A molecular dynamics study of CaCO3 nanoparticles in a hydrophobic solvent with a stearate co-surfactant.
File(s)
Accepted version
Author(s)
Bodnarchuk, MS
Heyes, DM
Breakspear, A
Chahine, S
Dini, D
Type
Journal Article
Abstract
Stearates containing overbased detergent nanoparticles (NPs) are used as acid neutralising additives in automotive and marine engine oils. Molecular dynamics (MD) simulations of the self-assembly of calcium carbonate, calcium stearate as a co-surfactant and stabilising surfactants of such NPs in a model explicit molecular hydrophobic solvent have been carried out using a methodology described first by Bodnarchuk et al. [J. Phys. Chem. C, 2014, 118, 21092]. The cores and particles as a whole become more elongated with stearate, and the surfactant molecules are more spaced out in this geometry than in their stearate-free counterparts. The rod dimensions are found to be largely independent of the surfactant type for a given amount of CaCO3. The corresponding particles without stearate were more spherical, the precise shape depending to a greater extent on the chemical architecture of the surfactant molecule. The rod-shaped stearate containing nanoparticles penetrated a model water droplet to a greater depth than the corresponding near-spherical particle, which is possibly facilitated by the dissociation of nanoparticle surfactant molecules onto the surface of the water in this process. These simulations are the first to corroborate the nanoparticle-water penetration mechanism proposed previously by experimental groups investigating the NP acid neutralisation characteristics.
Date Issued
2015-05-13
Date Acceptance
2015-04-22
Citation
Physical Chemistry Chemical Physics, 2015, 17 (20), pp.13575-13581
ISSN
1463-9084
Publisher
Royal Society of Chemistry
Start Page
13575
End Page
13581
Journal / Book Title
Physical Chemistry Chemical Physics
Volume
17
Issue
20
Copyright Statement
© The Royal Society of Chemistry 2015