Structure-Property Elucidation in Diketoenamine Vitrimers from Vinyl Polymers

Covalent adaptable networks (CANs) offer the (re)processability of thermoplastics while maintaining the thermomechanical robustness of thermosets. Specifically, associatively crosslinked networks, known as vitrimers, provide predictable flow behavior and a constant crosslink density at all temperatures due to the degenerative exchange mechanism of covalent crosslinking. In this study, we present the novel fabrication of diketoenamine vitrimers from vinyl pre-polymers through Reversible-Deactivation Radical Polymerization (RDRP) of innovative triketone-containing methacrylate monomers in combination with various commercial n-alkyl methacrylates. The triketone methacrylates exhibit rapid and well-controlled homopolymerization and copolymerization with statistical incorporation, resulting in narrow dispersities (Ð). We showcase the adjustability of the glass transition temperature (T_g) values, ranging between 17°C and 116°C, by facilely tuning the pendant length of the triketone monomer as well as the identity or feed ratio of the accompanying comonomer. This tunability translates to predictable T_g values and expected viscoelastic behavior within the resulting vitrimer networks. Moreover, the networks generated via catalyst-free diamine condensation exhibit remarkable creep resistance at elevated temperatures, along with both chemical and mechanical recyclability. Finally, we report the seminal synthesis of a vitrimer network from an ultra-high molecular weight (UHMW; >10⁶ g∙mol^-1) pre-polymer, which leads to a marked reduction of creep in comparison to its analogous low molecular weight networked pre-polymer. Our results establish the expansion of the attractive triketone motif into vitrimer networks from chain-growth polymers with facile tunability and topological control.