Computer Simulation of the Surface Free Energy of the Si(100) Surface and the Line Free Energies Associated with Steps on This Surface†

2004 ◽  
Vol 108 (51) ◽  
pp. 19721-19728 ◽  
Author(s):  
Sweta Somasi ◽  
Bamin Khomami ◽  
Ronald Lovett
Keyword(s):  
Computer Simulation ◽  
Free Energy ◽  
Surface Free Energy ◽  
Free Energies

Molecular orientation of liquid aliphatic hydrocarbons on the surface and at the interface with water

1989 ◽  
Vol 54 (12) ◽  
pp. 3171-3186 ◽  
Author(s):  
Jan Kloubek
Keyword(s):  
Free Energy ◽  
Surface Free Energy ◽  
Molecular Orientation ◽  
Phase Changes ◽  
Aliphatic Hydrocarbons ◽  
Water Molecules ◽  
Free Energies ◽  
Dispersion Component ◽  
System Water ◽  
Orientation Of Molecules

The validity of the Fowkes theory for the interaction of dispersion forces at interfaces was inspected for the system water-aliphatic hydrocarbons with 5 to 16 C atoms. The obtained results lead to the conclusion that the hydrocarbon molecules cannot lie in a parallel position or be randomly arranged on the surface but that orientation of molecules increases there the ration of CH3 to CH2 groups with respect to that in the bulk. This ratio is changed at the interface with water so that the surface free energy of the hydrocarbon, γH, rises to a higher value, γ’H, which is effective in the interaction with water molecules. Not only the orientation of molecules depends on the adjoining phase and on the temperature but also the density of hydrocarbons on the surface of the liquid phase changes. It is lower than in the bulk and at the interface with water. Moreover, the volume occupied by the CH3 group increases on the surface more than that of the CH2 group. The dispersion component of the surface free energy of water, γdW = 19.09 mJ/m2, the non-dispersion component, γnW = 53.66 mJ/m2, and the surface free energies of the CH2 and CH3 groups, γ(CH2) = 32.94 mJ/m2 and γ(CH3) = 15.87 mJ/m2, were determined at 20 °C. The dependence of these values on the temperature in the range 15-40 °C was also evaluated.

Solid surface free energy analysis using inkjet droplets

2011 ◽  
Vol 1360 ◽  
Author(s):  
Kazuhiro Fukada ◽  
Hayato Sakai ◽  
Taku Hasobe ◽  
Takashi Masuda ◽  
Tatsuya Shimoda
Keyword(s):  
Electron Microscopy ◽  
Free Energy ◽  
Surface Free Energy ◽  
Energy Analysis ◽  
Free Energies ◽  
Organic Solution ◽  
Transmission Electron ◽  
Free Energy Analysis ◽  
The Relationship ◽  
Tem Grid

ABSTRACTWe measured the surface free energy of a substrate by transmission electron microscopy (TEM) using sub-millimetre-sized inkjet droplets. By employing two types of TEM grids with different surface free energies, we investigated the relationship between the surface energy and the patterns of an organic solution dried on the grids. We confirmed that the generation of the porphyrin hexamer [(H2PAC15)6TPh] patterns was affected by the surface free energy of the TEM grid.

Interactions of components and elements of the surface free energy at interfaces

1991 ◽  
Vol 56 (2) ◽  
pp. 277-295 ◽  
Author(s):  
Jan Kloubek
Keyword(s):  
Free Energy ◽  
Surface Free Energy ◽  
Polar Phase ◽  
Free Energies ◽  
Dispersion Component ◽  
Liquid Systems ◽  
Interfacial Free Energies ◽  
Total Surface Free Energy ◽  
Solid Liquid ◽  
New Hypothesis

A new hypothesis is suggested for the evaluation of the components (γd and γab) and the elements (γa and γb) of the surface free energy. The respective equations are introduced for the interactions at interfaces between a non-polar acid and non-polar base, a polar phase and non-polar acid or base, and two polar phases. The dispersion component, γd, equals the total surface free energy of non-polar phases. However, they can interact at the interface as an acid or a base through their single permanent elements γa or γb, respectively. Otherwise, induced elements γia and γib can also be effective. The surface free energy of polar phases is additively composed of the dispersion, γd, and acid-base components, γab = 2(γaγb)1/2. The proposed equation are verified using the known values of the surface and interfacial free energies for the liquid-liquid systems and they are applied to the solid-liquid interfaces. The values of the elements are determined for water, γwa = 67.7 and γwb = 10.6 mJ/m2, and for other liquids, such as glycerol, formamide, mercury, benzene, diethyl ether and trichloromethane.

