Intermolecular Interactions And Applications Of Supercritical CO 2 Fluoroepoxy Oligomers

Supercritical carbon dioxide (scCO2) is increasingly accepted as a nontoxic, nonflammable, easily recyclable and environmentally benign medium. Its solvability or solvation power can be adjusted by altering the pressure and/or temperature without changing the composition of the system, and importantly, the products can be efficiently separated via decompression. Hence, scCO2 is available to be applied in the fields such as homogeneous catalysis or the extraction of noble metals instead of traditional organic solvents, in which the challenge of poor reuse or recycle of catalysts is expected to be distinctly improved. While simultaneously, the barrier in the application of scCO2 has also been clearly confirmed as its nonpolarity and the resulted inability to effectively solvate the majority of polar compounds, macromolecules, chelating ligands and catalysts. It is shown that if the targeted ligands/complexes/catalysts are transplanted or grafted by proper solubilizing chains, their solubility in scCO2 will be expectantly enhanced. Therefore, much attention has been paid to explore solubilizing chains for scCO2 system. While the intermolecular-interaction in scCO2 is considered to be the theoretical foundation for the select/design of efficient solubilizing chains. By investigating the intermolecular interactions, the solvation behaviors of certain category of dispersates and their dominated solubility of the dispersates in scCO2 system can be evaluated. Hence, designing or selecting superior solubilizing chains is expected to provide desirable/fundamental insight into the research and application of scCO2 technology.The present thesis mainly focuses on 3 contents as follows:(1) Preparation and characterization of the model epoxide oligomers.Three categories of 14 epoxide oligomers, namely polyethylene oxide with two acetyl groups (PEO-Ac2), polypropylene oxide with two acetyl groups (PPO-Ac2) and fluorinated epoxide oligomers (PHFPO or FEO), were intentionally designed and synthesized. The targeted oligomers were characterized via NMR and FT-IR. The results identified and confirmed that the oligomers were successfully obtained.(2) Monitoring the intermolecular-interaction dominated solvation processes of the epoxide oligomer+CO2 systemsThe detailed solvation behaviors of the epoxide oligomers in gaseous and supercritical CO2 were investigated by using a set of HP ATR FTIR. The main factors impacting on the intermolecular-interactions between the epoxide oligomers and CO2 were systematically discerned and evaluated. The ideal and efficient solubilizing chain which was appropriate for SCCO2 system was selected based on the results of the solvation behaviors. The results show that it is the synergistic effects of the undermining/decreasing of the cohesion(or the self-interaction) among FEO molecules deriving from such fluorine repulsion and -CF3, the excellent accessibility of FEO to CO2 and the increased special attraction between FEO and CO2 predominantly enhance the solubility of FEO in SCCO2. Based on such congnition, FEO is suggested to be the most soluble species in SCCO2 and may thus act as the ideal solubilizing chain after being transplanted or grafted into some targeted chelating ligands, complexes or polymers.(3) Exploration of the preparation and characterization of Ir-catalyst with fluorinated chelating ligandsIn order to perform or achieve the homogeneous catalysis in the environmentally benign medium of scCO2 as well as the reuse or recycle of the catalysts, the cyclometalated iridium complex was synthesized and intentionally modified with the selected solubilizing chain (FEO). The obtained novel iridium complex was well characterized and confirmed via 1 NMR, which is expected to be capable of the catalyst for the CDH in scCO2 system.