Two-Dimensional Arrays of Alkanethiol-Capped Gold : Analysis of Monolayer Formation Using a Langmuir Trough

Abstract

The structural dynamics of thin films of surfactant molecules can be characterized by their behavior in a Langmuir trough, where the molecules reside at the air-water interface. Parameters such as molecular order, film density, and surface pressure are easily addressed, and multilayer superstructures can be fabricated using this classic surface science strategy. Less common is the use of a Langmuir trough for the fabrication of organized two-dimensional arrays of alkanethiol-capped gold nanoparticles. Here, hydrophobic nanoparticles are introduced to the air-water interface as a solution in hexanes; as the solvent evaporates, the floating nanoparticles can be compressed into a monolayer within the Langmuir trough. Preliminary studies explored the relationship between film morphology and the length of the hydrocarbon chain, as well as changes in surface pressure as a function of aqueous subphase temperature.