(2lk) Processing-Structure-Property Relationships for Anisotropic Soft Materials

From electronics to healthcare, soft materials promise to fundamentally change modern technology. Advances in fields such as organic electronics, bioelectronics, and energy storage require continuous discovery of materials that exhibit anisotropic structure. My research interest is in discovery of new anisotropic soft materials through the directed self-assembly and solidification of liquid crystals. The materials discovered in my lab would be of interest for additive manufacturing, sensing, and organic electronics. To develop new processing techniques to control the structure of liquid crystalline materials my research group will build upon my experience in nanofabrication, vacuum deposition, and microfluidics. To evaluate the degree of ordering in the newly discovered soft materials, my group will leverage my expertise in scattering techniques.

The overarching theme of my research has been the structure and dynamics at the interfaces of soft materials. In my undergraduate research, I performed molecular dynamics simulations of the interface of insulin and water. In my PhD I used synchrotron x-ray scattering to conduct the first quantitative studies of the structure of vapor-deposited glassy organic semiconductors at interfaces. These studies revealed the mechanism of structure formation at interfaces of vapor-deposited glasses; structure at the interface is intimately linked to device performance. These papers are particularly technologically relevant as vapor deposition is the industry standard to form the 500 million OLED (organic light emitting diode) displays manufactured annually. In my postdoc, I used chemo-epitaxy to prepare single crystals of blue-phase liquid crystals (BPLCs). The single-crystals assembled on nano-patterned surfaces were polymerized using UV-radiation. BPLCs are soft photonic crystals which are of broad interest for sensing and display applications. My work helped determine a strategy to overcome the key shortcomings limiting the applicability of BPCLs: polycrystallinity and thermal instability.

My future research interests fall into the following categories: 1) Harnessing liquid crystallinity to prepare macroscopically organized solids for sensing, organic electronics, and soft robotics. 2) Studying molecular orientation of emissive dopants in liquid crystal solvents for organic LED applications and 3) studying liquid crystals in microfluidic flow for 3D printing applications. The overarching theme of my research will be harnessing liquid crystallinity to prepare functional polymeric and soft materials. Liquid crystals enable control of structure over macroscopic distances which is important for technological applications. Macroscopic control of structure can also enable formulation of structure-property relations in soft materials. The physics of liquid crystals is intimately connected to interactions and energetics at surfaces. My training in interfacial science therefore positions me well to explore phenomenon in liquid crystals.

Teaching Interests:

I am interested in teaching undergraduate and graduate level courses for the following topics: 1)Thermodynamics 2) Interface Science and Engineering and 3) Soft Condensed Matter. During my PhD at UW-Madison, I was a teaching assistant for undergraduate thermodynamics courses. I have taken thermodynamics courses at both chemistry and engineering departments. As an educator, I will combine my experiences of being a thermodynamics student at different departments to provide my students a broader perspective on the field. 8 years of research experience positions me well to teach courses in Interface Science and Engineering and Soft Matter. I am interested in developing an elective course for graduate and advanced undergraduate students called “Soft matter physics for non-physicists”. The course would be designed to introduce fundamental concepts in the field of soft matter to graduate and advanced undergraduate chemical engineering, material science, biophysics, and chemistry students. The course would cover polymers, surfactants, liquid crystals, and biomolecules, with an emphasis on modern technological and medical applications of these materials.

Undergraduate Research:

My lab will provide opportunities for undergraduate students to perform and publish independent research. My research interests involve liquid crystals, which can be researched using benchtop optical microscopes. Short term projects will be designed for undergraduate students involving optical microscopy and liquid crystals. The completion of these projects will lead to first author publications for undergraduate researchers. I believe research should be an important component of undergraduate education, and my lab will be well placed to support undergraduate researchers.

Selected Publications:

1) Emeršič., T*., Bagchi, K*., Martínez-González, J.A ., Li, X ., de Pablo, J.J ., and Nealey, P. F. 2022. A Generalizable Approach to Direct the Self-Assembly of Functional Blue-Phase Liquid Crystals. Advanced Functional Materials. *=Contributed Equally. https://doi.org/10.1002/adfm.202202721

2) Fiori, M.E*., Bagchi, K*., Toney, M.F. and Ediger, M.D., 2021. Surface equilibration mechanism controls the molecular packing of glassy molecular semiconductors at organic interfaces. Proceedings of the National Academy of Sciences.*=Contributed Equally. https://doi.org/10.1073/pnas.2111988118

3) Bagchi, K., Deng, C., Bishop, C., Li, Y., Jackson, N.E., Yu, L., Toney, M.F., de Pablo, J.J. and Ediger, M.D., 2020. Over what length scale does an inorganic substrate perturb the structure of a glassy organic semiconductor?. ACS Applied Materials & Interfaces. https://doi.org/10.1021/acsami.0c06428

4) Bagchi, K., Jackson, N.E., Gujral, A., Huang, C., Toney, M.F., Yu, L., de Pablo, J.J. and Ediger, M.D., 2018. Origin of Anisotropic Molecular Packing in Vapor-Deposited Alq3 Glasses. The journal of physical chemistry letters. https://doi.org/10.1021/acs.jpclett.8b03582

5) Bagchi, K. and Roy, S., 2014. Sensitivity of water dynamics to biologically significant surfaces of monomeric insulin: Role of topology and electrostatic interactions. The Journal of Physical Chemistry B. https://doi.org/10.1021/jp411136w

Grants:

Co-authored renewal of US Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, Award DESC0002161.