On the behavior of complex systems dissolved in carbon dioxide

Supercritical CO₂ has emerged as an environmentally friendly alternative to organic liquid solvents due to its unique characteristics and tunability, which allow for its diverse utility. However, an expansion of molecular-level knowledge is needed to further target and tailor its application as an extraction, separation, processing, and/or reaction medium. This dissertation focuses on a quantitative assessment of complex systems in CO₂ by investigation of the fluorescence of a probe at the end of a flexible solute or the inherent absorbance of a reaction product. Three main areas are investigated: (1) polymer dynamics and conformational changes as a function of CO ₂ density, added cosolvent, or CO₂ added to a liquid solvent to provide fundamental information pertinent to the application of CO ₂ as a tunable solvent for polymer processing and synthesis, (2) the use of CO₂ as a tunable reaction media and the effect of CO ₂ density on reaction pathways, and (3) the use of reverse micelles formed in CO₂ as a media for enzymatic synthesis of specialty pharmaceutical compounds. This presentation will touch briefly on each of these areas focusing mainly on polymer dynamics in neat and cosolvent modified CO₂.