In a previous contribution we described the formation of silica nanostructures in dye-stabilized nanoemulsions from tetraethyl orthosilicate droplets in water. Depending on the type of dye, either capsules (crystal violet, CV) or nanoparticles (congo red, CR) are formed. The thorough study of the sol–gel process uses a combination of time- and/or temperature-resolved small-angle X-ray scattering, transmission electron microscopy, and ¹H NMR spectroscopy to elucidate the detailed kinetics and mechanism of structure formation. In both cases, small nuclei of 1.5–2 nm are formed, followed by either a fast cluster–cluster (CV) or a much slower monomer–cluster aggregation (CR). The former leads to a cross-linked network and finally to patchy capsules, while the latter leads to individual nanoparticles (SNPs). From an Avrami plot it can be deduced that the SNPs are formed by an interface-controlled one-dimensional growth process. The mechanisms are based on the different local environments at the oil–water interface, which is either slightly acidic (CV) or fairly basic (CR). The kinetics differ by a factor between 3 and 20 and are presumably caused by the different mobility of the catalyzing species H⁺ or OH^–.

中文翻译：

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染料稳定乳液油水界面 SiO2 颗粒和胶囊形成机理的研究

在先前的贡献中，我们描述了在水中由原硅酸四乙酯液滴在染料稳定的纳米乳液中形成二氧化硅纳米结构。根据染料的类型，形成胶囊（结晶紫，CV）或纳米颗粒（刚果红，CR）。溶胶-凝胶过程的彻底研究结合了时间和/或温度分辨小角 X 射线散射、透射电子显微镜和¹H NMR光谱阐明结构形成的详细动力学和机制。在这两种情况下，都会形成 1.5-2 nm 的小核，然后是快速的簇 - 簇 (CV) 或慢得多的单体 - 簇聚集 (CR)。前者导致交联网络，最后导致不完整的胶囊，而后者导致单个纳米颗粒（SNP）。从 Avrami 图可以推断出 SNP 是由界面控制的一维生长过程形成的。这些机制基于油水界面的不同局部环境，要么是微酸性（CV），要么是相当碱性（CR）。动力学相差 3 到 20 倍，可能是由催化物质 H ⁺或 OH ^-的不同迁移率引起的。