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Research
Our research aims to understand and engineer the dynamics of complex fluids, focusing on systems containing polymers, colloids, active matter, and combinations of these components.
Complex Fluids
Squishy polymer assembly
Spherical and squishy domains of polymer aggregates deform and produce regular structures when they are squeezed into a denser arrangement. This observation is related to the crystallization of materials from liquid states. Understanding how these regular structures vary with the characteristics of the polymers and processing conditions will help us design materials with desired properties.
Polymer brush coatings
Coatings of brush polymers undergo conformational changes when subjected to different environments. Depending on the solvent quality, the polymer coating will be more swollen or more compact, which affects the internal structure. Correlating the two can shed a light on the relationship between structure and performance of polymer-functionalized materials.
A wrinkle in space
With Prof. Amir Hirsa, we are examining protein aggregation in flow in microgravity (on the International Space Station). During removal of the material, the interface wrinkles in space, highlighting the non-Newtonian mechanical properties of the gelled protein surface film. Understanding how proteins aggregate in flow and near surfaces will help us understand natural phenomena within some diseases and processes during pharmaceutical manufacturing.
Field theory of interacting particles
Field theory models simulate the behavior of concentrations of particles instead of individual particles. This type of coarse-grained modeling allows us to sample larger time and length scales, while still relating microscopic interactions to the macroscopic behavior. One important application is phase separation, where a kymograph quantifies the onset of structure. In some applications such as drug delivery, phase separation should be avoided. While for other applications such as precipitation purification, phase separation is the desired outcome.
Stochastic field theory for polymers
Many field theory models represent an average behavior at equilibrium. Stochastic field theories can be used to quantify the fluctuations in dynamics out of equilibrium. But they had only previously been applied to particle suspensions. We have generalized the approach to systems with conformational degrees of freedom. For example, fluctuating polymer concentrations must capture both positions and stretch. This approach allows the simulation of dynamics of assembly of complex polymeric fluids.
Polymers in shear flow
When a polymer is subjected to shear flow, it experiences deformation due to the application of external forces. We use coarse-grained Brownian dynamics simulations to explore how polymer topology (such as linear, ring, and star) influences rheological behavior. This is crucial for predicting and designing polymer-based materials with desired properties.
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