Glycolide and lactide function as the commonly used diester monomers for the preparation of high-molecular weight, degradation-prone (co-)polyesters. Both glycolide and lactide-based polymers are widely used in medicine, pharmaceuticals, the food industry, and additive technologies. This review on the diesters, spanning research from 1833-1854 to the present, encompassing their structural peculiarities, physico-chemical properties, and the range of different methods for obtaining themincluding reaction mechanismsfrom lactic and glycolic acids, their esters, and halogen derivatives. The review also discusses the chemical transformations of lactide and glycolide (apart from ring-opening polymerization) into valuable organic and high-molecular compounds, such as acrylic acid, nitrogen-containing heterocycles, and functional polymers with novel properties.

No abstract

For glycolic acid oligomers (GAO): l-lactic acid oligomers (LAO) mixtures, as an example, it was shown that the nature of the active sites of the catalysts significantly affect the depolymerization process. So, ZnO, which has mainly basic sites, leads to the highest yield of cyclic diesters. On the contrary, depolymerization in the presence of acidic γ-Al2O3 and without a catalyst is characterized by lower diester yields due to the prevalence of a side polycondensation reaction. Using GAO:LAO mixtures, it was shown that in the case of three studied systems (with ZnO, γ-Al2O3, and without catalyst), mixed interactions occurred, including homo-paired and hetero-paired intermolecular interactions, as well as intramolecular interactions of oligomeric molecules. Kinetic models of the processes under study were determined by isoconversional thermal analysis. In the case of depolymerization of oligomers in the presence of ZnO, the kinetic model was between the kinetic models of the first (F1) and second (F2) orders, while in depolymerization in the presence of γ-Al2O3 and without a catalyst, the process was described by diffusion models such as the Jander equation (D3) and Zhuravlev, Lesokin, Tempelman equation (D5).

No abstract

This work is dedicated both to investigation of the influence of different conditions on the molecular weight characteristics of poly- ε-caprolactone (PCL) and to the synthesis of composites based on PCL and hydroxyapatite (HA) by in situ and mechanical mixing methods. It was shown that in situ synthesis is accompanied by chemical interactions between PCL and HA that were confirmed by IR spectroscopy and thermal analysis. The morphology of in situ obtained composites has more homogeneous and regular distribution of HA particles in the polymeric matrix than composites synthesized by mechanical mixing of HA and PCL.