Progress in the synthesis of polyricinoleic acid via acid catalysis from the primary component of castor oil

There is a growing interest in utilizing components of oleaginous biomass to create polymeric materials. This study aimed to polymerize the triglyceride of ricinoleic acid, the primary constituent of castor oil, to produce polyricinoleic acid (PRA_triglyc) with varying weight average molar mass (Mw). Acid catalysis was selected due to its ease of use and cost-effectiveness. The first reaction generated a product (PRA1_triglyc) with Mw (from size exclusion chromatography) of approximately 6900 g/mol. The PRA1_triglyc nuclear magnetic resonance spectra, 1H and 13C confirmed the PRA_triglyc’s formation. Under different conditions of pressure and time, PRAs_triglyc 2–4 were synthesized, with Mw of approximately 12,000 g/mol, 17,000 g/mol, and 30,000 g/mol. This latter value is considerably higher than those reported in the literature in which non-enzymatic catalysts were used, as in this study. Thermogravimetric analysis showed that all synthesized polymers have thermal stability up to approximately 350 °C. PRAtriglyc’s are viscous liquids at room temperature and solids at − 20 °C. The solid-state undergoes a glass transition at approximately − 35 °C (from differential scanning calorimetry). Straightforward reactions yielded PRA_triglyc’s with a reasonable Mw range, making them ideal for use as polymeric chain extenders, macromonomers in copolymer synthesis, and other valuable contributions to the circular bioeconomy.