Synthesis and characterization of bio-based polyesters from 2,5-thiophenedicarboxylic acid

Abstract Six kinds of 2,5-thiophenedicarboxylic acid-based polyesters were synthesized using a two-step melt polycondensation method from 2,5-thiophenedicarboxylic acid (TFDCA) and aliphatic diols. For all polyesters synthesized, weight-average molecular weight was higher than 1.8 × 104 g mol−1. For poly(hexylene 2,5-thiophenedicarboxylate) (PHTF), poly(octylene 2,5-thiophenedicarboxylate) (POTF), and poly(decylene 2,5-thiophenedicarboxylate) (PDTF), they were crystalline polymers due to long crystallizable polyethylene-like hydrocarbon segments in the backbone. However, for poly(2-methyl-1,3-trimethylene 2,5-thiophenedicarboxylate) (PMTF), poly(neopentyl glycol 2,5-thiophenedicarboxylate) (PNTF), and poly(pentylene 2,5-thiophenedicarboxylate) (PPeTF), the melting temperature was not observed. PMTF was a brittle material (elongation at break∼2%). However, other TFDCA-based polyesters were ductile materials (elongation at break>110%). For PNTF, the highest tensile strength (∼63 MPa) and moderate elongation at break (113%) were observed, which were comparable with that of polyethylene terephthalate (PET). The polyesters prepared could be very significant for the development of bio-based polyesters.