Fully bio-based aliphatic thermoset polyesters via self-catalyzed self-condensation of multifunctional epoxy monomers directly extracted from natural sources

The use of bio-based raw material is regarded as a sustainable way to address environmental concerns. A naturally occurring monomer, 9,10-epoxy-18-hydroxyoctadecanoic acid (EFA), was retrieved from outer birch bark. A series of model experiments revealing relative reaction rates for epoxide, carboxylic acid, and alcohol functional groups was investigated. Real-time Fourier transform infrared spectroscopy and nuclear magnetic resonance were used to follow the different model experiments. The results on the model systems were then compared to the thermoset formation of thermally cured EFA. Finally, the adhesive properties of crosslinked EFA on different substrates were evaluated.