Novel Routes to Amphiphillic Ag Quantum Dots

Abstract

Quantum dots are nanometer-sized particles that contain a few thousand atoms. Individually they possess both quantum and classical properties due to their size, and ensembles of quantum dots also display novel properties. Our goal is to synthesize amphiphillic quantum dots that will assemble as finite numbered structures in solution. Silver quantum dots are created in both a one-phase and two-phase synthesis in chloroform or toluene, and are passivated by dodecanethiol. The quantum dots are refluxed to reduce polydispersity, and in addition the reflux step appears to further passivate the quantum dots making them much more resistant to ripening. The resultant quantum dots are approximately 7nm in diameter, as measured by Transmission Electron Microscopy, with good monodispersity and shelf life. Moreover, we are now able to alter the size, polydispersity, and monolayer packing density of the quantum dots by varying the synthesis slightly, allowing significant freedom in the creation of passivated silver quantum dots. After synthesis, the quantum dots are subjected to liquid-liquid extraction with 11-mercaptoundecanoic acid (MUA) dissolved in a water ethanol mixture. Under specific circumstances the quantum dots form an interfacial film at the boundary between the organic and aqueous phases. Our current research explores how the synthesis, particularly the reflux step, affects the formation of these interfacial films. Link to PowerPoint? presentation