It is very challenging to prepare elastomer vitrimers that are both robust and dimensionally stable in service. To address this issue, we have initiated a multi-phase design of elastomer vitrimers by incorporating quadruple hydrogen bonds (H-bonds) into vitrimer networks. Specifically, commercialized styrene–butadiene rubber (SBR) was functionalized with the synthesized 5-benzyl-3,6-dioxo-2-piperazineacetic acid (DKP) to introduce amide functionalities, which was then crosslinked by dimercapto-borate via thiol–ene “click” chemistry. The H-bonds between amide moieties functioned as sacrificial units, which could undergo reversible breakage and recombination events, and therefore improve the modulus, ultimate strength, and toughness simultaneously. Moreover, with an aromatic ring and a symmetrical amide group in the structure, the grafted DKP could self-assemble via hydrogen bonds, leading to the formation of a microphase-separated structure in the elastomer matrix. Besides, the creep resistance was improved as the H-bonds were physical crosslinks that imposed additional constraints on chain segment diffusion. Nevertheless, the reprocessability of the network was not affected as the H-bonds and boronic ester crosslinks could dissociate and exchange at elevated temperatures, respectively.

中文翻译：

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分子工程双交联弹性体玻璃体，具有卓越的强度、改进的抗蠕变性和保留的延展性

制备坚固且在使用中尺寸稳定的弹性体玻璃体非常具有挑战性。为了解决这个问题，我们通过将四重氢键 (H-bonds) 结合到 vitrimer 网络中，开始了弹性体 vitrimer 的多相设计。具体来说，商业化的丁苯橡胶 (SBR) 用合成的 5-benzyl-3,6-dioxo-2-piperazine acetate (DKP) 官能化以引入酰胺官能团，然后通过二巯基硼酸酯交联硫醇-烯“点击”化学。酰胺部分之​​间的氢键作为牺牲单元，可以发生可逆的断裂和重组事件，从而同时提高模量、极限强度和韧性。此外，结构中具有芳环和对称的酰胺基团，接枝的DKP可以通过氢键自组装，从而在弹性体基体中形成微相分离结构。此外，由于氢键是物理交联，对链段扩散施加了额外的限制，因此抗蠕变性得到了改善。然而，网络的可再加工性没有受到影响，因为 H 键和硼酸酯交联可以分别在高温下解离和交换。