Molecular Packing of Polyesters Derived from 1,4-Butanediol and Even Aliphatic Dicarboxylic Acids

Abstract

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.