Harada Masafumi, Yamamoto Miho, Iwase Hiroki
Department of Computer Science and Clothing Environment, Faculty of Human Life and Environment, Nara Women's University, Nara 630-8506, Japan.
Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society (CROSS), 162-1 Shirakata, Tokai, Ibaraki 319-1106, Japan.
Langmuir. 2021 Nov 9;37(44):13085-13098. doi: 10.1021/acs.langmuir.1c02235. Epub 2021 Oct 29.
In this study, we used small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS) to investigate the formation process of silver (Ag) nanoparticles (NPs) in water-in-oil (w/o) reverse microemulsions comprising sodium bis(2-ethylhexyl) sulfosuccinate (AOT), water, and organic solvents (such as benzene, octane, and decane) by the photoreduction of silver perchlorate (AgClO). Combining SANS and SAXS, the structural changes in the w/o microemulsions before and after the formation of Ag NPs via photoreduction were quantitatively evaluated. From the SANS experiments performed using the contrast-variation method, the size of water cores containing Ag NPs and the thickness of the AOT shells were calculated using the core-shell hard-sphere model. The size of the Ag NPs and their aggregates was calculated via SAXS analysis based on the polydisperse sphere model with a Schulz-Zimm distribution. We found that aggregates of three or four primary Ag NPs are formed by, first, the aggregation of water droplets through the entanglement of the tails of the AOT shell, followed by the self-assembly of Ag NPs into their aggregates because of particle-particle attractive interactions.
在本研究中，我们使用小角中子散射（SANS）和小角X射线散射（SAXS）来研究通过高氯酸银（AgClO）的光还原作用，在由双（2-乙基己基）磺基琥珀酸钠（AOT）、水和有机溶剂（如苯、辛烷和癸烷）组成的油包水（w/o）反相微乳液中银（Ag）纳米颗粒（NPs）的形成过程。结合SANS和SAXS，对通过光还原形成Ag NPs前后w/o微乳液的结构变化进行了定量评估。通过使用对比变化法进行的SANS实验，利用核壳硬球模型计算了含有Ag NPs的水核尺寸和AOT壳层的厚度。基于具有舒尔茨-齐姆分布的多分散球模型，通过SAXS分析计算了Ag NPs及其聚集体的尺寸。我们发现，首先，通过AOT壳层尾部的缠结使水滴聚集，然后由于颗粒间的吸引相互作用，Ag NPs自组装成其聚集体，从而形成由三个或四个初级Ag NPs组成的聚集体。
