Poly(ether/ester)s based on poly(tetramethylene terephthalate) and poly(ethylene glycol), 4. Modification with 2-butyne-1,4-diol

A series of poly(ether/ester)s derived from dimethyl terephthalate, 1,4-butanediol, 2-butyne-1,4-diol (2-BD-1,4) and α-hydro-ω-hydroxypoly(oxyethylene) (molecular weight 1000) is synthesized. The mole ratio of the starting components is selected to result in copolymers with constant hard : soft segment weight ratio (59:41). The amount of 2-BD-1,4 is varied from 0 to 20 wt.-% referred to the total amount of the short-chain diols used. The incorporation of 2-BD-1,4 in the macrochains is proved by ¹H NMR measurements. A small increase of the oxygen index is found with increasing the amount of 2-BD-1,4. It is established that the poly(ether/ester) containing 10 wt.-% of 2-BD-1,4 behaves as known poly(ether/ester)s. Data from differential scanning calorimetry suggest a three-phase structure, two amorphous and one crystalline one. Small-angle X-ray studies of the annealed samples reveal a strong tendency to phase separation with increasing the annealing temperature. The latter is in agreement with density measurements.