Jiang Julong, Wang Zhi Jian, Staub Ruben, Harabuchi Yu, Varnek Alexandre, Gong Jian Ping, Maeda Satoshi
Institute for Chemical Reaction Design and Discovery (WPI-ICReDD), Hokkaido University Kita 21, Nishi 10, Kita-ku Sapporo Hokkaido 001-0021 Japan
Laboratory of Chemoinformatics, UMR 7140, CNRS, University of Strasbourg 67081 Strasbourg France.
Chem Sci. 2025 Jul 10. doi: 10.1039/d5sc00151j.
Mechanophores are force-sensitive compounds that undergo chemical reactions under force stimuli. The design and discovery of efficient yet thermally stable mechanophores are crucial for developing self-strengthening materials. However, conventional mechanophores are often chemically unstable due to the presence of highly strained rings or weak covalent bonds, making the material sensitive to the change of temperature or UV irradiation. In this study, a comprehensive computational exploration was conducted to discover thermally stable, unconventional mechanophores for self-strengthening materials based on mechanoradical polymerisation. Notably, the computational procedure presented here serves as a general strategy for designing mechanophores intended for various applications. First, a conformational motif called a "node" along the force transduction direction was identified, significantly enhancing the force effect. Molecules with bridged rings emerged as ideal candidates for possessing a "node," as the bridged structure helps to fix the key dihedral angle. Simulations predicted that polymers containing camphanediol and pinanediol could readily undergo C-C bond homolysis under force. Subsequently, automated reaction path exploration revealed the fate of the mechanoradicals and suggested that camphanediol could generate long-lived radicals, a crucial feature for self-strengthening materials. Following these computational predictions, we successfully prepared double-network hydrogels containing the camphanediol moiety. Careful experiments were then performed to quantify the concentration of mechanoradicals, and enhanced self-strengthening performance was demonstrated through loading-unloading tests.
力敏团是一类在力刺激下会发生化学反应的力敏化合物。设计并发现高效且热稳定的力敏团对于开发自增强材料至关重要。然而，传统的力敏团由于存在高张力环或弱共价键，往往化学性质不稳定，这使得材料对温度变化或紫外线照射敏感。在本研究中，我们进行了全面的计算探索，以发现基于机械自由基聚合的用于自增强材料的热稳定、非传统力敏团。值得注意的是，这里提出的计算程序是设计用于各种应用的力敏团的通用策略。首先，确定了沿力传递方向的一种称为“节点”的构象基序，显著增强了力效应。具有桥环的分子成为具有“节点”的理想候选者，因为桥接结构有助于固定关键二面角。模拟预测，含有莰二醇和蒎二醇的聚合物在力作用下容易发生C-C键均裂。随后，自动反应路径探索揭示了机械自由基的命运，并表明莰二醇可以产生长寿命自由基，这是自增强材料的关键特征。根据这些计算预测，我们成功制备了含有莰二醇部分的双网络水凝胶。然后进行了仔细的实验以量化机械自由基的浓度，并通过加载-卸载测试证明了增强的自增强性能。
