It is a challenge to develop adhesives simultaneously capable of strong adhesion and efficient switchable ability. Herein, the authors report multifunctional switchable adhesives named Cu²⁺-curcumin-imidazole-polyurethane (CIPUs:Cu²⁺) by introducing 1-(3-aminopropyl) imidazole and curcumin into polyurethane system crossed by Cu²⁺ forming dynamic metal-ligand bonds. This CIPUs:Cu²⁺ has strong adhesion (up to 2.46 MPa) on various material surfaces due to their specially designed functional groups alike the secretions from mussels. It can achieve fast switching speed (30 s) and high switch efficiency through multiple contactless remote stimulations. Importantly, density functional theory (DFT) calculation reveals that such metal-ligand bonds consisting of two components: stronger Cu²⁺-curcumin complexes and weaker Cu²⁺-imidazole complexes can aggregate to form multi-level dynamic stable structure . The special structure can not only be acted as sacrificial sites for easily broken and reformed, allowing efficient switchable adhesion and enormous energy dissipation but also acted as firm sites to maintain the cohesion of the adhesive and the reversible reconstruction network. Intriguingly, the CIPUs:Cu²⁺ can achieve self-healing at room temperature without needing external stimuli. Overall, this strategy can further broaden the design of switchable adhesives in the fields of intelligent gadgets, wearable bio-monitoring devices, etc.

中文翻译：

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基于多级动态稳定结构的自修复和可切换粘合剂的探索

开发同时具有强粘合力和高效可转换能力的粘合剂是一个挑战。在此，作者通过将1-(3-氨基丙基)咪唑和姜黄素引入到由Cu ²⁺交叉形成动态金属配体的聚氨酯体系中，报道了名为Cu ²⁺ -姜黄素-咪唑-聚氨酯(CIPUs:Cu ²⁺ )的多功能可转换粘合剂债券。本CIPU：Cu ²⁺由于其特殊设计的官能团类似于贻贝的分泌物，对各种材料表面具有很强的附着力（高达2.46 MPa）。通过多次非接触式远程刺激，可以实现快速切换（30秒）和高切换效率。重要的是，密度泛函理论（DFT）计算表明，这种金属-配体键由两种成分组成：较强的Cu ²⁺ -姜黄素络合物和较弱的Cu ²⁺咪唑配合物可以聚集形成多级动态稳定结构。这种特殊的结构不仅可以作为易断裂和重组的牺牲位点，实现高效的可切换粘附和巨大的能量耗散，而且可以作为维持粘合剂内聚力和可逆重建网络的牢固位点。有趣的是，CIPU:Cu ²⁺可以在室温下实现自修复，而不需要外部刺激。总体而言，该策略可以进一步拓宽可切换粘合剂在智能设备、可穿戴生物监测设备等领域的设计。