(252d) Reverse Micelle Synthesis of Monodispersed Metallic Nanoparticles Via a Gas Expanded Liquid System

Monodispersity and size are important factors in the application of metallic nanoparticles, thus it is highly desirable to synthesize a monodisperse population of particles with a given diameter or utilize size-selective post synthesis processing methods to obtain a monodisperse particle population of a desired size. The tunable solvent properties of gas expanded liquids (GXLs) have been previously used to fractionate polydispersed populations of ligand-stabilized metal nanoparticles into distinct monodispersed fractions. We have employed GXLs in the synthesis of nanoparticles within AOT reverse micelles. The objective of this study is to answer two questions; 1.) can the pressure tunable properties of GXLs be used to control the size and  monodispersity of nanoparticle populations and 2.) what thermophysical parameters are controlling the nanoparticles size?  In the reverse micelle synthesis, the surfactant acts as a nanoscale reactor for nanoparticle synthesis as well as a stabilizing ligand for the synthesized particles.  Increasing the concentration of CO₂ in a GXL system (via. pressure) will affect the surfactant-solvent interaction, thus impacting the nanoparticle size and polydispersity.