Syntheses, Characterizations, and Structures of a New Series of Aliphatic−Aromatic Polyesters. 1. The Poly(tetramethylene terephthalate dicarboxylates)

A new family of polyesters, the poly(tetramethylene terephthalate dicarboxylates) of formula [−O−CO−C6H4−CO−O−(CH2)x−O−CO−(CH2)y−CO−O−(CH2)x]n, was synthesized and characterized by 1H and 13C NMR in CDCl3 solution, infrared spectroscopy, molecular weight distribution, and X-ray fiber diffraction analysis. The 1H and 13C NMR spectroscopy and the molecular weight distribution confirm the homogeneous alternating distribution of the two kinds of diacids (aromatic and aliphatic). The crystal structures of the adipate and the succinate were determined by interpretation of their X-ray diffraction patterns. A dynamic infrared spectroscopic study confirmed the existence of a nongauche−nontrans torsion angle in the glycol segments, while the diacid moieties were in a nearly all-trans conformation.