Discipline: Chemistry and Chemical Sciences
Subcategory: Chemistry (not Biochemistry)
Jasmine Shamera Phillips - Savannah State University
Co-Author(s): Pascal Binda, Savannah State University, Savannah, GA
Since the post-World War II era, there has been an increase in the use of synthetic, petroleum-based polymers such as polyethylene, polyvinylchloride, and polystyrene. Although these polymers have had a large industrial impact, substantial drawbacks have occurred. Conventional plastics are made from non-renewable petroleum resources, which will eventually contribute to depletion of fossil-fuel. Experts in the chemistry and chemical engineering fields have been working to replace these conventional polymeric materials with sustainable, environmentally friendly biodegradable polyesters produced from natural resources such as corn/sugar beets. Polyesters are produced from cyclic esters using homogenous metal-based catalytic system of the form LLnX, where L represents a chiral dianionic multidentate ancillary ligand, Ln represents a highly electropositive trivalent lanthanide metal, and X is an initiator, such as isopropoxide and trimethylsilylamide. Lanthanides are preferred because they are highly electropositive, inexpensive, hard and oxophilic metals that are proven to have good reactivity towards unsaturated gamma lactones. Furthermore, the reduction in metal size (lanthanide contraction) from La and Nd allows variety in the catalytic pocket for controlled polymerization with less side reactions. Six new heteroleptic lanthanide complexes supported by new chiral [ONO] ancillary phenolate ligands with varying pendants have been synthesized via ligand exchange and salt elimination reactions: [LB2LaN (SiMe3)2] (1), [LB2NdN(SiMe3)2] (2), [LB2LaOiPr] (3), [LB2NdOiPr] (4), [(L72)LaN(SiMe3)2] (5), and [(L72)LaOiPr] (6). These new compounds will be fully characterized via nuclear magnetic resonance (NMR) and elemental analysis. The heteroleptic lanthanide complexes will then be investigated as chiral catalysts for the ring-opening polymerization of gamma lactones to obtain cross-linkable polyesters containing unsaturated alkenes as pendent arm.
Funder Acknowledgement(s): I thank Dr. Binda for mentoring me in the lab. I also thank Dr. Chetty, Dr. Mustafa, and Ms. Chellu for their help. The research conducted was funded by the National Science Foundation. I thank NSF-PSLSAMP for all the support I have received.
Faculty Advisor: Pascal Binda,