(3gu) Employing Shape As a Handle for Materials Design

The current challenge in materials design revolves around the fabrication of multifunctional materials: that is, materials exhibiting composite properties. Examples of such systems can include photonic crystals that are both mechanically and thermally active or electrolytic membranes that combines high conductivity with enhanced tensile strength. Key to achieving such materials, however, involves multi-component systems that often requires the usage of anisotropic building blocks, which dramatically enhances the potential of kinetic traps. Thus, while we currently possess an extensive library of experimentally realizable anisotropic monomers for self-assembly, we lack the requisite knowledge of how to molecularly encode building blocks interactions in a composite system to achieve our desired, target materials.

In this regard, the idea of creating chains of connected building blocks provides a potential path forward. Similar to how nature links together different sequences of the 20 amino acid building blocks to tune the resultant protein morphology while simultaneously tailoring protein activity, one can envision applying the same hierarchical strategy for our library of shaped building blocks. Here, we will specifically take advantage of the how nature enables robust control over both protein form and function by encoding molecular interactions through the sequence with which they are bonded together. For us, each individual building block takes on the role of an “amino acid” and the self-assembled morphologies for these chains of connected shapes are the resulting “proteins” of interest. In other words, the goal is to answer the overarching question of: can we program interactions into chains of anisotropic monomers in such a way that drives them to spontaneously “fold” into controlled, targeted morphologies at desired conditions? Thus, I aim to create a theoretical framework to a priori define ways with which we can encode self-assembly interactions directly into sequences with which we build chain of anisotropic building blocks so as to drive them to fold into targeted morphologies exhibiting the desired, macroscopic properties. Specifically, I will employ a combination of polymer scaling and mean-field theory to extend our current knowledge of how building block geometry influences local behaviors of a given system to the case of chains of connected anisotropic particles. Once a rigorous understanding of these local effects is established, similar extensions will be made employing theories of polymer dynamics to connect to macroscopic properties such as diffusion constant, conductivity, and tensile strength. The resultant composite framework can then serve as a predictive tool to design sequences of building blocks that can direct chain folding into a suite of novel structures, providing a computationally guided testing ground for future experiments.

Teaching Interest

My primary philosophy in regard to teaching revolves about the central idea of helping students acquire a fundamental understanding of the materials while simultaneously providing them with ways to develop the relevant skills required to become an effective professional or researcher in their respective field. With regard to lecturing, I believe that this will be best achieved through a combination of step-by-step explanations of key concepts -- grounded with real-world examples -- and ``lab'' sessions where students are asked to apply concepts towards a more complex problem in a guided environment. In terms of mentoring, I believe that each graduate student necessitates his or her own uniquely tailored mentoring strategy that requires periodic adjustments to fit the current needs. As a result, my approach will be more flexible, by design, in order to account for their individual needs. I believe weekly one-on-one meetings with students to discuss both research results and direction will not only provide a good way to learn about each student’s strengths, but also serve to highlight areas that could benefit from more guidance. Ultimately, my goal aims to help students build the proper fundamentals groundwork through helping them understand materials at a fundamental level and then training them to be proficient with the skills necessary to apply that fundamental knowledge to real-world problems.

Publications

1). Babji Srinivasan, Thi Vo, Yugang Zhang, Oleg Gang, Sanat Kumar, Venkat Venkatasubramanian. “Designing DNAgrafted particles that self-assemble into desired crystalline structures using the genetic algorithm.” PNAS, 2013, 110.

2). Thi Vo, Venkat Venkatasubramanian, Sanat Kumar, Babji Srinivasan, Suchetan Pal, Yugang Zhang, Oleg Gang. “Stoichiometric control of DNA-grafted colloid self-assembly.” PNAS, 2015, 112.

3). Yugang Zhang, Suchetan Pal, Babji Srinivasan, Thi Vo, Sanat Kumar, Oleg Gang. “Selective transformations between nanoparticle superlattices via the reprogramming of DNA-mediated interactions.” Nature Materials, 2015, 14.

4). Fang Lu, Thi Vo, Yugang Zhang, Alex Frenkel, Kevin G. Yager, Sanat Kumar, Oleg Gang. “Unusual Packing of Soft-Shelled Nanocubes,” Science Advances, 2019, 5. [co-first author]

5). Thi Vo and Sharon Glotzer. “Principle of corresponding states for hard polyhedron fluids,” Molecular Physics, 2019, 117.

6). Katherine C. Elbert, Thi Vo, Nadia M. Krook, William Zygmunt, Jungmi Park, Kevin G. Yager, Russell J. Composto, Sharon C. Glotzer. “Dendrimer ligand directed nanoplate assembly,” ACS Nano, 2019, 13. [co-first author]

7). Ye Tian, Julien Lhermitte, Lin Bai, Thi Vo, Huolin Xin, Ruipeng Li, Masafumi Fukuto, Kevin Yager, Sanat Kumar, Oleg Gang. “Ordered three-dimensional nanomaterials using DNA-prescribed and valence-controlled material voxels,” Nature Materials, 2020, https://doi.org/10.1038/s41563-019-0550-x.