Catalyst-Free α-Acetyl Cinnamate/Acetoacetate Exchange to Enable High Creep-Resistant Vitrimers

Vitrimers represent an emerging class of polymeric materials that combine the desirable characteristics of both thermoplastics and thermosets achieved through the design of dynamic covalent bonds within the polymer networks. However, these materials are prone to creep due to the inherent instability of dynamic covalent bonds. Consequently, there are pressing demands for the development of robust and stable dynamic covalent chemistries. Here, we report a catalyst-free alpha-acetyl cinnamate/acetoacetate (alpha-AC/A) exchange reaction to develop vitrimers with remarkable creep resistance. Small-molecule model studies revealed that the alpha-AC/A exchange occurred at temperatures above 140 degrees C in bulk, whereas at 120 degrees C, this reaction was absent. For demonstration in the case of polymers, copolymers derived from common vinyl monomers were crosslinked with terephthalaldehyde to produce alpha-AC/A vitrimers with tunable thermal and mechanical performance. All resulting alpha-AC/A vitrimers exhibited high stability, especially in terms of creep resistance at 120 degrees C, while retaining commendable reprocessability when subjected to high temperatures. This work showcases the alpha-AC/A exchange reaction as a novel and robust dynamic covalent chemistry capable of imparting both reprocessability and high stability to cross-linked networks.