Synthesis of fluorinated segment containing oligomers for supercritical carbon dioxide applications
Bilgin, Nalan (2003) Synthesis of fluorinated segment containing oligomers for supercritical carbon dioxide applications. [Thesis]
Two types of fluorinated block containing oligomers were synthesized and utilized as surfactant systems for supercritical carbon dioxide (CO) applications. Solubility experiments with the prepared oligomers were performed using a pressure-temperature controllable supercritical CO device. The experiment was designed in three steps. First, acylchloride ended di-functional azo initiator was synthesized from its acidic derivative. Then two types of fluorinated azo initiators were synthesized by esterification of the acylchloride groups through the reaction with two different fluoroalcohols in the presence of phase catalyst. The fluoroalcohols differed mainly in their end group character: While one's end group carbon was completely fluorinated, the other contained an extra hydrogen atom in this group. The final and the main step of the experiment consisted of the synthesis of fluorinated tri-block oligomers. Several commercially available monomers were reacted with the fluoroinitiators through radical polymerization mechanism. With the two types of initiators two sets of oligomers were obtained. The obtained oligomer blocks were tri-blocks consisting of monomer repeating groups with fluorinated side segments. Materials were characterized with infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (H NMR, C NMR, and F NMR), and thermal analyses (DSC, TG/DTA) Solubilities of the two oligomer series were tested in supercritical CO. The effects of end group nature, chain fluorination degree and chemical structure (intermolecular interactions) on solubility efficiency were investigated. Solubility is largely affected by the end group nature of the fluorinated segments and the intermolecular interactions occurring between the oligomers and the supercritical phase. Initial findings will be studied in details.
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