Vitrimers are chemically crosslinked networks that can rearrange their topology without decreasing their crosslinking density thanks to exchangeable links present in the network. As a result, vitrimers can be reshaped and recycled at will, while displaying the superior properties of crosslinked polymers at service temperature. Very promising materials to create a circular economy of plastics and polymeric materials, vitrimers still display limitations that impact their transition towards industry, such as synthetic cost, high viscosity even at elevated temperatures, due to the Arrhenian temperature dependence of the melt viscosity, or moderate creep resistance at working temperatures in the case of low Tg materials.

Although many strategies have been reported to address these issues, it remains challenging to overcome a key tradeoff between improving the processability or the mechanical performance of vitrimers.

This lecture will present strategies that use phase separation to improve the processability and mechanical performance of dynamic polymer networks,^1-4 to upcycle polyolefin blends,⁵ or to create self-healing, injectable hydrogels.⁶

[1] Röttger, M.; Domenech, T.; van der Weegen, R.; Breuillac, A.; Nicolaÿ, R.; Leibler, L., High-performance vitrimers from commodity thermoplastics through dioxaborolane metathesis. Science 2017, 356, 62-65.
[2] Formon, G. J. M.; Storch, S.; Delplanque, A. Y. G.; Bresson, B.; Van Zee, N. J.; Nicolay, R., Overcoming the Tradeoff Between Processability and Mechanical Performance of Elastomeric Vitrimers. Adv. Funct. Mater. 2023, 33, 2306065.
[3] Quinteros-Sedano, A.; Bresson, B.; Van Zee, N. J.; Nicolay, R., Improving the Thermomechanical Properties and Processability of Elastomeric Vitrimers Using Thermoreversible Organic Nanofillers. ACS Mater. Lett. 2024, 6, 877-884.
[4] Formon, G. J. M.; Jayaratnam, J.; Guibert, C.; Van Zee, N. J.; Nicolay, R., Cross-Linking Vitrimers after Melt Processing Using Supramolecularly Masked Dynamic Cross-Linkers. Macromolecules 2024, 57, 8277-8286.
[5] Vialon, T.; Sun, H.; Formon, G. J. M.; Galanopoulo, P.; Guibert, C.; Averseng, F.; Rager, M.-N.; Percot, A.; Guillaneuf, Y.; Van Zee, N. J.; Nicolay, R., Upcycling Polyolefin Blends into High-Performance Materials by Exploiting Azidotriazine Chemistry Using Reactive Extrusion. J. Am. Chem. Soc. 2024, 146, 2673-2684.
[6] Sun, H.; Gode, I.; Bonnard, M.; Liautard, V.; Pomes-Hadda, M.; Aime, S.; Chabaud, L.; Edera, P.; Guerinot, A.; Pucheault, M.; Nicolay, R., Self-Healing and Creep-Resistant Injectable Hydrogel from Aminoborinate Chemistry and Phase Separation. ACS Mater. Lett. 2025, 7, 2534-2540.