纳米银的合成与表征——三种微乳体系的比较研究

Synthesis and Characterization of Silver Nanoparticles: A Comparison Study of Three Microemulsion Systems

摘要:

利用SDS-环己烷-异辛醇-水、AOT-环己烷-水和AOT-十二烷-水等3种微乳体系分别制备纳米银溶胶，利用紫外-可见光谱和透射电镜对形成粒子进行表征，进而探讨纳米银粒子的形成机制。3种体系中纳米银的共振吸收强度依次减小，半峰宽依次增大，最大吸收波长分别为400，428和435 nm；形成粒子均为球形结构，无团聚现象，但粒子的平均粒度和粒度分布存在明显的差异；3种体系中形成粒子的平均粒度分别为6.46，4.03和1.78 nm。微乳体系中球形胶束为纳米银的形成提供一种独特的微观环境，但由于碰撞导致团聚，微

Abstract:

Colloidal silver nanoparticles were synthesized respectively in three water-in-oil microemulsions, i.e., the microemulsion composed of SDS, cyclohexane, isoamylalcohol and water, the microemulsion composed of AOT, cyclohexane and water as well as the microemulsion composed of AOT, dodecane and water. The UV-Vis absorption spectroscopy was used for confirming the formation of silver nanoparticles, and the TEM was also used for elucidating the structure of resultant particles. The UV-Vis spectra show that the maxima of absorption peaks are at 400 nm, 428 nm and 435 nm, respectively. The UV-Vis spectrum is narrow with a high absorption density in SDS microemulsion. However, the silver particles formed in AOT-dodecane-water microemulsion have the broadest plasmon peak and the lowest absorption density. The TEM images confirm that the nanoparticles are all spherical with mean diameters of 6.46 nm, 4.03 nm, and 1.78 nm, respectively. There are not agglomerated particles in the three microemulsions. The growth mechanism of spherical silver particles is thought to be that the spherical reverse micelles in microemulsions offer a special microscopic template for the formation of silver namoparticles, and thus there is a relation between the droplet size and the radii of the formed particles. However, the size and morphology of the particles do not directly follow the shape and size of the microemulsion droplets due to the collision and coalescence. That is to say, the final silver nanoparticles are not perfectly monodisperse and have a breadth in size distribution