Towards Sustainable Polymerization: Biodiesel as a Green Polymerization Solvent

A number of polymer products have been traditionally made using a solution polymerization technique. However, with increased environmental awareness and thus, concerns over the volatile organic content (VOC) of various polymer processes, industry has been trying to find alternatives to traditional solvents.
In an effort to use cleaner technologies, biodiesel produced from canola oil was used as a polymerization solvent. Biodiesel or fatty acid methyl ester (FAME) is environmentally benign and has a low volatility. Because biodiesel is a high boiling solvent, its use can increase productivity by enabling polymerizations at elevated temperatures. This would result in faster reaction rates and thus, shorter reaction times.
Solution polymerizations of four commercially important monomers (i.e., methyl methacrylate (MMA), styrene, butyl acrylate (BA) and vinyl acetate (VAc)) were studied at 60°C and 120°C using biodiesel as a solvent. Reactions were carried out at different solvent concentrations to verify the effect of the biodiesel solvent on the polymerizations. Chain transfer to solvent rate constants were obtained using the Mayo method. These estimated chain transfer to solvent rate constants were employed in a polymerization simulator to predict the polymerization rates and cumulative average molecular weights of the polymer product. Moreover, to study the effect of feedstock a series of homopolymerizations was carried out at different solvent concentrations for two other biodiesel feedstocks: soybean oil and 50%yellow grease - 50%canola oil. Results were compared to FAME produced from canola oil.
The use of FAME or biodiesel as a renewable and cost-effective polymerization solvent with good solubility, low viscosity and high boiling point fulfills the requirements of a solution polymerization solvent in different cases. Therefore, the “environmental friendliness” of FAME, coupled with its effectiveness as a polymerization medium, makes it an attractive alternative to traditional polymerization solvents.