Poly(ethylene 2,5-thiophenedicarboxylate-co-2,5-furandicarboxylate) copolyesters with improved ductility and PEF-comparable high performance

Poly(ethylene 2,5-furandicarboxylate) (PEF) is an important biobased polyester with not only high glass transition temperature (T-g), excellent strength and rigidity but also superior gas barrier properties. However, its poor ductility could limit its applications. In this study, 2,5-thiophenedicarboylic acid (TDCA) was used to modify PEF by copolycondensation. By introducing 10-40 mol% TDCA, poly(ethylene 2,5-thiophenedicarboxylate-co-2,5-furandicarboxylate) (PEThF) copolyesters with intrinsic viscosity of 0.63-0.77 dL/g were synthesized and characterized with H-1 NMR, DSC, TGA, etc. The copolyesters are all amorphous polymers. Brittle-ductile transition was observed during tensile testing of PETh10F (PEThF containing 10 mol% 2,5-thiophenedicarboxylate unit). PEThFs containing 20-30% 2,5-thiophenedicarboxylate unit showed not only clearly improved ductility but also well-maintained performance advantages of PEF including high T-g (84-81 degrees C), modulus (similar to 3.2 GPa), strength (yielding 95 MPa, breaking 60 MPa) and oxygen barrier (5.4-5.0 times PET).

Automated summary

In this study, PEF was modified by copolycondensation with TDCA, resulting in the synthesis of PEThF copolyesters. PEThF copolyesters exhibited high Tg, excellent strength and rigidity, as well as superior gas barrier properties. Moreover, the addition of 20-30% TDCA units significantly improved the ductility of PEF while maintaining its performance advantages.