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Interfacial Layering of a Room‐Temperature Ionic Liquid Thin Film on Mica: A Computational Investigation
Author(s) -
Dragoni Daniele,
Manini Nicola,
Ballone Pietro
Publication year - 2012
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201100947
Subject(s) - mica , layering , ionic liquid , materials science , penetration (warfare) , mesoscopic physics , charge density , ionic bonding , molecular dynamics , thin film , ion , chemical physics , analytical chemistry (journal) , nanotechnology , chemistry , crystallography , condensed matter physics , computational chemistry , composite material , organic chemistry , physics , botany , operations research , quantum mechanics , engineering , biology , catalysis
The structure of a thin (4 nm) [bmim][Tf 2 N] film on mica was studied by molecular dynamics simulations using an empirical force field. Interfacial layering at T =300 K and at T =350 K is investigated by determining the number‐ and charge‐density profiles of [bmim][Tf 2 N] as a function of distance from mica, and by computing the normal force F z opposing the penetration of the ionic liquid film by a spherical nanometric tip interacting with [bmim][Tf 2 N] atoms by a short‐range potential. The results show that layering is important but localised within ∼1 nm from the interface. The addition of a surface charge on mica, globally neutralised by an opposite charge on the [bmim][Tf 2 N] side, gives rise to low‐amplitude charge oscillations extending through the entire film. However, outside a narrow interfacial region, the resistance of the [bmim][Tf 2 N] film to penetration by the mesoscopic tip is only marginally affected by the charge at the interface. The results obtained here for [bmim][Tf 2 N]/mica are similar to those obtained using the same method for the [bmim][Tf 2 N]/silica interface, and agree well with experimental force–distance profiles measured on the latter interface at ambient conditions.