Macrocycles 27: Cyclic aliphatic polyesters of isosorbide



Numerous polycondensations of isosorbide and suberoyl chloride or other aliphatic dicarboxylic acid dichlorides were performed with pyridine as a catalyst and HCl acceptor. The reaction conditions were varied to optimize both the molecular weight and the fraction of cyclic oligo- and polyesters. Furthermore, we attempted to obtain the cyclic monomer by catalyzed back-biting degradation of the molten cyclic polyesters above 220 °C in vacuo. The polyesters were characterized by viscosity and size exclusion chromatographic measurements as well as matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. In selected cases, mixtures of linear and cyclic polyesters were treated with a hot solution of partially methylated β-cyclodextrin in methanol. This treatment allowed for a selective extraction of the linear chains up to approximately 5000 Da. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3414–3424, 2003