Acetylenic polyesters

Acetylenic polyesters containing either residues of 2‐butyne‐1,4‐diol, acetylenedicarboxylic acid, or both of them, were prepared and characterized. Polyesters of 2‐butyne‐1,4‐diol with succinic, adipic, and phthalic acids were obtained as soluble polymers by use of known methods. The polymaleate ester of 2‐butyne‐1,4‐diol was obtained either as a soluble or as an insoluble polymer, depending on the experimental conditions. Relatively high temperature or long reaction periods led to the formation of insoluble polymers. Polyesters of acetylenedicarboxylic acid with diethylene glycol, tetra‐ and hexamethylene glycols, 2‐butene‐1,4‐diol, and 1,4‐cyclohexane dimethanol were prepared by melt polycondensation in bulk. These polyesters were obtained as insoluble, rubbery materials, except those of 2‐butene‐1,4‐diol and 1,4‐cyclohexane dimethanol, which were obtained both as linear or as nonlinear polymers. The insolubility of the polyesters of acetylenedicarboxylic acid was due to crosslinking reactions involving the conjugated system CCCO. While the melt polycondensations in bulk involving either 2‐butyne‐1,4‐diol or acetylenedicarboxylic acid were entirely controlled reactions, those carried out between acetylenedicarboxylic acid and 2‐butyne‐1,4‐diol were very often associated with highly exothermic decompositions involving carbonization. The decompositions could be eliminated when the melt polycondensation in bulk was preceded by a fore‐condensation in solution. Solid, soluble, powdery low polymers (DP = 2–3) having softening temperatures of about 150–175°C. were thus obtained.