Preparation
PGA synthesis typically employs a two-step ring-opening method: first, glycolic acid is converted to glycolide, and then glycolide undergoes ring-opening to produce PGA. Another reported method is melt/solid-phase polycondensation, where oligomers are first prepared in a molten state, then broken down and subjected to solid-phase polycondensation. This method has yielded high molecular weight PGA.
Polyglycolic acid (PGA) is initially derived from glycolic acid, which is widely found in nature, especially in sugarcane, sugar beets, and unripe grape juice. Due to the difficulty in its separation and purification, it is currently obtained industrially through organic synthesis.
Chemical Properties
Polyglycolic acid (PGA), also known as polyglycolide, was first reported in 1893, but it was not until 1967 that the first commercially successful patent was granted for sutures. Like polylactide, polyglycolide is synthesized from the cyclic diester. An important difference between polylactide and polyglycolide, is that polyglycolide (mp 220 C (428 F) is higher melting than poly-L-lactide (mp 170 C (338 F). Although the polymerization reaction in both cases is reversible at high temperature, melt processing of polyglycolide is more difficult because the melting temperature is close to its decomposition temperature. Unlike poly-L-lactide which is absorbed slowly, polyglycolide is absorbed within a few months post-implantation owing to greater hydrolytic susceptibility. In vitro experiments have shown the effect on degradation by enzymes, pH, annealing treatments, and gamma irradiation. Braided polyglycolide sutures undergo surprisingly rapid hydrolysis in vivo owing to cellular enzymes released during the acute inflammatory response following implantation.
Uses
Surgical aid (surgical suture material).
Definition
ChEBI: A polymer composed of repeating hydroxyacetic acid units.
