Isomorphic Polyoxyalkylene Copolyethers Obtained by Copolymerization of Aliphatic Diols

Isomorphism in random copolymers occurs when comonomer units can crystallize within a single crystalline lattice in the entire composition range. This ideal behavior is rare in random copolymers, and only a few examples of isomorphism are found in copolyesters and copolycarbonates. In this work, we show a series of polyoxyalkylene copolyethers obtained by copolymerization of 1,6-hexanediol and 1,12-dodecanediol which can crystallize in the entire composition range and display an isomorphic behavior. The copolymers were synthesized via a bulk self-condensation method at high temperature, using a thermally stable noneutectic mixture organocatalyst (NEMO) prepared from methanesulfonic acid (MSA) and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD). The final molar ratios of the copolyethers were calculated by 1H NMR spectroscopy, and the random distribution of the two monomeric units was confirmed by 13C NMR spectroscopy. The effect of the composition of comonomer units on the crystalline structure was investigated...