Investigation of some phenomena occurring during continuous ink-jet printing of ceramics

2001 ◽  
Vol 16 (2) ◽  
pp. 373-384 ◽  
Author(s):  
B. Y. Tay ◽  
M. J. Edirisinghe
Keyword(s):  
Surface Tension ◽  
Free Energy ◽  
Surface Free Energy ◽  
Modulation Frequency ◽  
Free Energies ◽  
Ink Jet Printing ◽  
Ink Jet ◽  
Jet Printing ◽  
Vertical Walls ◽  
Total Surface Free Energy

A ceramic ink was prepared, characterised, and subjected to continuous ink-jet printing. The optimum modulation frequency for printing was estimated. The surface free energies of several substrates were determined and different patterns of the ink droplets were printed on these. Phenomena occurring during the process were investigated. The drop-by-drop resolution and ink spreading were found to be dependent on the dispersive/total surface free energy ratio of the substrates. Ink drying was accompanied by powder migration in the droplets deposited on substrates with a surface free energy lower than the surface tension of the ink. Printing of multiple layers was accompanied by the appearance of ridges, splattering, and non-vertical walls. The causes of these phenomena are discussed in this paper.

Surface free energy of a soil clay fraction in relation to aggregate stability

Clay Minerals ◽  
1993 ◽  
Vol 28 (1) ◽  
pp. 145-148
Author(s):  
B. Jańczuk ◽  
G. Józefaciuk ◽  
M. Hajnos ◽  
T. Bialopiotrowicz ◽  
A. Kliszcz
Keyword(s):  
Contact Angle ◽  
Free Energy ◽  
Surface Free Energy ◽  
Clay Fraction ◽  
Aggregate Stability ◽  
Soil Aggregate ◽  
Free Energies ◽  
Soil Aggregate Stability ◽  
Soil Clay ◽  
Energy Components

When studying surface free energies of clays in relation to clay composition, we calculated that in some instances the aggregate stability should be higher for Na- then for Ca-forms. This raised the question as to whether the results obtained with the surface free energy approach are reliable for estimation of soil aggregate stability. The aim of the present work was to measure the surface free energy components and attractive forces for a clay calculated from measurements of the contact angle of glycerol, diiodomethane and cis-decalin and to compare them with results of penetrometrical measurements.

Formation of Surface Structure in Vulcanizates and Surface Structure Changes in Air

1995 ◽  
Vol 68 (1) ◽  
pp. 97-109 ◽  
Author(s):  
Kunio Mori ◽  
Kentaro Kanae ◽  
Hidetoshi Hirahara ◽  
Yoshiyuki Oishi
Keyword(s):  
Free Energy ◽  
Surface Structure ◽  
Surface Free Energy ◽  
High Surface ◽  
Surface Region ◽  
Interfacial Free Energy ◽  
Chemical Compositions ◽  
Free Energies ◽  
Dry Air ◽  
Structure Changes

Abstract The formation theory of surface structure during vulcanization was developed on the basis of an interfacial concept. The theory showed the chemical compositions of polar and nonpolar components on the vulcanizate surface to be determined as an excess interfacial free energy between rubber compounds and molds decreases. The surface free energies of molds reflected clearly the corresponding surface free energy of vulcanizates prepared from copolymers and polar polymers. Nonpolar polymers were not influenced by the surface free energies of molds. The surface free energies of vulcanizates decreased slightly with the concentration of network chains owing to the entropy of rubber segments. The surface free energies of molds affected the chemical compositions at the topmost surface region to the upper surface region on vulcanizates. NBR vulcanizates with high surface free energy increased the contact angle of water after standing in dry air. In the dry air environment, topmost surface layer nitrile groups were buried in the bulk of NBR vulcanizates and butadiene units subsequently overturn to the topmost, layer. In this case, the vulcanizate surface chemical composition was influenced only at the topmost surface region. ESCA spectra N1s peak intensities on NBR vulcanizates was consistent with these observation.

Interaction at interfaces and induction of surface free energy components

1987 ◽  
Vol 52 (2) ◽  
pp. 271-286 ◽  
Author(s):  
Jan Kloubek
Keyword(s):  
Free Energy ◽  
Surface Free Energy ◽  
Organic Liquid ◽  
Interaction Mechanism ◽  
Work Of Adhesion ◽  
Polar Component ◽  
Published Data ◽  
Free Energies ◽  
Dispersion Component ◽  
Mechanism Of Interaction

