2,4:3,5-Di-O-methylene-D-mannitol, abbreviated as Manx, is a D-mannitol-derived compound with the secondary hydroxyl groups acetalized with formaldehyde. The bicyclic structure of Manx consists of two fused 1,3-dioxane rings, with two primary hydroxyl groups standing free for reaction. A homopolyester made of Manx and dimethyl terephthalate as well as a set of copolyesters of poly(butylene terephthalate) (PBT) in which 1,4-butanediol was replaced by Manx up to 50% were synthesized and characterized. The polyesters had M w in the 30 000−52 000 g mol −1 range and a random microstructure and were thermally stable up to nearly 370°C. They displayed outstanding high T g with values from 55 to 137°C which steadily increased with the content in Manx. Copolyesters containing up to 40% of Manx were semicrystalline and adopted the crystal structure of PBT. Their stress− strain parameters were sensitively affected by the presence of carbohydrate-based units with elongation at break decreasing but tensile strength and elastic moduli steadily increasing with the degree of replacement.

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The crystal structures of a series of optically active polyamides derived from l-tartaric acid and 1,n-alkanediamines (n = 2, 4, 6, and 8) have been investigated. Experimental data provided by X-ray diffraction of powders and fibers as well as by electron diffraction of single crystals were used to determine the lattice parameters for each polymer. A triclinic unit cell with space group P1 was found to be shared by the whole series. Semiempirical quantum mechanical calculations revealed that the preferred conformation for these polytartaramides entailed the tartaric acid moiety in a gauche arrangement with the amide groups rotated out of the plane containing the all - trans polymethylene segment. Crystal models compatible with the crystallographic data were built and refined against X-ray diffraction intensities with the linked-atom least-squares (LALS) methodology. The favored structure appeared to consist of hydrogen-bonded pleated sheets packed with a stagger similar to that found in the α-form of nylon 66. Modeling performed with CERIUS, a program enabling on-line observation of the simulated X-ray and electron scattering as the molecular model is adjusted, led to substantially similar results.

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