Date of Graduation
5-2025
Document Type
Dissertation
Degree Name
Doctor of Philosophy in Engineering (PhD)
Degree Level
Graduate
Department
Chemical Engineering
Advisor/Mentor
Nayani, Karthik
Committee Member
Beitle, Robert R. Jr.
Second Committee Member
Dridi, Sami
Third Committee Member
Srivastava, Samanvaya
Fourth Committee Member
Monroe, Jacob
Fifth Committee Member
Walters, Keisha B.
Keywords
Biopolymers; Coacervates; Colloids; Liquid crystals; Phase separation
Abstract
Liquid-liquid crystalline phase separation (LLCPS) is an intricate phenomenon observed in the presence of LC-forming molecule governed by intricate molecular interactions and thermodynamic forces. LLCPS manifests as the demixing of a solution into two distinct phases: a dense phase enriched with LC-forming components coexisting with a supernatant phase depleted in LC content. In this study, we highlight the interplay between lyotropic chromonic liquid crystals (LCLCs) and other rod-like molecules, leading to LLCPS. We note that the phase separation can be associative or segregative. Associative phase separation, more commonly known as complex coacervation, arises due to an attractive interaction such as charge-based interactions, hydrogen bonding, hydrophobic interactions, and π-π interactions between two molecules. The basic form of LC coacervation consists of an LC-forming molecule and an oppositely charged polyelectrolyte. Here, the dense (coacervate phase) consists of the LC-forming molecule and the polyelectrolyte, while the supernatant is mostly water. We uncover surprising LC coacervate droplets with sensitive and unique optical properties that can be influenced by external stimuli. We exploit chiral LCLCs – induced by chiral molecules dopants to explore the role of chirality in the type of complex formed (isotropic or nematic). The primary mechanism that drives segregative LLCPS is the entropic depletion force, which arises when large particles are placed in a solution of smaller ones and sterically constrained to avoid them. Existing studies have however largely focused on understanding LLCPS from the lens of the participating polymers/particles being spherical/isotropic, rather than rod-shaped, despite the prevalence of rod-shaped biopolymers participating in LLCPS in vivo. We harnessed the LLCPS phenomena of rod-shaped particles to eventuate the development of biosensors for DNA. We emphasize that the biosensing mechanism and/or the sensitivity achieved with rod-shaped particles is unattainable with their spherical counterparts.
Citation
Adeogun, E. (2025). Liquid-Liquid Crystal Phase Separation in Solutions of Binary Rod-like Systems. Graduate Theses and Dissertations Retrieved from https://scholarworks.uark.edu/etd/5715
