Layer-by-layer Self-Assembly of Colloidal Gold-Silica Multilayers

TCE

The Chemical Educator

ISSN: 1430-4171 (electronic version)

Table of Contents

Abstract Volume 13 Issue 3 (2008) pp 153-157

Layer-by-layer Self-Assembly of Colloidal Gold-Silica Multilayers

Zhenyuan Zhang, Dan Meisel, Prashant Kamat, Masaru Kuno*

Department of Chemistry and Biochemistry, Notre Dame Radiation Laboratory, University of Notre Dame, Notre Dame, IN 46556, mkuno@nd.edu
Received August 1, 2007. Accepted March 24, 2008.

Published online: 1 June 2008

Abstract. Strategies to obtain self-assembled monolayers (SAMs) of molecular entities as well as the underlying chemical principles leading to their formation have been described in the Journal. Here we adopt similar principles to self-assemble monolayers of gold nanoparticles (NPs) in a layer-by-layer fashion. The gold particles provide the functionality of component atoms in what would otherwise constitute a conventional lattice. Several successive Au NP monolayers, each separated by a silica layer, are then added to create a three dimensional (3D) multilayer. During the assembly, the student tests the effect of the medium’s dielectric constant on the extinction spectrum of individual NP monolayers. Shifts in the plasmon band peak position illustrate the control one has over the optical and electrical properties of the 3D structure. Next, the student demonstrates through additional extinction measurements that no more than one Au NP monolayer is deposited at each step of the assembly when reaction conditions are judiciously chosen. Variations in the layer-by-layer deposition conditions may then be attempted to directly modify the extinction of the final structure. The entire experiment illustrates the construction of 3D assemblies of nanostructured materials whose intralayer- and interlayer- interparticle electronic and spectroscopic interactions can be controlled.

Key Words: Laboratories and Demonstrations; analytical chemistry; physical chemistry; hands-on learning/manipulatives; colloids; materials science; nanotechnology; surface science; synthesis; UV/vis spectroscopy

(*) Corresponding author. (E-mail: mkuno@nd.edu)

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Supporting Materials:

Supporting information describing the sequence of steps followed in the class and laboratory is available (42 KB).