Hindered Urea Bond Based Dynamic Chemistry and Polymer Synthesis

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With this award, the Macromolecular, Supramolecular and Nanochemistry Program of the Division of Chemistry is supporting Professor Jianjun Cheng of the University of Illinois at Urbana-Champaign to investigate the reversible bond-forming and bond-breaking processes of a novel type of polymers. Polymers containing reversible dynamic bonds may possess very useful properties such as self-healing, shape memory and environmental adaptation. For example, when there is a crack in the polymeric materials, polymers bearing dynamic bonds may allow self-repairing of the crack and restoration of material?s original mechanical strength. The knowledge gained from this research is disseminated through various endeavors including publications in scientific journals and presentations in summer camp programs and Engineering Open-House at the University of Illinois. This project provides research training opportunity to graduate and undergraduate students, including members of underrepresented groups, in the areas of organic synthesis and polymer chemistry.The reaction of an isocyanate and an amine is one of the most classical reactions in polymer chemistry that allows the preparation of polyurea, an inexpensive, widely used engineering polymer with very stable bulk property. While urea bond is a very robust covalent bond, it can be weakened by the presence of bulky substituent on one of the nitrogen atoms of the urea group because of bond distortion. Hindered urea bonds (HUBs) may undergo both fast association and dissociation reactions. Professor Cheng's group systematically studies the bond association and dissociation properties of various hindered urea structures, optimizes the dynamicity, and explores the properties and applications of HUB-bearing polymers. This work aims to yield polyureas and poly(urethane-urea)s capable of dynamic property change and autonomous repairing at low temperature without catalysts.