Synthesis and Characterization of Methacrylated Eugenol as a Sustainable Reactive Diluent for a Maleinated Acrylated Epoxidized Soybean Oil Resin

This work presents a solvent-free, facile synthesis of a renewable, aromatic monomer, methacrylated eugenol (ME), from eugenol and methacrylic anhydride by the Steglich esterification reaction. The resulting ME was subsequently used as a reactive diluent to copolymerize with a commercial maleinated acrylated epoxidized soybean oil (MAESO) resin to form renewable MAESO ME thermosets. The volatility of ME was examined, along with an analysis of viscosity and curing behavior of the MAESO ME mixtures. The curing kinetics, thermo-mechanical properties, and thermal stabilities of the fully cured MAESO ME thermosets with different ME proportions (0%, 20%, 40%, 60%, 80%, and 100%) were systematically investigated. The results indicated that ME monomer exhibited extremely low volatility (less than 3% mass loss after being held isothermally at 30 degrees C for 10 h), high biobased carbon content (BBC, 71.4%), and low viscosity (17.6 cP at 25 degrees C). Upon use with MAESO resin, viscosity of the system was considerably decreased. Compared with per equivalent of MAESO, ME-diluted systems exhibited higher reactivity, which resulted in improved curing extent and higher cross-link density of the MAESO-ME systems. The glass transition temperature (T-g) of MAESO-ME thermosets greatly improved from 61.1 to 139.3 degrees C with increasing ME loading from 0% to 100%. Overall, the developed biobased ME monomer is shown to be an effective, sustainable reactive diluent to replace styrene for commercially available MAESO resin.