Copolyesters of Lactide, Isosorbide, and Terephthalic Acid‐Biobased, Biodegradable, High‐ T g Engineering Plastics

Various copolyesters of lactide, isosorbide, and terephthalic acid are prepared by a two‐step process performed in a “one‐pot” procedure, beginning with an isosorbide‐initiated oligomerization of L ‐lactide followed by polycondensation with terephthaloyl chloride using SnCl 2 as a catalyst for both steps. The SEC data show the formation of random copolyesters with high polydispersities as a consequence of the relatively high fraction of cyclics proved by matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry (MALDI‐TOF MS). The glass‐transition temperatures (89–180 °C) obey an almost linear trend with the molar composition. The thermostability decreases with increasing lactide content. The successful incorporation of phenyl phosphate results in copolyesters of lower inflammability.