(371c) Structure/Property Relationships in Polymer Membranes for Water Purification and Energy Applications

Providing sustainable supplies of purified water and energy is a critical global challenge for the future, and polymer membranes will play a key role in addressing these clear and pressing global needs for water and energy. Polymer membrane-based processes dominate the desalination market because they are more energy efficient than thermal desalination processes, and polymer membranes are crucial components in several rapidly developing power generation and storage applications that rely on membranes to control rates of water and/or ion transport. Much remains unknown about the influence of polymer structure on even basic intrinsic water and ion transport properties, and these relationships must be developed to design next generation polymer membrane materials. For desalination applications, polymers with simultaneously high water permeability and low salt permeability are desirable in order to prepare selective membranes that can efficiently desalinate water, and a tradeoff relationship between water/salt selectivity and water permeability suggests that attempts to prepare such materials should rely on approaches that do more than simply vary polymer free volume. One strategy is to functionalize hydrocarbon polymers with fixed charge groups, e.g., sulfonate groups, that can ionize upon exposure to water, and this seminar discusses the influence of polymer charge on transport properties. Additionally, in electric potential field-driven applications, the performance of anion exchange membranes (AEMs), containing positively charged functional groups, such as quaternary ammonium moieties, lags behind that of cation exchange membranes, containing tethered negative charges such as sulfonate groups. Improved AEMs are needed to optimize and extend technologies such as electrodialysis and reverse electrodialysis, and processes that rely on thermolytic salts, such as ammonium bicarbonate, will require polymer membranes optimized for those ions. This seminar presents an overview of research aimed at further understanding fundamental structure/property relationships that govern water and ion transport in ion containing polymer films considered for desalination and electric potential field-driven applications that can help address global needs for clean water and energy.