Effect of amino, hydroxyl, and carboxyl terminal groups of alkyl chains of self‐assembled monolayers on the adsorption pattern of gold nanoparticles

Abstract

The adsorption pattern of gold nanoparticles (AuNPs) on functionalized self‐assembled monolayers (SAMs) produced on a Au(111) surface was characterized. The Au(111) was modified with 11‐amino‐1‐undecanethiol hydrochloride (AUT), 11‐mercapto‐1‐undecanol (MUT), or 11‐mercaptoundecanoic acid (MUA) at an elevated temperature and pressure. The AuNPs aggregated on the AUT‐SAM surface, whereas they were well dispersed on the MUT‐SAM surface and localized on the MUA‐SAM surface. The results suggest that interactions between AuNPs differ according to the degree of peeling of citrate‐layer‐capped AuNPs. The degree of peeling, which is related to both the surface randomness of the SAMs and the functional characteristics of the terminal group of each SAM, was discussed on the basis of scanning tunneling microscopy observations, X‐ray photoelectron spectroscopic analyses, and contact angle measurements. Our study shows that AuNP patterns can be controlled by changing the terminal group of the alkyl thiol SAM on a Au(111) surface.