Unlocking the potential of furan-based poly(ester amide)s

In this work, novel polyester amides (PEAs) based on renewable poly(propylene furanoate) (PPF) were prepared via traditional melt polycondensation utilizing a preformed symmetric amido diol (AD) containing two internal amide bonds. Owing to this innovative synthetic strategy, enhanced crystallization, both in terms of quantity and rate, was observed compared to neat PPF, which is characterized by slow crystallization kinetics. Moreover, the intramolecular hydrogen bonding usually observed in furan dicarboxylic acid (FDCA)-based polyamides, that results in the formation of low-molecular weight materials, was circumvented and copolymers of random structure and higher molecular weight were obtained. Due to the AD unit and the ensuing suppression of intramolecular hydrogen bonds, chain mobility (diffusion) is improved, leading in turn to enhanced crystallization. The crystallinity and crystal structure of PEAs were assessed via the combination of differential scanning calorimetry (DSC), X-ray diffraction (XRD) and polarized optical microscopy (POM). Furthermore, thermal degradation of the furan-based PEAs was thoroughly investigated for the first time, employing thermogravimetric analysis (TGA) kinetic modeling and Pyrolysis-Gas Chromatography-Mass Spectroscopy (Py-GC/MS). Finally, the complex molecular dynamics of PEAs was studied employing broadband dielectric spectroscopy (BDS). This study shows that PEAs have the potential to further enlarge the properties and applications of polyesters derived from FDCA.