Aliphatic Polyesters of Butyne‐1,4‐Diol

Polyesters of butyne‐1,4‐diol (ByD) and aliphatic dicarboxylic acids (ADAs) were prepared in three different ways. Method I is based on the transesterification of ByD with the dimethyl esters of ADAs in bulk. Although catalyst and temperature were varied, only oligomers were obtained, because even at 220 °C the conversions were far from complete. Higher molar masses resulted from method II, the acid‐catalyzed polycondensation of ByD with sebacic acid, but this method yielded a high fraction of ether groups. The best results were obtained from method III, which consisted of pyridine‐catalyzed polycondensations of ByD and various ADA dichlorides at 0–20 °C. SEC measurements yielded corrected number average molecular weights ( M ₙ ) up to 20 000 Da. The success of this method depended largely on the excess of the ADA dichloride in the feed ratio. MALDI‐TOF mass spectrometry evidenced that under optimized reaction conditions the chain‐growth was mainly limited by cyclization. With the exception of the polysuccinate, all polyesters were rapidly crystallized materials with melting temperatures in the range of 50–90 °C. magnified image