Chemical Recyclable Bio-Based Semiaromatic Polyamides: Synthesis and Properties

Furan-based semiaromatic polyamide is a promising alternative to petroleum-based counterparts. However, weak and few intermolecular hydrogen bonds result in limited thermal stability and amorphous properties, which could not meet the requirements of various applications. Herein, a series of furan-based semiaromatic polyamides (FPAs) were synthesized from dimethyl furan-2,5-dicarboxylate and long-chain aliphatic diamines containing oxalamide with double hydrogen bonds (LADOs). A two-step melting polycondensation in one pot was systematically investigated. Wide-angle X-ray diffraction and differential scanning calorimetry indicate that the resultant polyamides were semicrystalline. Temperature-variable FTIR experiments suggested the presence of hydrogen bonds in the polymer chains. With the decrease in carbon chain length of LADOS (except 1,5-diaminopentane-based monomer), T_m (179-257 °C) and T_g (57-103 °C) gradually increased. Thermogravimetric analysis showed T_d,5% and T_d,max in a range of 338 to 412 °C and 446 to 473 °C, respectively. Besides, polymers exhibited excellent fluorescence characteristics and chemical resistance. Finally, FPAs could be depolymerized into initial monomers, indicating a circular polymer economy. Overall, these FPAs present a potential as bio-based materials alternative to polymers derived from fossil fuels, and this work provides a strategy for high-performance materials.