Langmuir-Blodgett films of laurylamine-modified hydrophobic gold nanoparticles organized at the air-water interface

The organization of hydrophobized colloidal gold nanoparticles at air-water interface and the formation thereafter of lamellar, multilayer films of the gold nanoparticles by the Langmuir-Blodgett technique is described in this paper. The hydrophobization of the colloidal particles was accomplished by the direct chemisorption of laurylamine molecules on aqueous colloidal gold nanoparticles during a phase-transfer process. While monolayers of the laurylamine-capped gold nanoparticles at the air-water interface were not amenable to layer-by-layer transfer onto solid supports, it was observed that addition of the water-insoluble amphiphile octadecanol to the gold nanoparticle solution improved the stability of the monolayer at the interface as well as the multilayer assembly protocol. The organization of the gold nanoparticles at the air-water interface was followed by surface pressure-area isotherm measurements while the formation of multilayer films of the nanoparticles by the Langmuir-Blodgett technique was monitored by quartz crystal microgravimetry, UV-vis spectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy.