Synthesis of Poly(Lactoylglycolate): An Alternating Copolymer of Lactic and Glycolic Acids

Abstract

Abstract : Copolymers of lactic and glycolic acids have been traditionally synthesized by the copolymerization of lactide and glycolide, which are cyclic dimers of lactic and glycolic acids, respectively. When these two monomers are copolymerized by ring-opening polymerization, the result is a random diad of glycolic and lactic acids. Furthermore, due to the different reactivities of the two comonomers, glycolide- and lactide-rich regions would result in addition to the random regions. These problems cause the polymer to have variability in their properties from batch-to-batch. Also, by making the polymer more random, the polymer will not be able to crystallize. To synthesize an alternating copolymer of lactic and glycolic acids requires a monomer that is a hybrid of lactide and glycolide. This monomer is called 3-methylglycolide or 3-methyl-1, 4-dioxan-2, 5-dione according to IUPAC nomenclature. Three approaches were attempted out of four proposed routes. The most viable route involved the reaction of sodium glycolate with 2-bromopropionyl bromide. Keywords: Polylactic acid; Polyglycolic acid; Copolymer; Polymer; Synthesis(chemistry); Glycolic acid.