Sustainable polyurethane coatings based on functional Camelina oil-based polyols

Abstract

Polyurethane (PU) coatings have garnered considerable attention across diverse applications and industries, owing to their versatile physiochemical attributes. Despite their widespread use, the environmental implications associated with their carbon footprint have raised concerns in recent years. To address this issue, we explored the potential of Camelina oil as a base chemical for synthesizing polyesteramide polyols as a viable alternative to petrochemical-based materials. Consequently, we formulated biocarbon-rich polyurethane coatings using the synthesized polyols. Initially, we synthesized a fatty amide intermediate through a transamidation reaction, involving the interaction of diethanolamine and triglyceride. Subsequently, we produced three distinct polyesteramide polyols using citric acid, itaconic acid, and phthalic acid. To confirm the formation of ester and amide linkages, we employed various structural analyses, including Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared (FTIR) spectroscopy, on the Camelina-oil-derived polyols. Furthermore, we utilized quantitative techniques such as titration to ascertain hydroxyl number, acid number, and amine value. Our structural analyses corroborated the establishment of ester linkage and the incorporation of OH functionality in Camelina oil, while titration results indicated a remarkable 1200 % surge in hydroxyl value. We subsequently employed the three polyesteramide polyols to fabricate polyurethane coatings, subjecting them to a battery of tests. The resultant biobased coatings were assessed using Dynamic Mechanical Analysis (DMA), Thermo-Gravimetric Analysis (TGA), and an array of surface characteristics such as gloss, hardness, impact resistance, water contact angle, and saline resistance. All tested samples exhibited satisfactory thermal stability, with the biocarbon content of the final PU coatings measuring at least 61.6 %. Moreover, our study demonstrates that the derived polyurethane coatings hold promise for non-wet applications, particularly in the realm of interior coatings.