Research
Nature serves as a rich source of inspiration for molecular materials design. Our research team focuses on biomimetic, bioinspired, and bioderived polymers (B3P), broadly defined. We develop innovative synthetic methods to produce well-defined polymers and conduct fundamental studies to understand the structure-property-function relationships of polymers and polymer solutions relevant to a range of materials applications. Students involved in this research will gain valuable skills in polymer synthesis and develop proficiency in a variety of analytical techniques for characterizing polymers and macromolecular solutions.
We are seeking motivated graduate students, undergraduate students, and postdoctoral researchers to join our research team. If you are interested in exploring research opportunities in our lab, please contact our PI, Donghui Zhang, directly for more information about current openings. Below are some of the key research directions we are currently pursuing.
- Understanding the Role of Charge Patterning in Aqueous Assembly of Sequence-Defined
Polymers. Charge patterning—defined by the specific positioning and number of ionizable monomers
along chain-like molecules—has gained recognition as a crucial factor in modulating
the chain conformation, inter-chain interactions, and phase behavior of biological
molecules, such as intrinsically disordered proteins and polysaccharides. However,
the potential of charge patterning to control the conformation and solution self-assembly
of non-biological polymers remains largely unexplored and not well understood. In
this study, we use sequence-defined peptoid polymers as a synthetic model system,
leveraging the precise sequence control and chemical diversity made possible by sub-monomer
synthesis. This approach allows us to establish heuristic design principles for creating
peptidomimetic soft colloids, providing new insights into the effects of charge patterning
and guiding the development of advanced, tunable polymer-based materials.
- Controlling Hierarchical Assemblies of Polypeptoid Polymers through Crystallization-Driven
Self-Assembly. Polypeptoid polymers, with N-substituted polyglycine backbones, form a class of
pseudo-peptidic polymers with a strong tendency to crystallize into a cubic lattice.
The dimensions of this lattice’s unit cell can be precisely tuned by adjusting molecular
characteristics of the polypeptoid, such as the degree of polymerization and N-substituent
sidechain structure. In this study, we explore the crystallization-driven self-assembly
of polypeptoid block copolymers in solution, yielding hierarchical nanostructures
with well-defined geometry, size, and internal organization. An important aspect of
the study is to characterize and understand how variations in self-assembly conditions
influence the mechanisms and pathways of assembly, leading to morphological differences
in the resulting nanostructures. Collaborators: Prof. Naisheng Jiang (USTB).
- Dissipative Assembly of Polymer-Grafted Particles for Self-Healing Materials. Microcrack formation and propagation in polymer composites can result in catastrophic
material failure. In this project, we investigate an external field-driven approach
using polymer-grafted particles as a versatile strategy to repair microcracks at the
onset of their formation. Nano- and microparticles can assemble into superstructures
with diverse configurations under the influence of external electric or magnetic fields.
These assemblies are transient, dynamic, and reconfigurable. By grafting polymers
onto particle surfaces, we can effectively tailor the range and nature of particle
interactions, enabling controlled, field-driven assembly. In this study, we explore
the assembly behavior of polymer-grafted particles under a magnetic field and develop
chemical strategies to stabilize the superstructures formed in these assemblies. Collaborators:
Prof. Bhuvnesh Bharti (LSU), Prof. Andrew Peters (LaTech) and Prof. Noshir Pesika
(Tulane).
- Liquid-Liquid Phase Separation of Peptidomimetic Polymers. Liquid-liquid phase separation (LLPS) is a phenomenon commonly observed in solutions
of oppositely charged polyelectrolytes or polyampholytes, resulting in the coexistence
of a polymer-rich phase and a polymer-dilute phase. Electrostatic interactions are
often considered the primary drivers of LLPS in these charged macromolecules. However,
the role of non-electrostatic interactions in influencing the thermodynamics of LLPS
remains less understood. In this study, we aim to investigate how non-electrostatic
interactions contribute to the thermodynamic landscape of LLPS in peptidomimetic polymers,
offering insights into additional mechanisms that govern phase separation behavior.
Collaborator: Prof. Whitney Blocher McTigue (Lehigh).
- The Chemistry-to-Biology Transition in the Origin of Life. The Miller-Urey experiment famously demonstrated the formation of amino acids under conditions thought to resemble those of early Earth. Since then, research has shown that a variety of small molecules, such as peptides and RNA, can form under plausible prebiotic conditions. These molecules typically have short chain lengths of fewer than ten monomer units. A critical question in understanding the transition from chemistry to biology is how these short-chain peptides or RNA molecules could grow longer and develop meaningful sequences. For instance, a 20-amino-acid peptide composed of randomly selected prebiotic amino acids would yield an extensive library of 1120 unique sequences, making the spontaneous formation of functional sequences improbable. This vast sequence space suggests that a dynamic mechanism must have existed to facilitate chain elongation and selectively enrich specific sequences. In this study, we experimentally investigate the fundamental aspects of the foldmer-catalyst model, a framework that may explain the chemistry-to-biology transition. Collaborator: Prof. Ken Dill (SBU) and Dr. Ron Zuckermann (LBNL).