Synthesis of hollow core-shell polymer particles and the synthesis of phosphate fluorosurfactants for use in carbon dioxide.

摘要

This work has been divided into two distinct parts, with the first part discussing the synthesis of hollow core-shell particles. The design of the synthesis involves the use of sequential emulsion polymerization steps and the polyelectrolyte effect to produce the hollow core-shell morphology. Emulsion copolymerization of 2-vinylpyridine (2VP) with styrene is being used for the synthesis of a swellable core. In an acidic environment, 2VP can protonate to form a polyelectrolyte. Methyl methacrylate, a high Tg material, is then being used for encapsulating the swollen seed particle, and retention of the original composite particle diameter. As the pH is neutralized, the swollen core decreases in size with the deprotonation of the amine functionality. This leaves a void between the polymer layers, leading to hollow particles. Two different tacks were explored in these studies, and these were surfactant-free emulsion polymerizations and surfactant-based polymerizations. Data and results towards the synthesis of hollow core-shell particles using each of these techniques will be discussed.; The second part of this work details the background of surfactants that have been used to form water-in-CO2 microemulsions. The need for surfactants to form assemblies, such as emulsions or microemulsions, within CO2 to uptake water is key to developing a process for use in microelectronics cleaning and drying. Previous work has shown that fluorinated phosphate surfactants are able to uptake water into CO2 through the formation of water-in-CO 2 microemulsions. In order to make these surfactants more compatible, the synthesis of anionic phosphate-based surfactants with one partially fluorinated chain and one fully hydrocarbon chain, as well as two partially fluorinated chains, using ammonium, tetramethylammonium, and calcium counterions have been studied. Solution behavior was assessed for each of these surfactants alone in CO2, as well as ternary systems also containing water. Additionally, as there is a driving force towards the use of non-fluorinated materials as a surfactant, due to low feasibility, the synthesis and solubility of hydrocarbon analogs to the fluorinated materials were studied. It was found that having a branched hydrocarbon surfactant was capable of sustaining a carbon dioxide in water emulsion. These results will also be presented.