Sustainable aromatic polyesters with 1,5-disubstituted indole units

This work aims to unravel the impact of disubstitution patterns on the physical properties and processing characteristics of indole-based aromatic polyesters. A series of hydroxyl-carboxylate (AB-type) monomers with 1,5-disubstituted indole and 3-6 methylene units was conveniently synthesized and used in bulk polycondensation to yield the corresponding polyesters with decent molecular weight. These new monomers and polyesters showed enhanced thermal stability compared to the previously reported monomers and polyesters with a 1,3-disubstituted indole structure. According to DSC results, these polyesters showed tunable glass transition temperatures (T-g similar to 57-80 degrees C), depending on the length of the aliphatic methylene units. DSC and WAXD measurements revealed that these polymers did not crystalize from melt, but the ones with 3 or 5 methylene units per repeating unit crystalized from solution. Finally, we demonstrated that the new polyesters with 1,5-disubstituted indole units could be crosslinked using sustainable aromatic aldehyde, which could further enhance their thermal properties.

Automated summary

This study investigated the impact of disubstitution patterns on the physical properties and processing characteristics of indole-based aromatic polyesters. New monomers and polyesters with enhanced thermal stability were synthesized, showing tunable glass transition temperatures and improved solution crystallization. Additionally, the new polyesters could be crosslinked with sustainable aromatic aldehyde to further enhance their thermal properties.