Structure and Phase Behavior of Mixed Self-Assembled Alkanethiolate Monolayers on Gold Nanoparticles: A Monte Carlo Study

Evgenii O. Fetisov, J. Ilja Siepmann

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14 Scopus citations

Abstract

Configurational-bias Monte Carlo (CBMC) simulations are carried out to investigate the structure and phase behavior of self-assembled monolayers consisting of equimolar alkanethiolate mixtures chemisorbed on the surface of gold nanoparticles. The simulations probe the effects of variations in the chain length, nanoparticle curvature, and exchange of alkanethiolates between nanoparticles. The TraPPE-UA force field is used for the alkanethiolates, whereas the nanoparticle is represented by gold atoms placed on the surface of a sphere. CBMC identity exchange moves are used to enhance sampling of the spatial distribution of the different ligands and to ensure that thermodynamic equilibrium is reached. At a temperature of 298 K, mixtures differing in length by four methylene units exhibit some degree of local segregation. In contrast, the hexanethiolate/tetradecanethiolate mixture yields Janus-like arrangement when the ligands are confined to a single nanoparticle but global demixing when the ligands are allowed to distribute between two nanoparticles.

Original languageEnglish (US)
Pages (from-to)1972-1978
Number of pages7
JournalJournal of Physical Chemistry B
Volume120
Issue number8
DOIs
StatePublished - Mar 3 2016

Bibliographical note

Funding Information:
Financial support from the National Science Foundation (CHE-1152998) and computational resources from the Minnesota Supercomputing Institute are gratefully acknowledged.

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