(2gs) Sequence-Defined Polymers for Precise Engineering of Assemblies and Interfaces Towards Responsive Soft Materials

Nature provides rich inspiration for designing highly sophisticated structures that dynamically respond to environmental stimuli, where the primary determinant of biological structures and functionalities takes place at the atomic/monomer level. Recent advances in polymer synthetic chemistry have enabled sequence-definition beyond the realm of biopolymers, expanding our capabilities to make increasingly precise and complex synthetic polymers. The accompanied vast chemical and architectural parameter space with synthetic sequence-defined polymers grant us great opportunities, as well as challenges, to rationally design, predict, and access complex structures and functionalities across multiple length scales in soft materials.

I envision my independent research program to build upon my expertise in fundamental polymer physics and sequence-defined polymer design, to create assemblies and interfaces with precise, finely-tuned responsiveness and functional group distribution with monomer-level control. We will leverage a new polymer platform based on bioinspired, sequence-defined polypeptoids made via solid-phase-synthesis, which embraces both the robustness of synthetic polymers and the precision of biopolymers. We will harvest the breadth of available functional handles enabled by various conjugation strategies to precisely place stimuli-responsive moieties and/or specific binding sites along the (co)polymer chains. Designing polymers with monomer-level control will allow us to tailor intra- and intermolecular interactions to target properties that uniquely emerge from sequence-definition, such as precision assemblies and phase separations driven by secondary structures and charge distributions. My future research program will advance our fundamental understandings of structure–property relationships with monomer-level insights, and develop polymer-based systems with precisely tunable responsiveness for drug delivery and sensor applications. We also seek inspiration from biophysics to provide new perspectives, and opportunities to bridge synthetic sequence-defined polymers with biopolymers.

Research Experience

Ph.D. Dissertation: Polypeptoid Chain Conformation and Its Role in Block Copolymer Self-Assembly
Advisor: Prof. Rachel Segalman
Department of Chemical Engineering, University of California, Santa Barbara
Dec 2016 – Mar 2021

Postdoctoral Research: Biological Pathways towards Single-Digit Nanofabrication
Advisors: Dr. Ricardo Ruiz, Dr. Ronald Zuckermann
Molecular Foundry, Lawrence Berkeley National Laboratory
Mar 2021 – present

My research has been dedicated to molecular design of polymers, nanoscale self-assembly, and integrating multi-length scale interactions towards building hierarchical structures. During my Ph.D., I focused on the fundamental polymer physics of how non-ideal chain shapes impact self-assembly, by incorporating bioinspired sequence-defined polymers, polypeptoids, into block copolymers. I determined the difference in thermodynamic contributions caused by a helical secondary structure, and demonstrated minimal chain conformation difference at the interface drives different morphologies of block copolymers, finding preferrable designs to access complex network phases. As a postdoctoral researcher, I expanded into more interdisciplinary fields designing semiconductor/bio interfaces, where I am developing molecularly designed, sequence-defined polymer brushes to create surface guiding patterns for directing the assembly of biomolecular building blocks, to achieve nanopatterning with registration and long-range order. My research training in polymer physics and synthesis, advanced characterization with an emphasis on light/X-ray/neutron scattering, and nanofabrication establishes my firm roots in polymer science, and makes me uniquely suited to work at the interface of polymer science, nanotechnology, and biomaterials to advance my proposed research program.

Teaching Interests

In addition to establishing a world-class research program, teaching and mentoring have always been parts of an academic career I am excited about. The chief philosophy of my teaching and mentoring is to train undergraduate and graduate students as ethical, technically strong chemical engineers and scientists, and to motivate students to explore topics of interest in related fields with knowledge and skill sets equipped. As a graduate student at UC Santa Barbara, I have gained experiences as teaching assistant for courses including “Chemical Engineering Laboratory Lab Sessions”, “Non-Newtonian Fluids, Soft Materials and Chemical Products”, and “Analytical Methods in Chemical Engineering”. The courses vary in distinct ways in terms of instruction format, deliverables of coursework, and technical skill emphasis. My teaching experience covers experimental design and supervision, class demonstrations, recitation lectures and office hours.

With my chemical engineering background and teaching experiences, I am comfortable teaching chemical engineering core courses including thermodynamics, transport, kinetics and reaction engineering at both undergraduate and graduate levels. In addition, as a trained polymer scientist through my graduate and postdoctoral research, I would be excited to teach and/or develop courses in polymer science and engineering at the undergraduate level, and polymer physics, polymer chemistry, advanced characterization techniques at the graduate level.

Selected Publications (4 of 10)

[1] Yu, B.; Li, R.; Segalman, R. A. Tuning the Double Gyroid Phase Window in Block Copolymers via Polymer Chain Conformation Near the Interface. Macromolecules 2021, 54 (12), 5388-5396.

[2] Yu, B.; Danielsen, S. P. O.; Yang, K.-C.; Ho, R.-H.; Walker, L. M.; Segalman, R. A. Insensitivity of Sterically Defined Helical Chain Conformations to Solvent Quality in Dilute Solution. ACS Macro Lett. 2020, 9, 849-854.

[3] Patterson, A. L.; Yu, B.; Danielsen, S. P. O.; Davidson, E. C.; Fredrickson, G. H.; Segalman, R. A. Monomer Sequence Effects on Interfacial Width and Mixing in Self-Assembled Diblock Copolymers. Macromolecules 2020, 53(9), 3262-3272.

[4] Yu, B.; Danielsen, S. P. O.; Patterson, A. L.; Davidson, E. C.; Segalman, R. A. Effects of Helical Chain Shape on Lamellae-Forming Block Copolymer Self-Assembly. Macromolecules 2019, 52 (6), 2560-2568.