Structural patterns and molecular mobility inside the interface between an fcc solid and liquid n-octane

Koopman, David C.; Gupta, Sachchidanand Soaham; Ballamudi, Ravi K.; Westermann-Clark, G.B.; Bitsanis, Ioannis A.

doi:10.1016/0009-2509(94)e0109-4

Cited by 16 publications

(15 citation statements)

References 44 publications

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“…b͒ Electronic mail: khassl@ford.com tane, octane, and dodecane on ␣-Al 2 O 3 (0001) at a variety of temperatures. As in previous simulations of liquid alkanes on Au, 21,24,25 graphite, 26 and model 27,28 solid surfaces, we see strong layering effects and other significant changes in static and dynamic properties compared to bulk alkanes. We next briefly consider what happens when a cluster of 30 water molecules approaches a bare ␣-Al 2 O 3 (0001) surface, assuming that any water molecules that reach the surface remain intact.…”

Section: Introductionsupporting

confidence: 84%

Simulations of hydrocarbon adsorption and subsequent water penetration on an aluminum oxide surface

Claire

Hass

Schneider

et al. 1997

The Journal of Chemical Physics

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International audienceStatic and dynamic equilibrium properties of butane octane, and dodecane films adsorbed on α-Al2O3(0001) at a variety of coverages and temperatures, and the subsequent penetration of such films by 30 molecule water clusters are examined using classical molecular dynamics. Model potential functions are constructed from existing alkane united atom and "simple point charge" model water parameters, experimental alkane desorption energies and other available theoretical information. The adsorbed films exhibit a distinct layering parallel to the surface, and a pronounced densification, reduction in gauche defects and orientational ordering within the innermost layer. Strong surface corrugation allows molecules to rotate relatively freely about their long axes at intermediate temperatures and assists them in orienting their zig-zag planes perpendicular to the surface at lower temperatures. Only butane molecules show any tendency to tilt their long axes out of the first layer toward the second. (H2O)30 clusters are attracted toward the alumina surface and easily penetrate most of the adsorbed alkane films, either by displacing alkane molecules to more distant layers or causing them to pack more closely within existing layers. The molecules in the clusters tend to remain connected during penetration. Kinetic barriers to penetration become increasingly significant for higher alkane coverages, lower temperatures, and longer chains

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Section: Introductionsupporting

confidence: 84%

Simulations of hydrocarbon adsorption and subsequent water penetration on an aluminum oxide surface

Claire

Hass

Schneider

et al. 1997

The Journal of Chemical Physics

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“…Nevertheless, partial crystallization and amorphous-crystal 49,50 This observation agrees with Pusey's experiments which show that solutions with size dispersity higher than 7.5% freeze partially, while those with size dispersity around 12% do not. DFT studies 51,52 that refer to a terminal size dispersity of around 5%-7% are also in agreement with our results, considering the fact that in these studies the constrained eutectic model, 52 which does not allow fractionization, was employed.…”

Section: Resultssupporting

confidence: 90%

Phase equilibrium of colloidal suspensions with particle size dispersity: A Monte Carlo study

Yiannourakou

Economou

Bitsanis

2009

The Journal of Chemical Physics

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We have studied the crystalline-amorphous coexistence for systems of polydisperse soft spheres that interact via a purely repulsive power law potential. Potential softness quantified by the exponent of the potential was a primary input in our simulations. Simulations were performed in the isobaric semigrand statistical ensemble, i.e., the composition of the parent distribution was not fixed in our systems. Gibbs-Duhem integration was used to trace the coexistence pressure as a function of potential softness for monodisperse systems. A second Gibbs-Duhem integration, initiated from the monodisperse coexistence curve, was employed to determine coexistence pressure versus imposed variance of the activity distribution. Amorphous-crystalline coexistence densities and volume fractions were determined to be monotonically increasing functions of the breadth of particle size dispersity. Semigrand ensemble simulations testified to the existence of a terminal diameter dispersity, i.e., a dispersity above which no amorphous-crystalline phase coexistence was observed. At the terminus size dispersity increases from 5.8% to 6.1% to 6.4% and to 6.7% and 6.5% for the crystalline phase as the steepness parameter n, takes on smaller values: from 100 to 50 to 12 to 10 and 8, respectively. In sharp contrast to the crystalline phases' enhanced, by potential softness, allowable size dispersity the amorphous phase exhibits an opposite trend, as potential interactions soften. Furthermore, amorphous phases accommodate, on average, smaller particles than those of the ordered (fcc) phase. Contrary to widely accepted intuition crystalline phases composed of size-disperse particulates exhibit a higher degree of local order than their monodisperse counterparts, admittedly at differing thermodynamic conditions.

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“…In particular, under different conditions of pressure, density and wall symmetry, the confinement could lead to 'solidification' near the surfaces, manifested by the existence of domains with crystalline ordering [32]. In these systems shear may affect the structure of these domains resulting in a destruction of their crystallinity, thus causing the melting of these 'microcrystallines'.…”

Section: Resultsmentioning

confidence: 99%

Adsorption-desorption kinetics in nanoscopically confined oligomer films under shear

et al. 1995

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The method of molecular dynamics computer simulations is employed to study oligomer melts confined in ultra-thin films and subjected to shear. The focus is on the self-diffusion of oligomers near attractive surfaces and on their desorption, together with the effects of increasing energy of adsorption and shear. It is found that the mobility of the oligomers near an attractive surface is strongly decreased. Moreover, although shearing the system forces the chains to stretch parallel to the surfaces and thus increase the energy of adsorption per chain, flow also promotes desorption. The study of chain desorption kinetics reveals the molecular processes responsible for the enhancement of desorption under shear. They involve sequences of conformations starting with a desorbed tail and proceeding in a very fast, correlated, segment-by-segment manner to the desorption of the oligomers from the surfaces.

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Structural patterns and molecular mobility inside the interface between an fcc solid and liquid n-octane

Cited by 16 publications

References 44 publications

Simulations of hydrocarbon adsorption and subsequent water penetration on an aluminum oxide surface

Simulations of hydrocarbon adsorption and subsequent water penetration on an aluminum oxide surface

Phase equilibrium of colloidal suspensions with particle size dispersity: A Monte Carlo study

Adsorption-desorption kinetics in nanoscopically confined oligomer films under shear

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