Linseed oil polyol/ZnO bionanocomposite towards mechanically robust, thermally stable, hydrophobic coatings: a novel synergistic approach utilising a sustainable resource

Abstract

Linseed oil polyol/ZnO bionanocomposite was prepared to obtain mechanically robust, thermally stable, hydrophobic coatings via a novel synergistic approach utilising a vegetable oil polyol for the first time. The synthesis process obviates the use of reducing agents, surfactants, reaction media, stabilizing agents, solvents, and other chemicals. Linseed polyol serves the purpose of obtaining ZnO nanoparticles. The linseed polyol backbone hosts hydroxyl and carboxylic groups that participate in the generation of ZnO nanoparticles in the polyol matrix (ester elimination, addition–elimination reaction). The progress of the reaction was monitored by recording FTIR spectra at regular intervals of time. The coatings obtained were scratch-resistant, impact-resistant, well-adherent, flexibility-retentive and hydrophobic, showing good chemical resistance under acidic, alkaline, and salt environments. Thermogravimetric analysis revealed that these coatings could be safely used up to 250 °C. The work described is consistent with the principles of “Green Chemistry” (Principles 1, 2, 3, 4, 5, 6, 7, 8, and 12), such as utilising a renewable feedstock, resorting to a solventless approach, and employing safer chemistry. The results showed that these coatings may be well employed as promising candidates towards environmentally friendly corrosion protective coatings.