近日，山东大学魏璟婧团队实现了用粘性纳米线分散体提高反应动力学。这一研究成果于2025年4月22日发表在《美国化学会杂志》上。

较高的粘度通常通过限制分子运动来减缓化学反应，而搅拌通过增强反应物扩散和碰撞来加速反应。然而，研究组发现纳米线分散体中的反应速率——微观粘度约为癸烷的300倍——可以提高一个数量级以上。与直觉相反，搅拌会减缓反应，更高的搅拌速率会导致更大的减速。这种现象在光活化和热活化的循环反应中都有观察到。

分子动力学模拟和共聚焦激光扫描显微镜表明，接枝到纳米线上的脂肪链与各向异性分子相互作用，增加了纳米线附近的局部浓度。值得注意的是，尽管在没有纳米线的情况下在30秒内完成，但偶氮苯光异构化在纳米线分散体中完全被抑制。研究组提出，脂肪链使反应分子定向排列，而有限的空间防止了大量顺式异构体的形成。这些发现表明，纳米线不仅能捕获和定向反应分子，还能排除大块产物，显著增强受限系统中的反应动力学。

附：英文原文

Title: Boosting Reaction Kinetics with Viscous Nanowire Dispersions

Author: Jurong Dong, Hongkun Cao, Zhiwei Yang, Zongze Zhang, Zhijie Yang, Lingxiang Jiang, Jingjing Wei

Issue&Volume: April 22, 2025

Abstract: Higher viscosity typically slows chemical reactions by restricting molecular movement, while stirring accelerates reactions by enhancing reactant diffusion and collisions. However, in this study, we reveal that reaction rates in nanowire dispersions─with microscopic viscosity ～300 times that of decane, can be enhanced by over an order of magnitude. Counterintuitively, stirring slows the reaction with higher stirring rates causing even greater deceleration. This phenomenon is observed in both photo- and thermally activated cyclic reactions. Molecular dynamics simulations and confocal laser scanning microscopy suggest that aliphatic chains grafted onto nanowires interact with anisotropic molecules, increasing their local concentrations near the nanowires. Notably, azobenzene photoisomerization is completely inhibited in the nanowire dispersion, despite completing within 30 s in the absence of nanowires. We propose that the aliphatic chains align reactive molecules directionally, while the confined space prevents bulky cis-isomer formation. These findings show that nanowires not only harvest and orient reactive molecules but also exclude bulky products, significantly enhancing the reaction kinetics in confined systems.

DOI: 10.1021/jacs.5c02034

Source: https://pubs.acs.org/doi/abs/10.1021/jacs.5c02034