POSS Vitrimers: The Cage as a Dynamic Si–O–Si Node
Epoxy nanocomposite vitrimers containing polyhedral oligomeric silsesquioxane (POSS) were reported by Hongkun Yang, Changfei He, Thomas P. Russell, and Dong Wang in Giant in 2020. Studies devoted specifically to POSS in vitrimer networks remain scarce, and this one still carries the subject almost on its own. Glycidyl POSS was incorporated as a nanoscale filler into a transesterification-based epoxy, raising tensile strength and strain at break simultaneously while shifting the topology-freezing transition upward by more than 36 °C. A handful of related reports place silsesquioxane particles in other dynamic matrices, among them the bio-based polymethacrylate vitrimer nanocomposites of Hajiali, Tajbakhsh, and Marić, and in every case the cage serves as reinforcing filler. Key findings at a glance 10 wt% glycidyl POSS raises the ultimate tensile strength of a transesterification epoxy vitrimer from 21.9 to 35.8 MPa (+63.5%) and the strain at break from 190 to 334% (+75.8%). The topolog...