Synthesis and properties of polyamides from 2,5-furandicarboxylic acid

The aim of this study is to investigate the synthesis of 2,5-furandicarboxylic acid (FDCA)-based copolyamides. Indeed, FDCA monomer may be a potential bio-based alternative to phthalic acids. A series of polyamides and copolyamides, PA 6-I(x)/6-F(y), are synthesized in a pilot scale reactor by melt polycondensation of salts based on FDCA, isophthalic acid (IPA), and 1,6-hexamethylenediamine. The chemical structure and composition of the resulting copolymers are extensively characterized by NMR (H-1, C-13, and 2D), MALDI-TOF as well as size exclusion chromatography and solution viscosimetry. Their thermal properties are studied by differential scanning calorimetry and TGA and also by a molecular modeling technique. It is pointed out that, during the synthesis, FDCA-rich polymers overcome a massive decarboxylation of FDCA, preventing the production of high molar mass polymers. It is also found that all polymers are amorphous and that the glass transition temperatures decrease as the amount of FDCA in the polymer increases. This is confirmed by the results from molecular dynamics. In addition, it is observed that the copolymers become more hygroscopic when the amount of FDCA in the copolyamides increases. However, the water uptake of PA 6-I(x)/6-F(y) with 90 > x > 50 is lower than those of PA6 and PA 66 polyamides. (C) 2017 Wiley Periodicals, Inc.