Preparation and characterization of lactic/glycolic acid polymers and copolymers

A range of poly(L-lactic acid) [L-PLA], poly(DL-lactic acid) [DL-PLA], polyglycolic acid [PGA] polymers and PLA-PGA copolymers were synthesized from lactide and glycolide. The effect of lactide type, catalyst concentration, reaction time and reaction temperature was studied. Intrinsic viscosity determination, gel permeation chromatography, laser light scattering, nuclear magnetic resonance and differential scanning calorimetry were used to characterize the polymers formed. It was impossible to determine the molecular weight of most PGA samples due to lack of solubility. The consequences of the results with regard to the production and storage of microencapsulated and related products are discussed.