Novel Biobased Non-Isocyanate Polyurethanes from Microbially Produced 7,10-Dihydroxy-8(E)-Octadecenoic Acid for Potential Packaging and Coating Applications

In this study, a green and sustainable strategy was opted for the synthesis of a novel biobased non-isocyanate polyurethane (NIPU) or polyhydroxyurethane (PHU). NIPU or PHU was synthesized from microbially converted hydroxy fatty acid-based cyclic carbonate and diamine cross-linker. Initially, oleic acid was biotransformed into 7,10-dihydroxy-8(E)-octadecenoic acid (DOD) using Pseudomonas aeruginosa. The cell-free approach was chosen for DOD production due to its high yield and productivity. Afterward, DOD was modified into DOD-based tricyclic carbonate by a two-step method. The prepared monomeric material was characterized using Fourier transform infrared (FTIR) spectroscopy, ¹H nuclear magnetic resonance (¹H NMR), and ¹³C NMR analyses. A series of DOD-based PHUs (DOD PHUs) were synthesized with different amine contents, and their structures were studied by FTIR and ¹H NMR analyses. The morphological, mechanical, and thermal properties of DOD PHU were further analyzed. The tensile strength and elongation at break of the prepared DOD PHU were in the range of 2–6 MPa and 39–76%, respectively. The glass transition temperature of the material was in the range of 4–27 °C. Thermogravimetric analysis exhibited that thermal stability increases with the increase in amine content. The gel content was in the range of 73–100%, suggesting that the polymers are highly cross-linked. In addition, the synthesized DOD PHU displayed excellent ultraviolet and water resistance properties. The green synthesized DOD PHU depicts suitability for a wide range of applications, particularly in the coating and packaging industries.