Single crystal morphology and structural data of a series of polyesters derived from 1,8-octanediol

Abstract

The morphology of solution grown single crystals of a series of polyesters derived from 1,8-octanediol and either an even or an odd dicarboxylic acid has been investigated. Different crystallization conditions (solvent and temperature) were tested for these polyesters whose dicarboxylate unit varied from pimelate to sebacate. Crystals showed a lozenge morphology with a degree of truncation which for a given solvent changed with the crystallization temperature. Curvature of growth faces, striations on the lamellar surface and a bilayered morphology were features that were observed in some cases. Polyethylene decoration highlighted a crystal sectorization and suggested a molecular folding parallel to the crystal growth faces. The studied polyesters always showed a single crystalline structure, according to electron and X-ray diffraction data. A practically all trans molecular conformation could always be deduced. Unit cell geometry changed from orthorhombic to monoclinic and the molecular content was variable in the studied series (two or four molecular segments). Lamellae gave rise to well-defined electron diffraction patterns that allowed the setting angle of molecular segments to be determined. A good agreement between simulated and experimental hk0 diffraction patterns was always found. Packing along the chain axis direction was completely defined for the sebacate derivative.