Eugenol-based thermally stable thermosets by Alder-ene reaction: From synthesis to thermal degradation

Performing thermostable materials such as phenolic or epoxy networks are classically obtained from petrobased and harmful monomers. In this study, alternative solutions based on renewable eugenol trifunctional monomer (TEP) are proposed. Thus, innovative biobased Alder-ene thermosets are prepared by reacting TEP with two different bismaleimides: N,N'-1,3-phenylene bismaleimide (PhBMI) and polydimethylsiloxane bismaleimide (SiBMI) leading to different crosslinked aromatic networks. These materials exhibit various mechanical properties with very different T-g values of -113 degrees C and 247 degrees C for SiBMI and PhBMI materials respectively. However, both thermosets exhibit excellent thermal properties with elevated degradation temperature and high char yield. The degradation behavior was studied using thermogravimetric analysis - Fourier transformed infrared spectroscopy (TGA-FTIR): only silicon compounds were observed for SiBMI, whereas phosphorus and carbonaceous products had specific signatures in degradation gases for PhBMI. Kinetic analysis of degradation confirmed those different behaviors. Our contribution with two original Alder-ene thermosets is an innovative way to develop sustainable versatile high-performant materials.