GEORGIA INSTITUTE OF TECHNOLOGY

Under the provisions of the regulations for the degree

DOCTOR OF PHILOSOPHY

on Wednesday, June 17, 2020

10:00 AM
via

BlueJeans Video Conferencing

https://bluejeans.com/609910512

DISSERTATION DEFENSE

for

Graham Parkinson

"Characterization of Aqueous Colloidal Particles via Novel Microscopies and Their Use as Structured Fluids”

Committee Members:

Prof. Paul Russo, Advisor, MSE

Prof. Karl Jacob, MSE

Prof. Mark Losego, MSE

Prof. Nicholas Hud, CHEM

Prof. Peter Yunker, PHYS

Abstract:

Aqueous colloidal particles are suspensions of solid particles within water. From milks to paints, they are a ubiquitous part of daily life. As particles in the nanometer to micron size regimes, they are uniquely positioned where their thermal energy dominates their gravitational energy yet they approach their bulk properties on the atomic scale. Characterization of these particle systems presents unique challenges as they exist on the limit for being resolved by an optical microscope. Electron microscopy and scattering techniques allow for characterization but do not allow for visualizing particle systems in situ. Liquid-phase electron microscopy and differential dynamic microscopy are two emergent techniques that allow both characterization and visualization of colloidal systems. In this work the limits on the use of differential dynamic microscopy are examined as well as its use in conjunction with liquid-phase electron microscopy. Additionally, the use of sound velocity measurements is studied as a new technique for detecting transitions within these systems. Due to their unique size range these colloidal systems can be used to both influence behavior within solution as well as serve as templates for bulk materials. Their use in reversibly inducing phase transitions in lyotropic liquid crystals via an external field is investigated. The use of an external field is also shown to effectively arrange them in order to serve as a template for bulk material systems. Positive and negative findings as well as directions for future investigations are discussed.