The focus of this research is three fold. First, azo and perester containing bi- and tri-functional free-radical initiators will be synthesized and examined as precursors to star polymers, and block copolymers containing functional groups at the block interfaces. Second, the radical chemistry of molecules containing an azoxy group will be examined with a specific emphasis on determining, depending on the position of azoxy group, the mechanisms of intramolecular cyclization and ethylene evolution. Lastly, the mechanism by which halogens form complexes with azoalkanes and 1,2-dialkylhydrazines will be elucidated and the radical chemistry of the resulting adduct examined. Graduate and postdoctoral students will be introduced to the free radical chemistry of the aforementioned organic molecules, and free radical polymerization. With this award, the Organic and Macromolecular Chemistry Program supports the research and educational activities of Dr. Paul Engel of the Department of Chemistry at Rice University. Dr. Engel will focus his research on the synthesis and characterization of organic molecules containing two or more azo or perester groups. Activating these groups with either heat or light leads to highly reactive sites referred to as free radicals. By positioning the azo or perester groups within the molecule, and thereby defining the sites at which the free radicals are generated, Dr. Engel will examine the mechanism by which two sites within the same molecule couple to form a cyclic molecule, and the mechanisms by which sites on one molecule react with another molecule to propagate the formation of the radical, and the subsequent growth of polymers with new molecular shapes and composition. Dr. Engel's educational activities involve training graduate and postdoctoral students in the synthesis of molecules containing azo and perester groups, their activation to form free radicals, and the characterization of the subsequent chemistry of these reactive intermediates.
