Infrared external reflection spectra of Janus gold nanoparticle monolayers prepared at the air–water interface

H Sakai,T Kawai,A Matsuzawa

doi:10.1051/matecconf/20179801005

Abstract

Abstract. Nanoparticle monolayers at the air–water interface have received broad attention because of their potential applications owing to the tunability of their surface properties. We prepared gold nanoparticle monolayers by adsorption of hydrophilized nanoparticles from solution onto Langmuir monolayers of amphiphilic organic molecules (polyion complexes of deuterated stearic acid and polyallylamine) at the air–water interface, followed by adsorption of dodecyltrimethylammonium bromide onto the underside of these particles. The infrared external reflection spectra of the monolayers recorded both during and after preparation showed that the adsorption of gold nanoparticles on the Langmuir monolayers and that of dodecyltrimethylammonium bromide on the nanoparticles occurred in several tens of minutes. The infrared spectra also showed that both stearic acid and dodecyltrimethylammonium bromide molecules were highly ordered on the gold nanoparticles at the air–water interface. These results suggested that this preparation procedure is a useful fabrication method for Janus particles.

Highlights

The construction of 2D arrays of nanoparticles (NPs) is of great importance owing to their potential applications in electronic, magnetic, and optical devices [1,2,3]
AuNP monolayers prepared by adsorption of hydrophilized AuNPs from solution onto Langmuir monolayers of amphiphilic organic molecules at the air–water interface have not been examined in as much detail as those prepared by spreading highly hydrophobized NPs over the air–water interface
The preparation method involving hydrophilized AuNPs allows for the fabrication of Janus particles through the addition of different ligands to the underside of particles partially covered with molecules in the Langmuir monolayer

Summary

Introduction

The construction of 2D arrays of nanoparticles (NPs) is of great importance owing to their potential applications in electronic, magnetic, and optical devices [1,2,3]. The preparation method involving hydrophilized AuNPs allows for the fabrication of Janus particles through the addition of different ligands to the underside of particles partially covered with molecules in the Langmuir monolayer. This method has the advantage of using little organic solvent during the fabrication of Janus particles. It is important to determine the adsorption kinetics and the structural arrangement of the ligands on the nanoparticles prepared using this method. We prepared AuNP monolayers covered with dodecyltrimethylammonium bromide (DTAB) and Langmuir monolayers of polyion complexes of deuterated stearic acid (d-STA) and polyallylamine (PAA) at the air–water interface (Figure 1). We observed the adsorption of the molecules on the nanoparticles during the preparation process

Materials

Preparation Method

Results and Discussion

Conclusions