Synthesis and characterization of bio-based UV curable polyurethane coatings from algal biomass residue

Polyurethanes (PUs) are commonly used chemicals in various industries and are conventionally produced by the reaction of polyols and diisocyanates. However, synthetic petroleum-based polymers are non-biodegradable and resulting in issues like waste disposal, risks to aquatic and terrestrial ecosystems. In this study, a novel microalgal protein-based ultraviolet (UV) curing polyurethane acrylate (PUA) was prepared with hexanediol diacrylate (20% HDDA) precursor, amino acid oligomers, and photoinitiator (Irgacure 184). Experimental conditions for the synthesis of precursors were studied and their chemical structures were confirmed by FT-IR, (HNMR)-H-1, (CNMR)-C-13, and differential scanning calorimetry (DSC). The absorption peak at 1695 cm(-1) confirmed the formation of a urethane bond. For instance, the obtained polyurethane acrylate coating (PUA) possessed a glass transition temperature (T-g) of 122 celcius, tensile strength, modulus of 19.1 MPa, 465 MPa, and lower elongation break (6%). While using reactive diluents, the coating compositions showed significant enhancement of mechanical, physical, and chemical resistance properties. In general, this work offered a simple bio-scheme of reactions to prepare a sustainable microalgal-based PU coating that could be applied in the coating industry with improved properties.