Precision Polyolefins Embracing Tacticity, Amorphous Structure Control, and Precision-Enhanced Biological Activity

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TECHNICAL SUMMARY:Tactic versions of precision polyolefin materials are being prepared to define the importance of proximity of precisely placed chiral centers in a linear polymer chain. The chain-length distance between these chiral centers is of special interest. Crystallization will be examined in detail via variable temperature X-ray techniques and thermal analysis. The precision work will be extended to a systematic study of commercially prepared metallocene-generated polyethylene, since it is now possible to space branches as far apart as 75 carbons. Long-chain alkyl branches will be precisely attached far apart from each other, and the morphological structure of these materials will be explored.The morphology of highly interactive structures, including those possessing ionic liquid entities, will be elucidated as well. Preliminary research suggests that ionic liquid entities, when placed precisely in the polymer backbone, lead to enormous inter-chain interaction in these materials. A detailed study of performance (tensile strength, shear thickening, etc.) as a function of counterion identity comprises a major part of this work. The research will be done in collaboration with expert morphology research groups in the USA, Germany, and Japan.Finally, the PI will synthesize water-soluble versions of these precision materials. Potential uses for water-soluble polymers are quite large. Of particular interest will be a study of ion binding in these water-soluble macromolecules. The research will begin using precision linear copolymers possessing both in-chain and grafted poly(oxyethylene) in varying amounts. The biological activity of these materials, particularly in terms of chiral response, will be measured as well.NON-TECHNICAL SUMMARY:Better understanding of the behavior of the world's largest-volume plastic, polyethylene, comprises a major theme in this research. The PI and his group will prepare polyethylene analogues whose molecules contain branches at regular intervals, thus creating materials with precisely defined architectures. The properties of these materials will be studied with a variety of techniques. The research itself serves as an educational tool at both the undergraduate and graduate level, where the impact of interacting young scientists from a variety of countries is important. For example, a "Research Abroad for Graduate Students" program has been established to give students global exposure. Included are interactions created by government institutions (such as found in Germany at the Max Planck Institute for Polymer Research). Further, the PI will continue to seek and educate undergraduate students who are in the "Florida Opportunity Scholars Program" and who are the first in their families to go to college.