Syntheses of Polyglycolide via Polycondensation: A Reinvestigation

Abstract

AbstractThe Na salt of chloroacetic acid is condensed in suspension. Furthermore, glycolic acid is condensed in bulk or in concentrated solution by means of SnCl2 or 4‐toluene sulfonic acid (TSA) as catalysts. The temperatures are varied from 160 to 200 °C and the time from 1 to 5 days. Low molar mass cyclic poly(glycolic acid) (PGA) is detected by means of matrix‐assisted laser desorption ionization time‐of‐flight (MALDI TOF) mass spectrometry in most PGAs. A predominance of certain cycles having an even number of repeat units is observed suggesting a thermodynamically favored formation of extended‐ring crystals. Extremely high melting temperatures (up to 237.5 °C) and high melting enthalpies are found for polycondensations with TSA in 1,2‐dichlorobenzene.