Biobased high barrier copolyesters derived from furandicarboxylic acid and citric acid

Abstract

Biobased feedstocks developed from renewable resources play a crucial role in polymers. Dimethyl octahydro-2,5-pentalenediol (MeOPD) with excellent thermal stability and rigidity is a biobased bicyclic diol derived from citric acid. In this work, MeOPD was first reacted with dimethyl carbonate (DMC) to form oligo (dimethyl octahydro-2,5-pentalenediol carbonate) (OMC). Subsequently, a series of poly(butylene-co-dimethyl octahydro-2,5-pentalenediol furanoate-co-carbonate) (PBMFC) polyesters with MeOPD units ranging from 5 to 31 mol% were synthesized via melt polycondensation from OMC, dimethyl furan-2,5-dicarboxylate (DMFD) and 1,4-butanediol (BDO). Due to the low reactivity of MeOPD, its actual content in copolymer is much lower than that in the feed, and as the MeOPD content rises, the number-average molecular weight of PBMFCs drops from 25,200 g/mol of PBMFC5 to 12,800 g/mol of PBMFC31. Despite the presence of MC units weakens thermal stability, PBMFCs still maintain good thermal stability, evidenced by Td,5% ranging from 294-325 °C in N2 and from 295-339 °C in air. The mechanical properties are also satisfactory, exhibiting tensile modulus ≥ 500 MPa, tensile strength ≥ 23 MPa, and elongation at break ≥ 150 %. Compared to PET, PBMFCs demonstrate commendable gas barrier properties, with CO2 and O2 barrier capability being 4.7–11.0 times and 2.0–3.6 times that of PET, respectively. All results indicate that PBMFCs can serve as a renewable potential material for packaging application.