Onion-like metal-organic colloidosomes from counterion-induced self-assembly of anionic surfactants
Onion-like metal-organic colloidosomes from counterion-induced self-assembly of anionic surfactants
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来自反离子诱导阴离子表面活性剂自组装的洋葱状金属有机胶体
DOI：
10.1039/c8ta04057e
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发表时间：
2018
影响因子：
11.9
通讯作者：
Sun Shi-Gang
中科院分区：
文献类型：
--
作者：
Zhou Yao;Chen Ji;e;Li Jun-Tao;Lin Zhi-Bin;Sun Shi-Gang
表面活性剂的胶束或囊泡虽然在材料合成中应用已久，但其演化组装行为及其作为模板在介观形貌控制中的作用尚待研究。然而，受限于其柔软和可变的性质，迄今为止纯胶束或囊泡的研究通常依赖于最先进的表征技术（例如，in situ原位ones）.在此，我们报道了阴离子表面活性剂SDBS的自组装行为受到过渡金属阳离子M2+（M = Co或Ni）（其作为阴离子DBS-的抗衡离子）在弱碱性环境中的存在的深刻影响。在良好控制的反应动力学下，容易形成具有亚稳定性的同心多壳M（OH）x（DBS）y胶体体。阴离子DBS-和不饱和阳离子[M（OH）x]y+物质之间的静电力以及DBS-分子尾部之间疏水相互作用产生的货车范德华力是组织整体结构的主要力。所观察到的胶体体一方面是足够稳定的，其可以从溶液中分离，并且可以方便地使用非原位技术如FESEM、TEM、XPS、FTIR和XRD来表征。另一方面，它们可以通过经典的奥斯特瓦尔德熟化过程灵活地演变成一系列层状或有壳的金属氢氧化物纳米结构，或者与另一种反应物反应以产生其他有壳的衍生物（例如，金属硅酸盐）。此外，简单热处理后的多壳胶体体及其衍生物也可作为析氧反应的有效电催化剂。这种洋葱状胶体体的易形成、方便表征和灵活转化强调了抗衡离子在调节离子表面活性剂自组装行为中的重要作用，从而构建了化学上难以实现的新型功能材料，也有助于材料合成中表面活性剂辅助形貌控制的机理研究。
Micelles or vesicles of surfactants, though being long utilized in material synthesis, are yet to be studied in terms of their evolutionary assembly behaviors and their role as a template in mesoscale morphology control. Nevertheless, restricted by their soft and changeable nature, so far investigations of pure micelles or vesicles often rely on state-of-the-art characterization techniques (e.g., in situ ones). Herein, we reported that the self-assembly behaviors of the anionic surfactant SDBS are profoundly affected by the presence of transition metal cations M2+ (M = Co or Ni) (which work as the counterion of the anionic DBS−) in a slightly alkaline environment. With well-controlled reaction kinetics, concentric multishelled M(OH)x(DBS)y colloidosomes are formed easily with meta-stability. The electrostatic forces between the anionic DBS− and the unsaturated cationic [M(OH)x]y+ species, and the van der Waals forces from the hydrophobic interaction among the DBS− molecular tails are the major forces organizing the overall structure. The as-observed colloidosomes on one hand are sufficiently stable which could be separated from the solution and characterized conveniently using ex situ techniques such as FESEM, TEM, XPS, FTIR and XRD. On the other hand, they could either evolve flexibly into a series of layered or shelled metal hydroxide nanostructures via the classical Ostwald ripening process, or react with another reactant to generate other shelled derivatives (e.g., metal silicates). The multishelled colloidosomes and their derivatives from simple thermal treatment were also explored as efficient electrocatalysts for the oxygen evolution reaction. The facile formation, the convenient characterization and the flexible transformation of such onion-like colloidosomes emphasize the important role of counterions in regulating the self-assembly behavior of ionic surfactants so as to construct novel functional materials that are thermodynamically difficult to achieve; they also contribute to a mechanistic study on surfactant-assisted morphology control in material synthesis.