Bioinspired design of elastomeric vitrimers with sacrificial metal-ligand
interactions leading to supramechanical robustness and
retentive malleability

Siwu Wu, Shifeng Fang, Zhenghai Tang, Fang Liu and Baochun Guo⁎

ABSTRACT: Most elastomeric vitrimers suffer from mechanical weakness in practical applications. Inspired by the development of strong and tough biomaterials relying on sacrificial bond-detachment mechanisms, herein we describe the biomimetic design of elastomeric vitrimers with mechanical robustness, preservable malleability, and recyclability by engineering sacrificial metal-ligand coordination bonds into exchangeable networks. In particular, we use a commercially available metal complex, aluminum acetylacetonate (Al(acac)₃), to catalyze crosslinking based on the silylation reaction between hydroxylated natural rubber and hydrosilanes, thus introducing dynamic silyl ether-based architectures into the rubber matrix. At the same time, the Al³⁺ ions can interact with the free oxygen-containing moieties on the rubber skeleton, enabling labile Al³⁺-O coordination bonds in the covalent framework to substantially dissipate mechanical energy through reversible bond detachment/reattachment upon deformation. As the organic acetylacetonate ligands of Al(acac)₃ can facilitate the dispersion of Al³⁺-O ions in the matrix, incorporating a small amount of organometallic complex (0.68 wt% of elastomer matrix) achieves an unparalleled improvement of the strength, modulus, and toughness of the resulting vitrimers. Moreover, due to their temperature-dependent nature, the Al³⁺-O coordination bonds will partially dissociate at elevated temperatures, which only slightly compromises the topological rearrangements of the silyl ether-based network, but barely affects the reprocessability.

文章链接：https://doi.org/10.1016/j.matdes.2020.108756