Collaborative Research: Rational Design of Ionene + Ionic Liquid Membranes Based on Understanding Gas Transport on Different Length Scales

与传统的化学分离过程（如蒸馏和吸收）相比，膜提供了更高的能量和操作效率。然而，膜技术还没有蒸馏和吸收技术成熟。开发新的膜材料，使膜基分离与这些传统技术竞争仍然是一个重要的需求。化学分离是至关重要的，因为它们支撑着能源和材料的生产，使现代世界得以运转。改进分离过程是降低能源消耗、产品和服务成本以及温室气体（GHG）排放的关键。该项目将利用合成化学、聚合物科学、最先进的输运测量和光谱技术来开发膜结构和性能的新基础知识，这可能会导致膜性能的突破。从膜设计过程中获得的经验教训以及这些膜的结构-传输关系的发展也可以转化为其他应用，例如利用塑料废物获得新一代高性能聚合物材料的关键起始材料，这些材料具有独特的性能，可以3D打印。该项目为培养本科生和研究生各种合成和表征技术创造了机会，并利用研究者建立的现有项目来促进本科生的参与。气体扩散对聚合物膜的分离性能起着至关重要的作用。然而，对离子烯在微观（即亚微米和微米）尺度上的气体扩散的量化和基本理解，与结构不均匀性（域）的大小相当，尚未得到证明。该项目将解决这一知识缺口，在详细了解微观扩散及其与整个膜的宏观传输关系以及膜结构特性的基础上，允许合理的聚合物膜设计。协同实验研究计划的关键目标是对一种名为“双节段离子烯”（DS离子烯）的新型聚合物中的气体输运有一个基本的了解。对DS离子烯的研究将为设计用于气体分离膜的聚合物创造一个新的范例，并产生一个重要的知识体系，这也将引起分离科学和聚合物科学界的广泛兴趣。DS离子烯结构的系统变化将提供关于主要膜成分的组成、长度和体积分数如何影响所有相关长度尺度上的气体渗透性和扩散的深入知识。总体目标是了解结构-输运关系，以便定制膜成分，以最大限度地提高任何目标气体分离应用的性能。二氧化碳（CO2），甲烷（CH4）和一氧化碳（CO）气体将在微观扩散核磁共振实验中进行检查。与能源生产和消耗有关的附加气体，包括氮、氧和氢，将在宏观膜实验中考虑。该项目的成功将转化为制造用于气体分离的高渗透性和高选择性聚合物膜的能力的重大智力进步，这将是应对21世纪能源挑战所必需的。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。

Membranes offer improved energy and operational efficiency compared to traditional chemical separation processes such as distillation and absorption. However, membrane technology is less mature than distillation and absorption technologies. Developing new membrane materials to make membrane-based separations competitive with these traditional technologies remains a significant need. Chemical separations are of vital importance as they underpin the production of energy and materials that allow the modern world to function. Improvements to separation processes are key to reducing energy consumption, costs of products and services, and greenhouse gas (GHG) emissions. This project will utilize synthetic chemistry, polymer science, and state-of-the-art transport measurement and spectroscopic techniques to develop new fundamental knowledge of membrane structures and performance, which can lead to breakthroughs in membrane performance. The lessons learned through the membrane design process and the development of structure-transport relationships for these membranes can also be translated to other applications, such as utilizing plastic wastes to obtain key starting materials in the generation of new high-performance polymer materials with unique properties that can be 3D printed. This project creates opportunities for training undergraduate and graduate students in a variety of synthetic and characterization techniques and leverages existing programs established by the investigators to facilitate undergraduate student participation.Gas diffusion plays a key role in the separation performance of polymer membranes. Yet, quantification and fundamental understanding of gas diffusion on microscopic, viz. sub-micrometer and micrometer, length scales comparable with sizes of structural inhomogeneities (domains) have not been demonstrated for ionenes. This project will address this knowledge gap, allowing for rational polymer membrane design based on a detailed understanding of microscopic diffusion and its relationship with the macroscopic transport through an entire membrane as well as membrane structural properties. The key objective of the synergistic experimental research plan is to develop a fundamental understanding of gas transport in a new type of polymer named “doubly segmented ionenes” (DS ionenes). The study of DS ionenes will create a new paradigm for the design of polymers for gas separation membranes and generate a significant body of knowledge that will also be of broad interest to the separation science and polymer science communities. The systematic variation of DS ionene structures will provide deep knowledge of how the composition, length, and volume fraction of major membrane constituents influence gas permeability and diffusion on all relevant length scales. The overall goal is to develop an understanding of the structure-transport relationship that allows for tailoring membrane composition to maximize performance for any target gas separation application. Carbon dioxide (CO2), methane (CH4), and carbon monoxide (CO) gases will be examined in microscopic diffusion NMR experiments. Additional gases related to energy production and consumption, including nitrogen, oxygen, and hydrogen, will be considered in the macroscopic membrane experiments. The success of this project will translate into major intellectual advancements in the ability to build high-permeability and high-selectivity polymer membranes for gas separations, which will be required to meet the energy challenges of the 21st Century.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.