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

University Of Florida, Gainesville FL

Investigators

Abstract

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.