Synthesis, Characterization and Modification of Hyperbranched Ultrathin Grafts on Polymer Films, Fibers and Powders

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9977911BergbreiterThe chemistry in this project will lead to new methods for polymer surface modification using hyperbranched grafts. Condensation polymerization chemistry will be used to attach copolymers, dendrimers and functional colloids to carboxylic acid containing substrates. Hyperbranched grafts completely attached via carbon-carbon bonds will also be prepared using a combination of Heck and Wittig chemistry. These hyberbranched grafts will be prepared on polyolefin films, powders, colloidal particles and fibers. The resulting grafts will be designed to be responsive to pH and temperature. Further modification of the thin film interfaces formed by hyperbranched grafting will be accomplished by covalent and ionic modification chemistry. Covalent modification by "living" radial polymerization will be compared to "simple" covalent grafting on hyperbranched grafts. Ionic modification of hyperbranched grafts with polyelectolyte dendrimers, biological polymers and block copolymers will also be studied and compared with similar ionic assembly processes on neutral substrates containing monolayers of functional groups. Physical and spectroscopic studies will probe the extent of coverage of these grafts, their responsiveness to various external stimuli and their reactivity. Such studies will primarily use fluorescence, UV-visible, ESR and XPS spectroscopy. The result of these studies will be improved general synthetic routes to functional thin films on various substrates. This surface modification chemistry will lead to new methods to improve the surface properties of commonly used polymers. Such improved surface properties should lead to materials with better printability, adhesion and biocompatibility - properties that are important as existing materials are modified to be of increased utility in biotechnology and materials science.