Vanillin-based resin for use in composite applications

Lignin is an abundant, renewable material that has the potential to yield valuable, low molecular weight, single aromatic chemicals when strategically depolymerized. In order to generate a highly bio-based thermoset for use in polymer composites, a lignin-derived chemical, vanillin, was methacrylated in a two-step, one-pot synthesis to produce a vinyl ester resin (87 cP at 25 °C) with a 1:1 mole ratio of a mono-functional monomer, methacrylated vanillin, to cross-linking agent, glycerol dimethacrylate. The synthetic scheme was solventless, required little catalyst and moderate reaction temperatures while generating no by-products. Upon resin curing, a hard, transparent thermoset with a broad glass transition, T_g = 155 °C (based on the tan δ maximum), and a temperature of maximum decomposition rate, T_max, of 426 °C was produced. Overall, a potentially 100% bio-based thermoset was synthesized possessing comparable thermo-gravimetric and thermo-mechanical properties to commercial vinyl ester-based thermosets.