Unsaturated copolyesters of lactide

Four classes of unsaturated copolyesters of L-lactide were prepared either from isosorbide or bis(hydroxymethyl) tricyclodecane in combination with fumaric acid or from 1,4-butenediol or 1,4-butynediol with terephthalic acid. All syntheses were performed in such a way that lactide was oligomerized with a diol as the initiator and the resulting oligomers were polycondensed with a dicarboxylic acid dichloride either in a one-pot synthesis or in a two-step procedure. For most copolyesters the SEC measurements gave weight average molecular weights in the range of 30-60 kg mol(-1) and dispersities in the range of 4.2-6.2. The MALDI-TOF mass spectra displayed a high content of cycles and indicated an irreversible kinetic course of all polycondensations. Glass-transition temperatures (T-g) above 90 degrees C were only found for two copolyesters of isosorbide. Addition of bromine to copolyesters of 1,4-butenediol yielded flame retarding biodegradable polymers.