Poly(1,12-dodecylene 5,5′-isopropylidene-bis(ethyl 2-furoate))-based sulfonated copolyesters: Effect of ionic groups and long chain aliphatic spacer on their thermo-mechanical properties, hydrodegradability and liquid water sorption

Poly (1,12-dodecylene 5,5′-isopropylidene-bis(ethyl 2-furoate)) has recently been introduced to the polymer field as an exceptionally flexible polyester derived from bio-based and cost-effective monomers. A partially sul- fonated version of this polymer is prepared in this study by copolymerization with sulfonated isophthalic acid. A series of sulfonated bisfuranic-aromatic copolyesters PDDbFXSIY, containing up to 50 mol% of sulfonated moi- eties was synthesized, for the first time, using the 1,12-dodecandiol as a comonomer. Their chemical structure was investigated by FTIR and NMR (1H and 13C) spectroscopy. In terms of properties, these copolyesters showed high thermal stability (c.a. Td,max ≥ 350 °C), a low glass transition temperature and they were found to be amor- phous up to 20 mol% of the sulfonated unit content. Hydrodegradability tests on PDDbFXSIY films carried out un- der alkaline conditions revealed highly stable materials even with increasing amount of sulfonated units. In addi- tion, the films exhibit good liquid water sorption, which increases as the amount of sulfonated groups decreases, following the opposite trend of previously reported sulfonated bisfuranic-aromatic copolyesters prepared using short-aliphatic chain diols. These properties are obviously related to the concurrently incorporation of a dodecy- lene chain and sulfonated groups in the same backbone, making it possible to generate new hydrolytically stable bisfuran-based polymers with a sorption feature.