Novel fatty acid based di-isocyanates towards the synthesis of thermoplastic polyurethanes

Fatty acid derivatives have been successfully transformed into diisocyanates via a non-phosgene and green method. The structure of these novel diisocyanates was confirmed through FTIR and 1H NMR spectroscopies. These diisocyanates were reacted with commercially available and fatty acid based diols to obtain partially and fully bio-based polyurethanes respectively. The selected diols were of various structural features: with linear methylene spacers from 3 to 12 units, with sulfur-containing unit, ester linkages or cyclo-aliphatic units. The polyurethanes obtained were thoroughly characterized by FTIR, 1H NMR spectroscopy, SEC studies, DSC and TGA experiments. Most of the polyurethanes were semi-crystalline in nature with well-identified melting transitions. However, due to plasticization and/or conformational issues, insertion of methylene dangling chains or cyclic moieties imparted amorphous feature to the polyurethanes. The polyurethanes displayed fair thermal stability with no significant weight loss below 235 °C.