(6hn) Understanding and Controlling Self-Assembly in Polymer and Colloidal Systems through Simulation, Theory, and Experiment

Functional polymer materials play a central role in a vast array of fields, ranging from polymer nanocomposites for aerospace materials, to electron and ion-conducting polymers for electronics and energy, to biocompatible polymers for drug delivery. To satisfy performance metrics in these myriad applications, diverse new polymer chemistries, architectures, assembly paradigms, and processing schemes are constantly being developed. However, controlling the complex interplay between equilibrium driving forces and kinetic limitations in polymer and colloidal self-assembly, though crucial to appropriately harnessing these new techniques, remains a challenge. My independent research program will address this gap by predicting the equilibrium structure of new functional polymer and colloidal systems and uncovering how to use processing techniques, additives, or chemical modifications to shift the equilibrium state and/or manipulate assembly kinetics to trap useful nanoscale and microscale structures. My group will employ a unique combination of molecular simulation and theory techniques supported by key experimental characterization. This combined simulation/theory/experiment approach will allow me to efficiently interrogate the molecular-level phenomena behind soft materials assembly, enabling the design of optimized processes and strategies to navigate the structure/function pipeline of materials development.

In my Ph.D. research with Prof. Arthi Jayaraman, I used a combination of molecular simulation, theory, and scattering techniques to study a variety of synthetic and bioinspired soft materials systems—this experience forms the basis of my future research program. From a computational methodology standpoint, I leveraged statistical thermodynamics to develop new Gibbs ensemble simulation methods (6) to enable efficient study of the phase equilibria of polymer solutions, and I also contributed an open-source Python implementation of the Polymer Reference Interaction Site Model (PRISM) theory (1,9). Using these techniques, I investigated the structure and thermodynamics of polymer solutions of varying architecture (linear, cyclic, star) (2,11) and connected intramolecular structure to intermolecular assembly in films and dense solutions (2). In another effort, I developed simulation methods to study the colloidal self-assembly of bioinspired photonic materials in evaporative thin-film and reverse emulsion assembly processes (10). Using these techniques, I uncovered key physical insights that helped explain the structure of the photonic assemblies and clarified the differences between the film and emulsion techniques. My simulation and theory expertise is complemented by my experience performing experiments in Prof. Thomas Epps’s lab, where I used neutron and x-ray scattering to study lithium salt-doped block polymer materials for battery electrolytes (3,4), rationalizing the self-assembly of the salt-doped block polymers through comparison to molecular simulations and strong segregation theory. In each project I pursued a holistic understanding of the phenomena that control the structure and thermodynamics of polymer and colloidal materials by combining simulation, theory, and experiment. Furthermore, I successfully engaged in a diverse set of working styles, ranging from simulation-only projects to joint efforts with 1-2 experimental collaborators, to large multi-institution collaborations that connected multiple materials synthesis, characterization, and computational groups. Prior to graduate school I worked for three years in industrial R&D in semiconductor manufacturing, in which I received recognition for my creative research contributions—from this industry experience I learned how to design and pursue industrially-relevant and applications-oriented research. As a faculty member I will leverage this diversity of methodological and topical expertise from my academic and professional background to enrich and strengthen my independent research program.

My future research will focus on three key areas: 1) macromolecular design and architecture, 2) dynamic non-covalent bonding and supramolecular assembly, and 3) 'alchemical' transformations in polymer and colloidal systems. I will pursue these topics with an emphasis on applications in optical and electronic materials, nanotemplating and patterning, and drug delivery, areas where precisely tunable self-assembly, dynamic responses to the environment, and switchable structure and functionality are crucial. Manipulating polymer architecture is a longstanding technique to tune phenomena ranging from self-assembly to macroscopic material properties, and new advances in polymer synthesis have greatly expanded the available library of architectures to attain new states, structures, and functionalities. Supramolecular self-assembly is a rich area for new materials development, as the dynamic nature of non-covalent bonding provides valuable characteristics like fast assembly, self-healing capabilities, and 'smart' responsiveness to environmental and/or actuated triggers. Furthermore, modulating soft materials assembly through 'alchemical' transformations in polymer chemistry and/or architecture is an emerging field that can produce unexplored non-equilibrium or metastable structures, and unlocks new paradigms in switchability of structure and function. In my research on each of these topics I will synergistically apply molecular simulation and PRISM theory to quickly screen parameter spaces and provide mechanistic insights, while validating model development and key conclusions through comparison to scattering experiments. In parallel, I will also develop and leverage non-equilibrium simulation techniques to guide the design of polymer processing schemes. This combined computation/theory/scattering research framework will help direct synthetic efforts and enable improved process and materials design, furthering the development of new functional polymer materials solutions for photonics, medicine, nanomaterials technology, and energy.

