Collaborative Research: Exploring the role of branching in determining the physicochemical properties of dendritic, hyperbranched and linear bis-MPA polyesters

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A significant percentage of the materials around us are made from plastics, also referred to as "polymers". The vast majority of synthetic polymers exhibit a linear structure, resembling a string, on the molecular level. Within the last few decades, a number of branched polymers, with a more tree-like molecular structure, have been designed and made commercially. The difference in structure from linear to branched results in unique properties and applications. Professor Grayson at Tulane University and Professor Nazarenko at the University of Southern Mississippi are using new synthetic methods to control the exact amount of branching in a family of polyesters. They study the properties of the polyesters to better understand how controlling polymer structure on the molecular level can yield polyesters with improved behavior and performance. This effort engages researchers from both the undergraduate and the graduate levels in a multi-disciplinary, collaborative approach. This project also include outreach to local public high school chemistry classes to demonstrate the use of the scientific method to better understand fundamental concepts in chemistry. A new interdisciplinary archeological chemistry course is also under development. With the support from the Macromolecular, Supramolecular and Nanochemistry Program from the Division of Chemistry, new synthetic tools are being employed to prepare a library of linear, hyperbranched, dendritic and "pseudodendritic" polymers based on the bis(hydromethyl)propanoic acid monomer. Both traditional (nuclear magnetic resonance) and more novel (mass spectrometry) characterization techniques are being utilized to elucidate the structure as well as the reactivity of each architectural class of these polymers. X-ray studies are combined with computer modeling to confirm the nature of the intra-and inter-molecular hydrogen bonding that occurs in these polyesters. Pressure-volume-temperature studies are carried out to understand the molecular packing in the melt and solid states. Finally, the materials dielectric properties are being investigated and correlated with the type of branching, as these materials show promise for high dielectric constant materials.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.