The crystalline structures of polyesters 4 8, 4 10, and 4 12 have been studied using X-ray and electron diffraction and real space electron microscopy. They belong to the series of polyesters derived from 1,4-butanediol and even-dicarboxylic acids. This work allows the previously reported data on polyesters 4 4 and 4 6 to be extended. The new polymers adopt an all-trans conformation and pack according to orthorhombic unit cells that contain four molecular segments. This feature contrasts with the smaller unit cells reported for other poly(alkylene dicarboxylate)s which have also an all-trans conformation. Molecular simulation has been used to calculate the diffraction patterns and determine the main packing features. Lamellar crystals with a truncated lozenge morphology are obtained by isothermal crystallization of dilute alcohol solutions. A regular folding habit on the different lamellar sectors is evident by using polyethylene decoration techniques. Thin films of negative birefringent spherulites are obtained by melt crystallization and their electron diffraction patterns studied.

The crystalline structure of polyester 6 6 was studied by means of X-ray and electron diffraction and real-space electron microscopy. An orthorhombic unit cell containing eight chain segments with a quasi planar zigzag conformation was derived. The chain axis projection could be defined by a small rectangular cell containing only two molecular segments. Simulation of electron diffraction patterns indicates that molecular segments were arranged with azimuthal angles close to +/-46 degrees . X-ray diffraction patterns suggested that the large dimensions of the unit cell were a consequence of a slight shift between neighboring chains that improved the electrostatic interactions. Chain-folded lamellar crystals were obtained by isothermal crystallization of dilute n-hexanol or n-octanol solutions. The crystalline habit was studied, and the influence of temperature was evaluated. A regular folding surface was observed by using polyethylene decoration techniques. Lamellar crystals were easily degraded with different lipases. A preferential enzymatic attack was, in some cases, observed to occur in the crystal edges, giving rise to highly irregular borders with a fringed texture.

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