Two Dimensional Polymerizations in Supramolecular Assemblies

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9619887 O'Brien Several methods to polymerize supramolecular assemblies have been introduced in recent years. These new and evolving chemistries open opportunities to prepare novel biomolecular materials with particular properties of interest to both biological and material sciences. Success in the design and reproducible preparation of new materials requires a clear understanding of the polymerization processes used to modify the assemblies. %%% The objective of this proposal is to advance our understanding of polymerizations in organized media in a manner that permits the utilization of the emerging information to control the properties of polymerized supramolecular materials and to prepare novel macromolecular architectures. The reasonably well-developed understanding of linear polymerizations in bilayers is complemented by the emerging picture of crosslinking polymerizations in bilayers. Polymerization of monomeric lipids in an assembly proceeds in a linear or crosslinking manner depending on the number of polymerizable groups per monomeric lipid. Lipids that contain a single reactive moiety in either of the hydrophobic tails or associated with the hydrophilic head group yield linear polymers. Polymerization of lipids with reactive groups in each hydrophobic tail yields crosslinked polymers. In contrast the polymerization of lipids that have different reactive groups (bifunctional amphiphiles) in the same hydrophobic tail does not necessarily yield crosslinked polymers, because if the groups are insufficiently separated the correlation of the polymerization paths could produce ladder polymers rather than crosslinked polymers. The preferred reaction path will depend on several factors including the nature of the spacer group, the extent of conformational and diffusional freedom within the molecular assembly, and the reactivity of the polymerizable groups. In order to obtain a clearer understanding of the effect of these factors on the preferred p olymerization process in organized media this research will examine each in turn with a family of newly designed bifunctional amphiphiles. The findings from these studies will be used to select bifunctional monomers for the preparation of ladder-like copolymers composed of dissimilar polymers, e.g. poly(diene) and poly(acrylate). The objective is to utilize our understanding of the polymerization process in organized media to create novel soluble copolymers that are not readily available through solution polymerizations. In addition these polymerization studies will aid in the design of bifunctional fatty acids for the crosslinking polymerization of monolayers or multilayers in a manner that does not modify the hydrophilic head group of the amphiphile. Finally the research will utilize the understanding of crosslinking processes in organized assemblies to prepare novel phthalocyanines for the stabilization of discotic liquid crystals. ***