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http://hdl.handle.net/11375/6215
Title: | Designing Hydrogel Microspheres from Liquid-Liquid Phase Transitions of Aqueous Polymer Solutions |
Authors: | Yin, Xiangchun |
Advisor: | Stover, Harald D. |
Department: | Chemistry |
Keywords: | Chemistry;Chemistry |
Publication Date: | May-2004 |
Abstract: | <p>This thesis focuses on reactive water-soluble polymers suitable for forming liquid-liquid phase transitions from both polyelectrolyte complexation and thermal induction. Novel hydrogel microspheres are formed by liquid-liquid phase transition followed by crosslinking reactions. Besides studying the properties of polymers and hydrogel microspheres formed, the mechanism of liquid-liquid phase transitions as well as potential applications of these systems in protein separation and encapsulation are discussed. Chapter 1 describes the background of liquid-liquid phase transitions of aqueous polymer solutions, including polyelectrolyte complexation, thermally nduced phase transition and their application in designing hydrogel microspheres. Chapter 2 describes the thermo-responsive properties of fully MPEG-grafted maleic anhydride copolymers in aqueous solutions. The phase transitions are ascribed to the cooperative effects of intra/intermolecular hydrogen bonding and hydrophobic interactions. Chapter 3 describes the use of analogous partially MPEG-grafted maleic anhydride copolymers as reactive polyanions to form phase-separated liquid polyelectrolyte complexes with polycations, and to prepare hydrogel micro spheres by crosslinking the polyelectrolyte complexes with polyamines. Chapter 4 and Chapter 5 extend this two-stage approach of liquid-liquid phase transition followed by crosslinking reaction to thermally induced phase transitions. Thermally induced liquid-liquid phase transitions of poly(N,N-dimethacrylamide-coglycidyl methacrylate) and poly(N,N-dimethylacrylamide-co-allyl methacrylate) aqueous solutions are thus used to prepare hydrogel microspheres. The morphology of the resulting micro spheres is studied by electron microscopy. The mechanism of thermally induced liquid-liquid phase transitions ofpoly(N,Ndimethacrylamide) copolymer solutions is discussed in Chapter 6, together with the preparation of well-defined model copolymers using atom transfer radical polymerization.</p> |
URI: | http://hdl.handle.net/11375/6215 |
Identifier: | opendissertations/1542 2151 1261207 |
Appears in Collections: | Open Access Dissertations and Theses |
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fulltext.pdf | 6.56 MB | Adobe PDF | View/Open |
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