(4gz) Soft Materials for Membrane Separations for Water, Energy, and the Environment

Research challenges and opportunities

Opportunities are numerous for advanced soft materials to tackle Grand Challenges for Engineering through supplying clean energy, addressing climate change, promoting sustainability, and ensuring resource and water security. Gas- and solvent-selective polymer membranes are attractive tools for carbon capture and energy efficient production and purification of hydrocarbon resources. Chemically-patterned polymer membranes and adsorbents also offer promise as fit-for-purpose treatment of wastewater, potentially enabling removal of recalcitrant contaminants such as perfluoroalkyl substances (PFAS).

Addressing water, energy, and environmental separation challenges with soft materials requires marriage of innovative material design with a fundamental understanding of the interplay between molecular diffusion, thermodynamics, and polymer physics. Major challenges still face separation technologies that rely on soft materials, such as the detrimental effects of plasticization on membrane selectivity and mechanical properties as well as poor selectivity of conventional adsorbents for challenging solutes such as PFAS.

PhD and post-doctoral research

In my PhD research with Profs. Benny Freeman and Donald Paul at UT Austin, I demonstrated that gas diffusion in nonequilibrium, glassy polymers plasticized by water vapor involves a complex interplay between fractional free volume and chain mobility, resulting in significant effects on membrane selectivity.^1-3 We further identified a method of improving H₂/CO₂ separation performance of these materials through synergistic polymer blending and thermal-rearrangement, resulting in performance exceeding the current day upper bound.^4-5

To develop my synthetic expertise and broaden my research background, I pursued a collaborative post-doctoral program with Profs. Rachel Segalman and Craig Hawker at UC Santa Barbara where, in a series of cross-disciplinary projects, I developed a versatile synthetic platform for synthesizing polymer hydrogels decorated with a wide array of ligands, including basic, acidic, solute-chelating, and EPR-active moieties.⁶ Bio-inspired metal-ligand chelation has been found to improve toughness and fracture resistance in these hydrogels by a hundred-fold, and control over network chemistry and structure afforded by our synthetic approach enables elucidation of the interplay between water and ion transport and polymer functionality. I also investigated the interrelations between macroscale and molecular-scale water dynamics in polymer solutions through a unique collaboration that combined new EPR-based experimental tools with diffusion NMR and molecular dynamics simulations.

Future research goals

My independent research program will aim to use functional soft materials to address major water, energy, and environmental challenges in chemical engineering by intersecting polymer chemistry, polymer physics, and membrane science.

Key areas of experimental study will cover:

• Applying versatile polymer synthesis to developing membrane materials for carbon capture, energy-efficient gas and solvent separations, and water treatment
• Understanding thermodynamics, transport phenomena, and polymer physics in swollen or plasticized polymers and in glassy polymers far from equilibrium
• Tailoring mechanical performance of polymer membranes and other soft materials through bio-inspired dynamic chemistries

Teaching Interests

Due to my chemical engineering background and teaching experience, I am qualified to teach core undergraduate and graduate chemical engineering courses. Particular courses I would be eager to teach include thermodynamics, transport phenomena, mass and heat transfer, mass and energy balances, and introductory polymer science and engineering. I would also be excited to develop graduate elective courses centered around mass transfer in polymers, drawing on my multifaceted experience working with experts in the areas of polymer membranes, polymer electrolytes, and polymer physics. In addition to serving as a TA for both undergraduate and graduate courses at UT Austin, I also completed an engineering TA certification program and took two graduate elective courses on Teaching Engineering and Engineering Curriculum Design.

My teaching philosophy draws on a Socratic method to progress students from factual knowledge to critical and creative thinking and finally to effective communication. To promote diversity, equity, and inclusion, my pedagogy seeks to incorporate inclusive language and use course material that is accessible to students from various backgrounds while also helping disadvantaged students find tutors and mentoring opportunities to help them succeed. In undergraduate and graduate research, supportive mentorship and collaboration is crucial both for students’ success and for coming up with creative solutions to engineering challenges. I will actively seek to foster a culture of collaboration, inclusion, and mentorship among junior and senior students in my research group.

Selected Publications

1. Moon, J. D.; Galizia, M.; Borjigin, H.; Liu, R.; Riffle, J. S.; Freeman, B. D.; Paul, D. R., Water vapor sorption, diffusion, and dilation in polybenzimidazoles. Macromolecules 2018, 51 (18), 7197-7208.

2. Moon, J. D.; Galizia, M.; Borjigin, H.; Liu, R.; Riffle, J. S.; Freeman, B. D.; Paul, D. R., Modeling water diffusion in polybenzimidazole membranes using partial immobilization and free volume theory. Polymer 2020, 189, 122170.

3. Moon, J. D.; Borjigin, H.; Liu, R.; Joseph, R. M.; Riffle, J. S.; Freeman, B. D.; Paul, D. R., Impact of humidity on gas transport in polybenzimidazole membranes. Journal of Membrane Science 2021, In review.

4. Freeman, B. D.; Paul, D. R.; Moon, J. D. Thermally-rearranged polymer blends for gas separation membranes. US Patent Application No. 17/044,540, 2019.

5. Moon, J. D.; Bridge, A. T.; D'Ambra, C.; Freeman, B. D.; Paul, D. R., Gas separation properties of polybenzimidazole/thermally-rearranged polymer blends. Journal of Membrane Science 2019, 582, 182-193.

6. Moon, J. D.; Sujanani, R.; Geng, Z.; Freeman, B. D.; Segalman, R. A.; Hawker, C. J., Versatile synthetic platform for polymer membrane libraries using functional networks. Macromolecules 2021, 54 (2), 866-873.