Synthesis and Properties Investigation of Thiophene-aromatic Polyesters: Potential Alternatives for the 2,5-Furandicarboxylic Acid-based Ones

In order to explore new substitutes for 2,5 furandicarboxylic acid(FDCA)or poly(ethylene 2,5 furandicarboxylate)(PEF)and try to develop more ideal bio based polyesters,several thiophene aromatic polyesters(PETH,PPTH,PBTH,and PHTH)were synthesized from dimethyl thiophene 2,5-dicarboxylate(DMTD)and different diols,including ethylene glycol,1,3-propanediol,1,4-butanediol,and 1,6-hexanediol.The chemical structures of obtained polyesters were confirmed by nuclear magnetic resonance spectroscopy(H-NMR and 1'C-NMR).Determined by GPC measurement,their average molecular weight(M.)varied from 5.22 x 10*g/mol to 7.94 x 10*g/mol with the molar-mass dispersity of 1.50-2.00.Based on the DSC and TGA results,the synthesized polyesters PETH,PPTH,and PBTH displayed comparable or even better thermal properties when compared with their FDCA-based analogues.From PETH to PHTH,their Tg varied from 64.6°Cto-1°C while Tsm ranged from 409 C to 380°C in nitrogen atmosphere,PETH showed elongation at break as high as 378%,tensile strength of 67 MPa,and tensile modulus of 1800 MPa.Meanwhile,the CO2 and O2 barrier of PETH was 12.0 and 6.6 folds higher than those of PET,respectively,and similar to those of PEF.Considering the overall properties,the synthesized thiophene aromatic polyesters,especially PETH,showed great potential to be used as an excellent bio based packaging material in the future.