Poly(butylene 2,5-thiophenedicarboxylate-co-glycolate) copolyesters with good degradation and barrier properties

In this work, poly(butylene 2,5-thiophenedicarboxylate-co-glycolate) (PBTFGA) copolyesters were synthesized from 2,5-thiophenedicarboxylic acid, 1,4-butanediol and glycolic acid. The influence of the glycolic acid content on thermal properties, mechanical properties and degradation capacity of copolyesters was systematically investigated. The glass transition temperature of copolyesters closely matched that of poly(butylene 2,5-thiophenedicarboxylate) (PBTF). While also demonstrating good thermal stability. When the glycolic acid content was low, the copolyesters exhibited some crystallization capability, but they gradually became fully amorphous as the glycolic acid content increased. The tensile tests revealed that the young's modulus of the PBTFGA copolyesters ranged from 69.2 MPa to 221.4 MPa. With elongation at break exceeding 659%, outperforming most biodegradable packaging materials. Copolyesters exhibited excellent gas barrier properties to both oxygen (PO₂ = 0.024 barrer) and carbon dioxide (PCO₂ = 0.029 barrer), both of which are superior to poly(butylene 2,5-thiophenedicarboxylate). The incorporation of glycolic acid significantly reduced the crystalline content of the copolyesters, facilitating the interaction of water molecules with ester bonds in the polymer backbone. The weight of poly(butylene 2,5-thiophenedicarboxylate-co-glycolate) was decreased significantly during enzymatic hydrolysis, indicating excellent degradation performance