New Syntheses of Hyperbranched Ultrathin Grafts

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This proposal will employ nonspecific molecular recognition, responsive surfaces and polyvalency to make grafting faster and more efficient. The chemistry will employ graft-on-a-graft chemistry to prepared functional, ultrathin, hyperbranched grafts on both organic and inorganic substrates. The functional interfaces to be prepared will all be assembled with covalent bonds. These covalent assemblies will be derived from known reactions - condensation reactions like amidation and catalytic reactions like triazole formation from alkynes and azides. Such grafts will contain functional groups that can be further modified with spectroscopic probes and the interfaces so formed will be useful in modification of the physical and chemical properties of common materials like polyolefins and metal oxides. The intellectual impact of this proposal is that it will demonstrate ways to use the known advantages of polyvalency, the principles of molecular recognition and the responsive character of macromolecular systems in a useful synthetic way. The proposed work will use weak intermolecular interactions like hydrogen bonding to localize reagents and catalysts at interfaces. Such localization of reagents will facilitate grafting by increasing the relative concentrations of the reagents involved in bond formation. Such effects will make grafting simpler, more practical and less wasteful in terms of reagents. If successful, this research will lead to functional surfaces can be designed so as to intelligently facilitate their own grafting. The broader impact of this proposal is its effect on the scientific training and education of students at both the undergraduate and graduate level. Typically 2-3 undergraduates from Texas A&M and outside will be involved each year, some in the summer and some during the school year. These undergraduates will work side-by-side with 2-3 graduate students. All students will have individual and creative roles in the research and all will participate in publications and presentations at local, regional and national meetings.