Ultra-stretchable and Self-Healable Vitrimers with Tuneable Damping and Mechanical Response

Abstract: Vitrimers are a relatively new class of polymer materials with unique properties offered by cross-links that can undergo associative exchange dynamics. We here present a new class of vitrimers based on poly(methyl acrylate) with cross-links utilising dioxaboralane metathesis. These vitrimers demonstrate a combination of ultra-stretchability (up to $\sim$ 80 times their own length), mechanical toughness ($\sim$ 40 MJ/m$^3$), and thermal stability up to $T\sim$ 250 {\deg}C; moreover, the vitrimers demonstrate excellent mechanical damping characterised by a loss factor ($\tan(\delta)$) with a maximum of $\sim$ 2-3 and an effective value $>$0.3 across five decades in frequency (0.001-100 Hz), or correspondingly across a $T$-range of $\sim$ 35 {\deg}C near room temperature (for a probe frequency of 1 Hz). The vitrimers can be successfully re-processed using both a thermo-mechanical and a chemical processing route, and can self-heal at room temperature, making them suitable for sustainable applications. The material properties are directly tuneable by variation of both the amount of cross-linker and by the degree of curing. Thus, this class of vitrimers are promising for applications where stretchability combined with mechanical toughness and/or a high mechanical dissipation is required.