Synthesis and performance study of High-Barrier Bio-Based biodegradable polyesters derived from Thiophene-2,5-Dicarboxylic acid

The bio-based high gas barrier polyesters play an important role in the food packaging field. In this study, a new bio-based polyester poly(pentamethylene 2,5-thiophene dicarboxylate) (PPeTh) was synthesized by melting polycondensation from thiophene-2,5-dicarboxylic acid and pentanediol and systematically compared with the properties of counterpart polyesters derived from both petroleum-based poly(pentamethylene terephthalate) (PPeT), poly(pentamethylene isophthalates) (PPeI) and bio-based poly(pentamethylene 2,5-furoate) (PPeF). The results indicated that PPeTh, PPeF, PPeT, and PPeI all exhibited excellent thermal stability. PPeTh showed a higher tensile strength and elongation at break compared to PPeT (σ b : 22.5 MPa, ε b : 975 %), and it also surpasses PPeF in terms of elastic modulus, yield strength, and elongation at break (E: 455 MPa, σ y : 17.6 MPa, ε b : 975 %). Furthermore, PPeTh exhibited superior gas barrier properties (BIFp(CO 2 ):67.05, BIFp(O 2 ): 16.89) and demonstrates potential biodegradability in the presence of CALB enzyme and composting conditions. A series of results suggested that the bio-based polyester PPeTh possesses the best overall performance, outperforming PPeF and exceeding that of petroleum-based polyesters PPeT and PPeI, indicating its potential application value.