(4lw) Rational Design of Polymers for Sustainable Water, Energy, and Environmental Separations

My academic interests are at the nexus of polymer science, materials engineering, and separations. Specifically, my research program will focus on establishing a fundamental understanding of the molecular factors that govern thermodynamics and transport across polymer-solution interfaces. These physical phenomena are the foundation of technologies that rely on chemical separations to address humanity’s need for clean water and sustainable energy (e.g., water purification, resource recovery, electrolysis, fuel cells, and batteries). Inherent linkages between water and energy require disruptive advancements in the economics of these technologies. Due to their energy efficiency and modular nature, polymer membranes are attractive materials for water and energy relevant systems. However, many of the molecular interactions that underpin membrane performance (e.g., throughput and separation efficiency) are poorly understood, hindering rational design of high-performance membranes. My group will utilize a multifaced approach, combining synthesis, material characterization, and theoretical modeling to develop predictive frameworks that quantify solute and solvent transport rates as a function of polymer structure and solution properties. Structure-property relationships developed from these fundamental studies will enable design of new materials having precisely tailored transport properties.

Research Experience:

My expertise in membrane science and polymer physics uniquely positions me to lead this effort. As a Ph.D. student at UT Austin, I investigated ion and water transport in swollen polymer membranes under the guidance of Prof. Benny Freeman, with an extensive focus on experimental characterization of state-of-the-art ion exchange membranes. I uncovered, for the first time, the role of ion dissociation on ion sorption in hydrated membranes. Using this insight, I developed a theoretical model to predict salt partitioning more broadly in charged polymers, which is critical for interpreting ion selectivity in membrane-based processes. Furthermore, I led a foundational study that demonstrated that hydraulic water transport in ion exchange membranes occurs via a diffusion mechanism, which resolved a topic of significant debate in this community. Beyond conventional membranes, I also studied novel polymers to design cation specific selectivity, a property required in lithium recovery processes that eludes current membranes. By pursuing a collaboration with groups specializing in synthesis and computational methods, we developed materials with the highest Li⁺/Na⁺ permeability selectivity ever reported in hydrated polymers. In my current position as a postdoctoral scholar at UCSB, I am working alongside Prof. Rachel Segalman to systematically study ionic conductivity and water sorption in polymer electrolytes exposed to controlled humidity. My work in this area has established a critical link between rigorously dry and highly swollen polymers by unraveling how various hydration-based phenomena (e.g., ion solvation and polymer plasticization) influence ion transport rates in materials relevant to the polymer physics and membrane science communities. Leading this cross-fertilization of ideas will enable breakthroughs in materials design for advanced separations.

Teaching Interests:

My passion for patiently teaching and mentoring the next generation of scientists and engineers in an environment that promotes diversity, equity, and inclusion drives my pursuit of an academic position. Throughout my career, I have followed this passion by pursuing various teaching and mentorship opportunities, beginning with my time as an undergraduate at Rensselaer Polytechnic Institute, where I worked as a tutor for physics and chemical engineering courses. In this position, I led open class sessions twice a week, where I developed and presented instructional material to convey core scientific concepts to a diverse group of students. During my graduate studies at UT Austin, I served as a teaching assistant for both undergraduate (Mass and Energy Balances) and graduate (Mass Transport in Polymers) courses, where I designed exam problems and regularly prepared and delivered large class lectures.

In addition to traditional coursework, I have also mentored numerous high school, undergraduate, and graduate students through various research projects and outreach opportunities. Helping students from a broad range of backgrounds has been especially rewarding and has given me firsthand experience with the importance of teaching others with compassion and encouraging underrepresented students to pursue STEM disciplines. My education and experience have prepared me well to teach any core chemical engineering courses as a faculty member. Specifically, I am interested in teaching Transport Phenomena, Thermodynamics, Mass and Energy Balances, and Separations, and would be excited to develop graduate coursework related to my expertise (e.g., Thermodynamics of Electrolyte Systems and Transport Phenomena in Polymeric Materials).

Selected Publications (*denotes equal contribution):

1. R. Sujanani, K.K. Reimund, K.L. Gleason, and B.D. Freeman, “Hydraulic Permeation-Induced Water Concentration Gradients in Ion Exchange Membranes”, Journal of Membrane Science, 705, 122858, (2024), https://doi.org/10.1016/j.memsci.2024.122858
2. R. Sujanani*, O. Nordness*, A. Miranda, L.E. Katz, J.F. Brennecke, and B.D. Freeman, “Accounting for Ion Pairing Effects on Sulfate Salt Sorption in Cation Exchange Membranes”, Journal of Physical Chemistry B, 127, 8, 1842-1855, (2023), https://doi.org/10.1021/acs.jpcb.2c07900
3. P. Aydogan Gokturk, R. Sujanani, J. Qian, Y. Wang, L.E. Katz, B.D. Freeman, and E.J. Crumlin, “The Donnan Potential Revealed”, Nature Communications, 13, 5880, (2022), https://doi.org/10.1038/s41467-022-33592-3
4. R. Sujanani, L.E. Katz, D.R. Paul, and B.D. Freeman, “Aqueous Ion Partitioning in Nafion: Applicability of Manning’s Counter-ion Condensation Theory”, Journal of Membrane Science, 638, 119687, (2021), https://doi.org/10.1016/j.memsci.2021.119687
5. S.J. Warnock*, R. Sujanani*, E.S. Zofchak*, S. Zhao, T.J. Dilenschneider, K.G. Hanson, S. Mukherjee, V. Ganesan, B.D. Freeman, M. Abu-Omar, and C.M. Bates, “Engineering Li/Na Selectivity in 12-Crown-4 Functionalized Membranes”, Proceedings of the National Academy of Sciences of the United States of America, 118, 37, e2022197118, (2021), https://doi.org/10.1073/pnas.2022197118
6. M. Allen*, R. Sujanani*, A. Chamseddine, B.D. Freeman, and Z.A. Page, “Mechanically Robust Hydrophobized Double Network Hydrogels and Their Fundamental Salt Transport Properties”, Journal of Polymer Science, 59, 2581-2589, (2021), https://doi.org/10.1002/pol.20210260
7. R. Sujanani, M.R. Landsman, S. Jiao, J.D. Moon, M.S. Shell, D.F. Lawler, L.E. Katz, and B.D. Freeman, “Designing Solute-Tailored Selectivity in Membranes: Perspectives for Water Reuse and Resource Recovery”, ACS Macro Letters, 9, 11, 1709-1717, (2020), https://doi.org/10.1021/acsmacrolett.0c00710