Teaching Interests:

I consider effective teaching to be of equal importance to innovative research, as I believe that impactful faculty-student interactions can have wide-reaching effects in fostering an informed and interested cohort of future scientists, engineers, and policymakers. As a faculty member I am excited to act on my commitment to teaching by creatively connecting students' classroom work to the world around them via tangible and relatable examples, assignments, and projects. In my teaching I plan to draw from my hybrid academic and professional background to foster interest in academic research while maintaining an eye on the industrial relevance of the subject matter. When explaining key concepts, I will draw from the diversity of career paths and research interests within chemical engineering to help foster curiosity and engagement in my students.

My formal teaching background centers around experiences as a teaching assistant for courses in thermodynamics and polymer science and engineering; in both courses I delivered lectures, hosted office hours and review sessions, and fielded individual questions from students. I have also tutored an undergraduate student in thermodynamics, fluid mechanics, heat and mass transfer, and chemical kinetics. Though my varied research, teaching, and professional background has prepared me to teach several core chemical engineering subjects, I am particularly interested in thermodynamics at the undergraduate and graduate level. Through my teaching assistantship experience I gained a keen appreciation for the challenges and sticking points for students when approaching key concepts in thermodynamics—for example, choosing from the myriad available activity coefficient models in phase equilibria calculations. In my thermodynamics curriculum I hope to clarify the process of problem-solving, to help students navigate available methodological choices and develop an appropriate problem-solving workflow. In addition, I am interested in developing courses in polymer physics, statistical thermodynamics, and molecular simulation and theory with a polymer and/or soft materials focus to help train the next generation of soft materials scientists.

Publications (7 current publications, 4 additional in preparation or review):

1. T.B. Martin, T.E. Gartner, III, R.L. Jones, C.R. Snyder, A. Jayaraman, "pyPRISM: a computational tool for liquid-state theory calculations of macromolecular materials," Macromolecules, 2018, 51(8), 2906–2922
2. T.E. Gartner, III, A. Jayaraman, "Macromolecular 'size' and 'hardness' drives structure in solvent-swollen blends of linear, cyclic, and star polymers," Soft Matter, 2018, 14, 411-423
3. T.E. Gartner, III,* M.A. Morris,* C.K. Shelton,* J.A. Dura, T.H. Epps, III, "Quantifying lithium salt and polymer density distributions in nanostructured ion-conducting block polymers," Macromolecules, 2018, 51 (5), 1917-1926; *Equal contributions
4. T.E. Gartner, III, T. Kubo, Y. Seo, M. Tansky, L.M. Hall, B.S. Sumerlin, T.H. Epps, III, "Domain spacing and composition profile behavior in salt-doped cyclic vs linear block polymer thin films: a joint experimental and simulation study," Macromolecules, 2017, 50 (18), 7169-7176
5. M.A. Morris,* T.E. Gartner, III,* T.H. Epps, III, "Tuning block polymer structure, properties, and processability for the design of efficient nanostructured materials systems,"** Macromol. Chem. Phys., 2017, 218 (5), 1600513; *Equal contributions; **Cover article
6. T.E. Gartner, III, T.H. Epps, III, A. Jayaraman, "Leveraging Gibbs ensemble molecular dynamics and hybrid Monte Carlo/molecular dynamics for efficient study of phase equilibria," J. Chem. Theory Comput., 2016, 12 (11), 5501-5510
7. H. Wu, H. Pan, M.A. Green, D. Dietderich, T.E. Gartner, III, H.C. Higley, M. Mentink, D.G. Tam, F.Y. Xu, F. Trillaud, X.K. Liu, L. Wang, and S.X. Zheng, "The resistance and strength of soft solder splices between conductors in MICE coils," IEEE Trans. Applied Superconductivity, 2011, 21 (3), 1738-1741

In Preparation or Review:

8. H. Kuang, T.E. Gartner, III, A. Jayaraman, E. Kokkoli, "Controlling the Length and Diameter of DNA Nanotubes Formed by ssDNA-Amphiphiles," Submitted to ACS Appl. Nano Mater. (in revision)
9. T.B. Martin, T.E. Gartner, III, R.L. Jones, C.R. Snyder, A. Jayaraman, "Design and Implementation of pyPRISM: A Polymer Liquid-State Theory Framework," Submitted to Proceedings of the 17th Python in Science Conference. (in review)
10. M. Xiao,* T.E. Gartner, III,* Z. Hu,* X.Yang, W. Li, A. Jayaraman, N.C. Gianneschi, M.D. Shawkey, A. Dhinojwala, "Surface segregation of binary particles in photonic supraballs and films," *Equal contributions (in preparation)
11. T.E. Gartner, III, M.J.A. Hore, A. Jayaraman, "Solvent quality effects on the thermodynamics and scaling of linear and cyclic polymer solutions," (in preparation)