Amidine-based switchable surfactants can be used as stabilizers during emulsion polymerization and the resulting latexes can then be destabilized by the removal of CO2. High Tg polymers have been successfully redispersed, as shown by recovery of primary particle size (measured by light scattering methods), but an input of energy was required. Sonication was the first method used, but lower-energy methods such as rotor-stators and a blender have also been successful in redispersing aggregated latexes. Colloidal stability was found to be reversible for at least three aggregation/redispersion cycles, and redispersibility was retained after the removal of water and addition of fresh water. Stimuli-responsive polymer colloids with reversible colloidal stability may have many uses. The shipping of latexes, for example, would be easier and less energy intensive if the latex particles could be aggregated and the bulk of the water removed. The latexes would then have to be redispersed prior to use.
Switchable surfactants have also been used for the semi-continuous copolymerization of butyl acrylate and methyl methacrylate to form a high solids content (42 wt%), low-Tg latex. The latex can be destabilized with air and heat but cannot undergo redispersion because the low Tg polymer particles fuse upon aggregation. The copolymer, when dried at room temperature, formed a continuous film. Latexes with high solids content and low Tg’s are representative of latex paint formulations. Because the switchable surfactants have been shown to be successful in preparing these latexes, it is possible that they may be useful in the latex paint industry, for example as fast setting paints. / Thesis (Master, Chemistry) -- Queen's University, 2011-09-26 13:18:33.905
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:OKQ.1974/6755 |
| Date | 26 September 2011 |
| Creators | O'NEILL, CATHERINE |
| Contributors | Queen's University (Kingston, Ont.). Theses (Queen's University (Kingston, Ont.)) |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English, English |
| Detected Language | English |
| Type | Thesis |
| Rights | This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner. |
| Relation | Canadian theses |
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