A set of published data on surface free energy (γ1, γ2) and interfacial energy (γ12) for interfaces mercury-organic liquid, mercury-water, and water-organic liquid (125 pairs altogether) has been critically evaluated. It has been found that the Antonow rule does not hold, that the Neumann equation is suitable for determining the work of adhesion, if γ1 and γ2 are not too different, and that the Fowkes equation can be used to assess the type of interaction at the interface. A hypothesis has been suggested which states that, besides the interaction between dispersion components of the surface free energies of the adjoining phases and the interaction between the non-dispersion components of the same type in bulk, a non-dispersion component of one phase may interact by inducing a component of the same type in the other phase near the interface. Relations concerning the mechanism of interaction at the interface have been derived. Also, the relation between the Girifalco-Good, Neumann and complemented Fowkes equation has been evaluated. For the particular liquids the dispersion portion of their surface free energies and the interaction mechanism at their interface with water and mercury have been estimated. For water, e.g. the polar component of the surface free energy (14.7 mJ m-2) and the hydrogen-bond component (36.3 mJ m-2) have been determined. The introduction of the induced component of the surface free energy is shown, as an example, for water-aromatic hydrocarbons and water-alcohols systems.

Simulations of the Structure and Properties of the Polyethylene Crystal Surface

1995 ◽  
Vol 408 ◽  
Author(s):  
J. L. Wilhelmi ◽  
G. C. Rutledge
Keyword(s):  
Free Energy ◽  
Surface Free Energy ◽  
Crystal Surface ◽  
Excess Entropy ◽  
Free Energy Calculations ◽  
Intermolecular Potential ◽  
Free Energies ◽  
Free Energy Surface ◽  
Lattice Mode ◽  
Molecular Layers

AbstractThe structures and thermodynamic properties of the (100), (010), and (110) lateral surfaces of extended-chain polyethylene crystals between 0 K and 300 K were determined by free energy minimization using consistent quasi-harmonic lattice dynamics. Slight rotations of the outermost chains from their corresponding orientations in the bulk were observed. These deviations from bulk structure were confined to the first three molecular layers (approximately 10 Å) at the surface. Surface free energy calculations found the (110) surface to be the most stable over the entire temperature range modeled, with free energies ranging from 95.4 erg/cm2 to 103.5 erg/cm2, at temperatures of 0 K and 300 K, respectively. Surface free energies of the (100) and (010) surfaces were found to be at least 15% higher than the (110) surface, with the (100) surface slightly more stable than the (010) surface, over all temperatures considered. Surface free energy increases as the density of chains at the surface decreases. The surface free energy at low temperatures was determined predominantly by intermolecular potential energy; at higher temperatures, excess entropy accounted for nearly half the surface free energy. Surface entropy was almost entirely due to lattice mode motions.

scholarly journals Surface Testing of Dental Biomaterials—Determination of Contact Angle and Surface Free Energy

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2716
Author(s):  
Aneta Liber-Kneć ◽  
Sylwia Łagan
Keyword(s):  
Contact Angle ◽  
Free Energy ◽  
Surface Energy ◽  
Surface Free Energy ◽  
Sessile Drop ◽  
Dental Materials ◽  
Free Energy Calculations ◽  
Critical Surface ◽  
Free Energies ◽  
Acrylic Resins

The key goal of this study was to characterize surface properties of chosen dental materials on the base on the contact angle measurements and surface free energy calculations. Tested materials were incubated in the simulated oral environment and drinks to estimate an influence of conditions similar to those in the oral cavity on wetting and energetic state of the surface. Types of materials were as follows: denture acrylic resins, composite and PET-G dental retainer to compare basic materials used in a prosthetics, restorative dentistry and orthodontics. The sessile drop method was used to measure the contact angle with the use of several liquids. Values of the surface free energies were estimated based on the Owens–Wendt, van Oss–Chaudhury–Good and Zisman’s methods. The research showed that surface wetting depends on the material composition and storage conditions. The most significance changes of CA were observed for acrylic resins (84.7° ± 3.8° to 65.5° ± 3.5°) and composites (58.8° ± 4.1° to 49.1° ± 5.7°) stored in orange juice, and for retainers (81.9° ± 1.8° to 99.6° ± 4.5°) incubated in the saline solution. An analysis of the critical surface energy showed that acrylic materials are in the zone of good adhesion (values above 40 mJ/m2), while BIS-GMA composites are in the zone of poor adhesion (values below 30 mJ/m2). Study of the surface energy of different dental materials may contribute to the development of the thermodynamic model of bacterial adhesion, based on the surface free energies, and accelerate the investigation of biomaterial interaction in the biological environment.

Smectic A-Smectic B interface : faceting and surface free energy measurement

1989 ◽  
Vol 50 (24) ◽  
pp. 3527-3534 ◽  
Author(s):  
P. Oswald ◽  
F. Melo ◽  
C. Germain
Keyword(s):  
Free Energy ◽  
Surface Free Energy ◽  
Energy Measurement ◽  
Smectic A
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