Wang, S., Feng, H., Li, B., Lim, J. Y. C., Rusli, W., Zhu, J., Hadjichristidis, N., & Li, Z. (2024). Knoevenagel C═C Metathesis Enabled Glassy Vitrimers with High Rigidity, Toughness, and Malleability. Journal of the American Chemical Society, 146(23), 16112–16118. https://doi.org/10.1021/jacs.4c03503
Abstract:
Thermosets, characterized by their three-dimensional crosslinked networks, present significant challenges in recyclability and brittleness. In this work, we explore a polarized Knoevenagel C=C metathesis reaction for the development of rigid yet tough and malleable thermosets. Initial investigation on small model molecules reveals the feasibility of conducting the base-catalyzed C=C metathesis reaction in a solvent-free environment. Subsequently, thermosetting poly(α-cyanocinnamate)s (PCCs) were synthesized via Knoevenagel condensation between a tri-arm cyanoacetate star and a dialdehyde. The thermal and mechanical properties of the developed PCCs can be easily modulated by altering the structure of the dialdehyde. Remarkably, the introduction of ether groups into the PCC led to an unprecedented combination of rigidity and toughness with a Young’s modulus of ~1590 MPa, an elongation at break of ~79%, and a toughness reaching ~30 MJ/m-3. These values are competitive to traditional thermosets including epoxy resins and polyimides, in modulus, but far exceed them in ductility and toughness. Moreover, the C=C metathesis facilitates stress relaxation within the bulk polymer networks, thus rendering PCCs excellent malleability and processability. This work overcomes the traditional limitations of thermosets, introducing groundbreaking insights for the design of rigid yet tough/malleable thermosets, and contributing significantly to the sustainability of materials.
License type:
Attribution 4.0 International (CC BY 4.0)
Funding Info:
This research / project is supported by the Agency for Science, Technology and Research (A*STAR) - RIE2025 Manufacturing, Trade and Connectivity (MTC) Programmatic Funding
Grant Reference no. : M22K9b0049
This research / project is supported by the Agency for Science, Technology and Research (A*STAR) - AME Young Individual Research Grants (YIRG)
Grant Reference no. : M22K3c0103
This research / project is supported by the Agency for Science, Technology and Research (A*STAR) - A*STAR Career Development Fund
Grant Reference no. : C222812032