Free radical copolymerization kinetics of bio-based dibutyl itaconate and n-butyl acrylate
Tomaž Pirman, Connor A. Sanders, Martin Ocepek, Michael F. Cunningham, Blaž Likozar, Robin A. Hutchinson
Abstract
• 50% of bio-based itaconate has been incorporated into acrylic polymer resin. • Highly reactive acrylate facilitates the incorporation of itaconate. • The copolymer is synthesized under industrially-relevant operating conditions. • Radical copolymerization kinetics are studied in batch and semi-batch modes. • A comprehensive mechanistic model is developed to guide further development. The free radical copolymerization of dibutyl itaconate (DBI), a monomer derived from renewable resources, and n -butyl acrylate (BA) is investigated to explore the potential of incorporating itaconate monomers into commercial acrylic resins to enhance the sustainability of coating materials. Batch experiments were conducted at 50 °C and 80 °C, varying initial monomer and initiator concentrations as well as monomer compositions, with proton NMR and size exclusion chromatography used to analyze monomer conversion profiles and polymer molar mass distributions (MMDs). The data were analyzed using a kinetic model developed to guide the experimental studies and estimate key kinetic parameters controlling copolymer composition, polymerization rate and polymer MMDs. The use of the more reactive BA as comonomer significantly increases the conversion and molar mass of the resulting copolymer. Furthermore, semi-batch operating conditions similar to current industrial practice can incorporate a substantial fraction of DBI into acrylic copolymer resins, thus enhancing their sustainability profile.