Epoxy-polyhedral oligomeric silsesquioxanes (POSS) nanocomposite vitrimers with high strength, toughness, and efficient relaxation

Although considerable progress has been made in developing vitrimers, on-going challenges for vitrimers for high-performance applications include the improvement in mechanical properties and identification of more efficient exchange reactions. By incorporation of glycidyl polyhedral oligomeric silsesquioxane (POSS) as a nanoscale filler in epoxy, we produced epoxy-POSS nanocomposite vitrimers that show high strength, toughness, thermal stability, and efficient relaxation. With 10 wt% POSS, the ultimate tensile strength and strain at break of the epoxy-POSS nanocomposite vitrimers increased by ~64% and ~76%, respectively, while at 160 °C the stress relaxation time increased by ~260% in comparison to that of pure epoxy vitrimer. The epoxy-POSS nanocomposite vitrimers show high malleability due to the efficient transesterification reaction and re-processability with little degradation of their initial mechanical properties, suggesting opportunities for sustainable plastics.