AdvisorO'Brien, David F.
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PublisherThe University of Arizona.
RightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
AbstractSupramolecular assemblies are composed of noncovalently associated molecules which organize in water to yield 2-D and 3-D architectures. Crosslinking polymerization of supramolecular assemblies provides an effective means to modify their chemical and physical properties. Two methods of characterizing crosslinked polymeric assemblies were developed. These techniques rely on experimentally observed changes in polymer solubility and assembly stability in the presence of nonionic surfactants. The results show an inefficient crosslinking mechanism in organized media compared to isotropic polymerization. Two models rationalizing the inefficient crosslinking observed in organized media were proposed. Symmetrical crosslinking agents were synthesized to test the models. These results suggest intramolecular memorialization is an important process in the efficiency of crosslinking. The polymerization of a heterobifunctional lipid with two polymerizable groups in the same acyl chain separated by a six carbon spacer yielded a novel linear ladder-like polymer architecture. The two reactive groups are in regions of different polarity allowing for the simultaneous, selective, and sequential polymerization depending on the initiation chemistry employed. A second heterobifunctional lipid was designed and synthesized with a longer spacer between the two reactive groups. Polymerization of vesicles gave stable polymeric vesicles. The results from the crosslinking and redox polymerization studies on 2-D assemblies were applied to the inverted hexagonal and bicontinuous cubic phases. Phase behavior is characterized before and after crosslinking polymerization principally by variable temperature ³¹NMR. γ-Initiated polymerization of bis-lipids was studied to evaluate their sensitivity to ionizing radiation. The reactive moiety effects the initial rate of polymerization, extent of polymerization, and inhibition by oxygen. A preliminary investigation of polymerizable ion-paired amphiphiles (IPA) showed polymerization methods commonly used for zwitterionic lipids can be applied to IPA. This is the first report of polymerization of reactive groups in the anionic acyl chain of an ion-paired amphiphile.
Degree ProgramGraduate College