Silver nanoparticle formation in microemulsions acting both as template and reducing agent
Silver nanoparticle formation in microemulsions acting both as template and reducing agent
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DOI：
10.1021/la050937j
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发表时间：
2005-11-22
期刊：
影响因子：
3.9
通讯作者：
Palmqvist, AEC
中科院分区：
文献类型：
--
作者：
Andersson, M;Pedersen, JS;Palmqvist, AEC
提出了一种在油包水微乳液中制备银纳米粒子的新方法，该方法使用表面活性剂作为还原剂和结构导向剂。由于没有使用外部强还原剂，形成的动力学是缓慢的，这使得可以原位研究银纳米颗粒的形成。所用的微乳液基于非离子表面活性剂Brij 30（C12 E4），其将银离子还原为金属银并由此被部分氧化，或者基于Brij 30和AOT（双（2-乙基己基）磺基琥珀酸钠）的混合物，其中后者不还原银离子。银离子和非离子表面活性剂浓度对纳米粒子的形成动力学的影响，随后在原位使用紫外-可见光谱，这两个参数被发现有很大的影响。通过小角X射线散射（SAXS）对微乳液液滴的尺寸、尺寸分布和形状进行了研究，并使用透射电子显微镜和SAXS对形成的银纳米颗粒进行了研究。小角X射线散射测量表明，硝酸银的存在并不影响微乳液体系显着，液滴的大小和形状保持在颗粒形成过程中。它示出的颗粒的大小和形态不直接遵循的微乳液液滴的形状和大小，即使有液滴的大小和所形成的颗粒的半径之间的关系。
A novel method of making silver nanoparticles in water-in-oil microemulsions using the surfactants as both the reducing agent and as the structure-directing agent is presented. Since no external strong reducing agent is used the kinetics of the formation is slow, which makes it possible to study the silver nanoparticle formation in situ. The microemulsions used were based on either the nonionic surfactant Brij30 (C12E4), which reduces the silver ion to metallic silver and is thereby partly oxidized, or mixtures of Brij30 and AOT (sodium bis(2-ethylhexyl) sulfosuccinate, where the latter does not reduce the silver ions. The influences of silver ion and nonionic surfactant concentrations on the formation kinetics of the nanoparticles were followed in situ using UV-vis spectroscopy, and both parameters were found to have a big influence. The microemulsion droplet's size, size distribution, and shape were examined by small-angle X-ray scattering (SAXS), and the formed silver nanoparticles were studied using both transmission electron microscopy and SAXS. The SAXS measurements showed that the presence of silver nitrate does not affect the microemulsion systems noticeably and that the droplet's size and shape are retained during the particle formation. It is shown that the size and morphology of the particles do not directly follow the shape and size of the microemulsion droplets even though there is a relation between the droplet size and the radii of the formed particles.