(7hs) Tailoring Functionality from Disorder : Complex Nonequilibrium Phenomena at Biological and Nanomaterial Interfaces

Materials design is at the forefront of pioneering technology to address some of our most challenging global issues. One notable direction has been to leverage unique behavior that arises at the interface of dissimilar material constituents and phases, e.g., nanomaterials, complex fluids, and soft condensed materials. The additional interactions at these interfaces typically induce molecular structuring that deviates from the characteristic disorder found in bulk counterparts. Intriguingly, such subtle microscopic changes tend to propagate to macroscopic changes in material properties. Furthermore, the use of external forces, such as mechanical strain or electrical bias, introduce a dynamic means of tuning interfacial phenomena. Hence, identifying the key molecular mechanisms at play, which can span multiple length and time scales, will facilitate the design of hybrid materials with tailored functionality. To pursue this goal, I am particularly interested in (1) understanding the principles used by biological building blocks (i.e., proteins, lipids, and nucleic acids) to regulate cellular processes and (2) adapting these principles to create functionally diverse nanomaterials. Given the crowded environment within cells, it is fascinating that many concurrent yet distinct biological activities proceed with high specificity. I anticipate that the fundamental structure-function relationships and mechanisms that regulate these inherently dynamic processes can be leveraged toward materials design in applications including energy storage and conversion, drug targeting and delivery, and water purification. To this end, I envision a research program that utilizes my extensive background in multiscale computational simulations and unites my interests in nanotechnology, biophysics, and sustainability.

Successful Proposals: Ruth L. Kirschstein National Research Service Award (NIH F32)

Postdoctoral Project: “Multiscale Simulations of HIV-1 Assembly, Budding, and Maturation” under the supervision of Gregory A. Voth, Department of Chemistry, Institute for Biophysical Dynamics, James Franck Institute, The University of Chicago

PhD Dissertation: “First-Principles Investigation of Carbon-Based Nanomaterials for Supercapacitors” under the supervision of Gyeong S. Hwang, McKetta Department of Chemical Engineering, The University of Texas at Austin

Research Experiences:

My training, which has been highly interdisciplinary, has culminated in a hierarchical computational skillset that ranges from nano- to micro-scales. As a graduate student, I developed a combined quantum mechanical and classical molecular dynamics framework to study low-dimensional material interfaces. I primarily focused on understanding charge storage mechanisms at the interface of carbon nanomaterials and ionic liquid electrolytes for supercapacitor applications. As a postdoctoral scholar, I am now extending my expertise in atomistic simulations with coarse-graining (CG) theory and enhanced sampling techniques. In my present work, I am utilizing CG approaches to investigate viral assembly and budding at cell membrane interfaces to discover new avenues for anti-viral treatment. I have also had the benefit of many fruitful collaborations with my experimental colleagues, especially through my participation in ARPA-E, NSF and NIH-funded interdisciplinary centers. Through these connections, I have been privileged to engage with experts that have broadened by scientific perspectives and have allowed me to explore new directions for my research. I am confident that these comprehensive experiences will enable me to address unique scientific questions at the interface of synthetic materials and biology.

Teaching Interests:

Throughout my education and early career, my mentors have been invaluable for my growth as an independent scientist and engineer. As a faculty member, I eagerly look forward to my responsibility as a mentor and teacher for the next generation of young scientists. My core teaching philosophy can be described by three tenets. My foremost goal is to instill a passion for learning by fostering the curiosity and confidence to be inquisitive without fearing failure. One of my most rewarding experiences has been to design interactive activities that highlighted interesting concepts in nanotechnology and computational research, which I further showcased to local students ranging from elementary to high school levels. My second goal is to create tangible connections between what students learn in academic settings and real-world problems. For this reason, I firmly believe in the value of immersive, project-based learning as a supplement to lectures. Not only do these projects help translate engineering skills toward problem solving, but also help establish communication and collaborative skills. During my undergraduate studies, I appreciated the value of such courses, one of which eventually inspired me to pursue computational research in graduate school. Finally, I hope to create an environment for my students to practice a critical-thinking mindset, e.g., to question underlying assumptions and to develop physical intuitions. In my experience as a teaching assistant (for undergraduate courses on fluid mechanics and computational methods), I regularly held recitation sessions with time allocated to stimulate such discussions; many of my students have told me that they found this approach refreshing and helpful for understanding the material. I plan to continue to evolve my teaching philosophy during my academic career. While I am prepared to teach any course, I am most interested in fluid mechanics, thermodynamics, or numerical methods. I am also looking forward to developing new courses based on my core competencies, such as a broad introduction to the growing field of computational sciences.

Selected Publications:

1. A. J. Pak, J. M. A. Grime, P. Sengupta, A. K. Chen, A. E. P. Durumeric, A. Srivastava, M. Yeager, J. A. G. Briggs, J. Lippincott-Schwartz, G. A. Voth, “Immature HIV-1 lattice assembly dynamics are regulated by scaffolding from nucleic acid and the plasma membrane,” under review (2017).
2. A. J. Pak and G.S. Hwang, “Molecular insights into the complex relationship between capacitance and pore morphology in nanoporous carbon-based supercapacitors,” ACS Appl. Mater. Interfaces, 8 (2016), 34659-34667.
3. W. Wei, L. Chang, K. Sun, A. J. Pak, E. Paek, G. S. Hwang, Y. H. Hu, “The bright future for electrode materials of energy devices: Highly conductive porous Na-embedded carbon,” Nano Lett., 16 (2016), 8029-8033.
4. A. J. Pak and G. S. Hwang, “Charging rate dependence on ion migration and stagnation in ionic liquid-filled carbon nanopores,” J. Phys. Chem. C, 120 (2016), 24560-24567.
5. A. J. Pak and G. S. Hwang, “Theoretical analysis of thermal transport in graphene supported on hexagonal boron nitride: The importance of strong adhesion due to p-bond polarization,” Phys. Rev. Appl., 6 (2016), 034015.
6. D. Wu*, A. J. Pak*, Y. Liu, X. Wu, Y. Ren, Y. Zhou, Y. Tsai, M. Lin, H. Peng, G. S. Hwang, and K. Lai, “Thickness-dependent dielectric constant of few-layer In2Se3 nano-flakes,” Nano Lett., 15 (2015), 8136-8140.
7. A. J. Pak, E. Paek, and G. S. Hwang, “Impact of graphene edges on enhancing the performance of electrochemical double layer capacitors,” J. Phys. Chem. C, 118 (2014), 21770-21777.
8. A. J. Pak, E. Paek, and G. S. Hwang, “Tailoring the performance of graphene-based supercapacitors using topological defects: a theoretical assessment,” Carbon, 68 (2014), 734-741.
9. E. Paek, A. J. Pak, and G. S. Hwang, “A computational study of the interfacial structure and capacitance of graphene in [BMIM][PF6] ionic liquid,” J. Electrochem. Soc., 160 (2013), A1-A10.

^* indicates co-first authorship

Full list can be found in my Google Scholar profile (https://scholar.google.com/citations?user=J19dfCQAAAAJ&hl=en)