Towards Sugar-Derived Polyamides as Environmentally Friendly Materials

As part of our ongoing study investigating isohexide-based polyamides we have synthesized<br/>isosorbide(bis(propan-1-amine)) (DAPIS) and studied its reactivity in the polymerization towards fully<br/>biobased polyamides. Polycondensation of nylon salts with various contributions of DAPIS afforded a<br/>10 family of homo- and copolyamides, which were characterized using complementary spectroscopic<br/>techniques. The chemical structure of the materials was determined by FT-IR, 1D and 2D liquid-state<br/>NMR spectroscopy, whilst the supramolecular arrangement, conformational changes upon heating, and<br/>molecular mobility of the polymers were investigated by solid-state 13C{1H} Cross-Polarization/Magic-<br/>Angle Spinning (CP/MAS) NMR and 13C{1H} Insensitive Nuclei Enhanced by Polarization Transfer<br/>15 (INEPT) experiments. The abundance of the different DAPIS conformers was determined by DFT-D<br/>computational methods. The thermal properties of the polyamides were tested for polymers with different<br/>amounts of isohexide units in the backbone by DSC and TGA, demonstrating that increasing amounts of<br/>isohexide diamine efficiently decreases their melting point and slightly their thermal stability. The<br/>relaxation processes of the isohexide-derived polyamides were studied by DMTA