Brown Grease as a Precursor to Polyol Monomer for Polyurethane Synthesis

Abstract The valorization of waste‐derived feedstocks for polymer synthesis represents a sustainable alternative to petroleum‐based materials. In this study, brown grease, a low‐value waste lipid source, is utilized as a precursor for polyol monomer synthesis via a two‐step functionalization process. Transesterification of brown grease with allyl alcohol generates allyl esters, which are subsequently modified via thiol‐ene click chemistry with 2‐mercaptoethanol to yield hydroxyl‐functionalized polyols ( BG‐diol ). The thiol‐ene reaction proceeds under mild UV‐initiated conditions, achieving high conversion efficiency (>90%) while preserving the structural integrity of the derived polyol. BG‐diol is further polymerized with 4,4′‐methylene diphenyl diisocyanate (MDI) through step‐growth polymerization to form brown grease‐derived polyurethane ( BG‐PU ). Comparative analysis of BG‐PU with polyurethane (PU) synthesized from purified oleic acid ( OLA‐PU ) demonstrates comparable molecular weight distributions ( M n = 14.4 kDa, M w = 20.4 kDa for BG‐PU ) and thermal properties ( T g = 24 °C, T d,5% = 270 °C for BG‐PU ). These results underscore the feasibility of brown grease as a cost‐effective and renewable alternative to plant oil‐based polyols, offering a pathway toward sustainable PU production while mitigating food security concerns. This approach exemplifies the potential of waste lipids in circular economy strategies for high‐performance polymer synthesis.