Synthesis and characterization of linear polyamides derived from L-arabinitol and xylitol

The synthesis and characterization of a new series of AABB-type polyamides based on L-arabinitol and xylitol are described. These linear polyamides were obtained by reaction of the aldaric acids or aliphatic dicarboxylic acids, with sugar-based diamine or aliphatic diamines. The pentaric diacids were activated as their pentachlorophenyl esters, and the diamino sugars were used as dihydrochlorides. Aliphatic diamines were used either as their activated trimethylsilyl derivatives or as the free bases. All the polyamides were soluble in the usual organic solvents, and those fully sugar-based were also soluble in water. All of them were very hygroscopic, especially those based on xylitol. DSC and X-ray powder diffraction studies showed that L-arabinitol-based polyamides were more crystalline than those derived from xylitol.