Dynamic Enamine-one Bond Based Vitrimer via Amino-yne Click Reaction

Abstract

Here, we report the fabrication of a dynamic enamine-one bond based vitrimer through amino-yne click chemistry. In contrast to amine-acetoacetate condensation, the amino-yne click reaction yields a dynamic enamine-one motif that is composed of cis/trans (3:1) isomers and has a relatively lower activation energy (35 ± 3 kJ/mol vs 59 ± 6 kJ/mol), owing to the absence of a methyl substituent. The resulting vitrimer network has superior mechanical properties and faster dynamic exchange than that of a reference vitrimer derived from amine-acetoacetate condensation, and they are attributed to the fewer network defects and the less sterically hindered exchange reaction, respectively. Lastly, the efficient amino-yne click reaction is demonstrated to be compatible with the secondary-amine substrate, which has a low reactivity toward the amine-acetoacetate condensation. The efficient and side product-free amino-yne reaction offers a powerful chemical tool for vitrimer fabrication and is potentially desirable for sealing and adhesion applications.

Relaxation of Vitrimers with Kinetically Distinct Mixed Dynamic Bonds

“…Developed over the past decade, vitrimers have been designed from many different chemistries and for many different applications. Vitrimers can provide an ideal platform for designing the viscoelastic properties of a polymer via changes in the chemistry of the polymer backbone − or the type of dynamic bond. ,− These materials have been investigated in applications including shockwave dissipation, three-dimensional (3D) printing, creep resistant plastics, thermally conductive materials, solid battery electrolytes, and ultrathin coatings, where the viscosity and modulus contribute substantially to the resultant performance. In most cases, vitrimers show an Arrhenius temperature dependence of viscosity and a storage modulus, which increases with the cross-link density. ,,, The modulus of vitrimers has also been shown to increase upon heating in contrast to most dissociative dynamic networks. ,, Through a combination of multiple dynamic bonds, the goal of precise control over the temperature-dependent viscoelasticity of a polymer may be possible.…”

Masked Primary Amines for a Controlled Plastic Flow of Vitrimers

“…In other words, the dicarboxamide motif served as a dynamic protecting group, facilitating the thermal release of the exchange enabling primary amines. 31 While fast transamination exchange within VU-based vitrimers is widely reported to critically rely on the presence of free primary amines, 7,25,32,33 stable adducts when reacted with acetoacetates, due to a lack of internal hydrogen bond stabilization in the resulting VU. 32 However, this general lack of nucleophilic reactivity might be drastically enhanced when a secondary amine group is present in close proximity to a normal VU cross-link.…”

Intra- vs Intermolecular Cross-Links in Poly(methyl methacrylate) Networks Containing Enamine Bonds

“…The remarkable similarities found above when comparing INTRA and INTER materials could be partially attributed to the dynamic character of the enamine cross-linking bonds, as demonstrated by the variety of vitrimers that have been prepared based on this “forgotten” dynamic covalent bond. Nevertheless, the clear differences in the broadness of the distribution characterizing the dynamic heterogeneities produced by cross-linking evidence that those materials prepared starting from the dilute solution of SCNP preserve a majority of intramolecular cross-links.…”