Date of Graduation
8-2023
Document Type
Thesis
Degree Name
Master of Science in Chemical Engineering (MSChE)
Degree Level
Graduate
Department
Chemical Engineering
Advisor/Mentor
Karthik Nayani
Committee Member
Sami Dridi
Second Committee Member
Bob Beitle
Third Committee Member
Keisha Walters
Fourth Committee Member
Samanvaya Srivastava
Keywords
Coacervates;Isothermal Titration Calorimetry;Liquid Crystals;Polyelectrolytes
Abstract
Complex coacervates are formed by liquid-liquid phase separation of an aqueous solution of oppositely charged ions. Although several mixtures of molecules of natural and synthetic macro-ion have been shown to form complex coacervates, the formation of liquid crystalline (LC) coacervates are sparsely reported. LC coacervates have a unique property in that they can change their shape and optical property in response to external stimuli such as changes in temperature, pH, or the presence of specific molecules. This property makes LC coacervates useful as a sensor, as they can be engineered to respond to specific stimuli and generate a measurable signal such as changes in texture. Here, we demonstrate the formation of liquid crystalline (LC) coacervates, achieved by the addition of very low concentrations of chromonic mesogens into solutions of polycations. We elucidate the charge-driven formation of LC-coacervates by characterizing trends in their compositions and optical textures via systematic variations in the stoichiometry and ionic strength of the solutions. Importantly, we describe an unexplored method for determining the binding stoichiometry for macromolecules using Isothermal Titration Calorimetry (ITC), and the interaction energy between the polycations. Interestingly, typical LC droplet textures are bipolar, but we observe a characteristic radial texture when the LC coacervate is viewed under cross polarized microscopy which we hypothesized is due to the orientation of the molecules within the coacervate. Overall, the unique properties of LC coacervates make them a promising area of research in the development of sensors with a wide range of applications.
Citation
Adeogun, E. (2023). Liquid Crystalline Coacervates Composed of Chromonic Mesogens and Polyelectrolytes. Graduate Theses and Dissertations Retrieved from https://scholarworks.uark.edu/etd/4872