM challenges that improves national technical and economic competencies, as well as helps to build a diverse, competitive, and innovative future workforce.TECHNICAL SUMMARYThe design of next-generation ionomer nanocomposites for redox flow batteries, a scalable energy storage technology, is hindered by an inadequate understanding of the underlying polymer physics governing ion transport in these charged materials. The complex morphology of existing materials exacerbates this by further confusing fundamental structure-property relationships, resulting in, to date, only marginal improvements in membrane performance. The research goal of this CAREER award is centered on addressing this fundamental knowledge gap by interrogating how polymer network structure and segmental dynamics impact technology-relevant performance properties of ionomer nanocomposites. This will be achieved by systematically varying the molecular weight, monomer architecture, and degree of sulfonation of a series of novel ion-conducting aromatic polymer composites (e.g., sulfonated poly(aryl ether ketone)s) containing functionalized nanoparticles. By tuning the molecular-level properties of the membrane, as well as the characteristics of the nanoparticles (e.g., surface functionalization, size, and loading), the role of morphology on membrane dynamics and ion transport can be elucidated. Segmental dynamics (localized motions and chain dynamics) of the hydrated composite membranes will be interrogated using both neutron spin echo and dielectric spectroscopy, where the latter experimental technique will also be used to characterize the motion of charge carriers, that is, water-mediated ion transport. In addition, 'bulk-scale' dynamics of the hydrated membranes will be captured using infrared spectroscopy and compared to the local membrane dynamics. These powerful, noninvasive spectroscopic techniques can be used to interrogate membrane dynamics over a wide range of length and time scales, providing insight into the impact of nanoparticle characteristics on the collective membrane segmental dynamics and ion diffusion. Performing such studies is critical to establishing comprehensive, fundamental relationships between nanoscale features of the ionomer nanocomposites and device-relevant performance properties. Poroelastic relaxation indentation will be employed to characterize the mechanical properties and the dynamics of solvent migration of the hydrated nanocomposite membranes, as these directly impact water-mediated ion transport in these materials. As the use of advanced functional polymers in membrane-based technologies continues to grow, the fundamental knowledge gained from this research has the potential to impact the design of new materials in areas such as water purification and energy storage and delivery. The research component of this CAREER award is closely integrated with educational initiatives that seek to improve diversity and inclusivity for STEM in the upstate South Carolina area through teaching, undergraduate research, outreach, and the implementation of a STEM-based afterschool program at a local middle school.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.