The influence of fractional surface coverage on the core–core separation in ordered monolayers of thiol-ligated Au nanoparticles. Issue 43 (10th October 2019)

• Record Type: Journal Article
• Authors: Reik, Morgan; Calabro, Melanie; Griesemer, Sean; Barry, Edward; Bu, Wei; Lin, Binhua; Rice, Stuart A.
• Is Part Of: Soft matter. Volume 15:Issue 43(2019)
• Page Start: 8800
• Page End: 8807
• Publication Date: 2019-10-10
• Subjects: Soft condensed matter -- Periodicals; 530.413
• DOI: 10.1039/c9sm01579e
• Languages: English
• ISSNs: 1744-683X

Abstract

Abstract : This study examines the way in which fractional surface coverage on a nanoparticle surface affects nanoparticle interactions and the long-range order of Langmuir monolayers. Abstract : We report the results of grazing incidence X-ray diffraction (GIXD) measurements from water supported Langmuir monolayers of gold nanoparticles ligated with dodecanethiol (12 carbons), tetradecanethiol (14 carbons), hexadecanethiol (16 carbons), and octadecanethiol (18 carbons). These monolayers are formed from solutions with varying concentrations of the respective thiols. We show that equilibrium between adsorbed thiol molecules and the thiols in the bulk solution implies fractional coverage of the Au nanoparticle core. We also show that the nanoparticle–nanoparticle separation and the correlation length of particles in these ordered films increases with thiol concentration in the parent solution, and that excess thiol can be found in the space between particles as well as in islands away from the particles. Using the equilibrium constant relating ligand solution concentration and nanoparticle surface coverage of the gold core by the ligand molecules, we interpret the way in which varying thiol concentration affects the nanoparticle–nanoparticle separation as a function of surface coverage of the gold core by the ligand molecules.