High barrier semi-crystalline polyesters involving nature occurring pyridine structure towards sustainable food packaging

Abstract

This work contributes to develop bioplastics with high gas barrier properties. Here we reported a new bio-based semi-aromatic polyester poly(decylene 2,6-pyridinedicarboxylate) (PDePD26) for food packaging applications, synthesized from 2,6-pyridinedicarbonyl dichloride (PDD26) and 1,10-decanediol (DD) by a traditional polycondensation reaction. Two analogs, poly(decylene 2,5-pyridinedicarboxylate) (PDePD25) and poly(decylene isophthalate) (PDeIP) were also synthesized. The obtained polyesters were confirmed semicrystalline with M w ‾ higher than 50 000 g mol −1 . The structure polarity and geometric symmetry of the aromatic moieties revealed to be efficient tools to tailor the ability of crystallization, and then affect thermal, mechanical and transport performances. The polyesters containing pyridine rings (PDePD26 and PDePD25) showed lower thermal degradation temperatures (341 and 304 °C) than the one containing phenyl rings (PDeIP, 371 °C), but T g , T m and crystallinities were higher. PDePD26 displayed the preferred mechanical strength ( σ b = 12.5 ± 4.8 MPa) and elongation ( ε b = 25.0 ± 6.0%) at break. The highest gas barrier properties of PDePD26 were much better than PLA and comparable to amorphous PET. • A new bio-based polyester was synthesized from 2,6-pyridinedicarboxylic acid. • The high performance polyester was proposed for food packaging application. • The obtained polyester film had comparable gas barrier properties to amorphous PET. • The polar pyridine structure enhanced the polymer crystallization properties. • The asymmetric polar pyridine structure favored the gas barrier properties.