Bio-based copolyesters incorporating hydrophilic functional groups and long hydrophobic chain: Synthesis toward chemical stability

In this work, we explore the insertion of up to 40 mol% of sodiosulfonate succinate moiety into the poly(1,12-dodecylene 5,5’-isopropylidene-bis(ethyl 2-furoate)) (PDDbF) polyester to create materials with a high bio-based content that combine the hydrophobicity of dodecylene chain and the hydrophilicity of sulfonated groups. PDDbF and four copolyesters, labelled as PDDbFXSSY, were synthesized using a modified two-step melt polycondensation reaction. FTIR and NMR (1H and 13C) analyses indicated the successful formation of the expected copolyesters. These materials displayed an amorphous structure with low glass transition temperature and enhanced thermal stability compared to their counterparts bearing 5-sodiosulfoisophthalate moiety, with maximum decomposition temperatures ≥ 410 °C.
Hydrolytic degradation tests, performed in aqueous media under acidic (pH = 4.5) and basic (pH = 11.5) conditions, showed high stability, attributed to the hydrophobic dodecylene chain. These features suggest strong potential for applications requiring combined hydrolytic stability, high flexibility and thermal robustness. Moreover, films prepared from PDDbF90SS10 showed significant mass gain after 4 weeks of immersion in distilled water, highlighting its water sorption capacity.