Date of Award
Master of Science (MS)
Luis R. Cruz-Vera
Poly-beta-hydroxyalkanoates, Polymerization, Catalysis, Combinatorial chemistry
Polyhydroxyalkanoates (PHAs) are polyesters produced by many microorganisms and are used as an energy and carbon storage material within the cell. PHAs are biocompatible, biodegradable, and applicable to many fields. The spectrum of applications of PHAs can be broadened by post-polymerization chemical modification of the polymer side chain. Copper Catalyzed Azide-Alkyne Cycloaddition (“click” chemistry) can be used to bind different functional groups to these side chains. Different catalysts, solvents, and chelating nitrogenous ligands were evaluated to determine the conditions that yield 100% conversion of the side chain terminus to propargyl benzoate and propargyl acetate. Polymer analogous click conversions were performed using a synthetic PHA structural analog, poly (methylacrylate-co-5-bromo-1-pentene). Typical click conditions include CuSO4 and sodium-L-ascorbate in THF, which yields a 51.3% conversion to propargyl acetate and 60.1% conversion to propargyl benzoate. Using DMF as the solvent increases the degree of conversion by 15% for both click products. The presence of some nitrogenous ligands increases the degree of conversion by roughly 30%. Using the Cu(I) species CuBr(PPh3)3 in the presence of a nitrogenous ligand consistently yields 100.0% conversion for both click products.
Hession, Benjamin J., "Toward the chemical modification of polyhydroxyalkanoates using click chemistry : an investigation of desirable reaction conditions" (2020). Theses. 463.