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.

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.

scholarly journals Influence of Low-Pressure RF Plasma Treatment on Aramid Yarns Properties

Molecules ◽  
2020 ◽  
Vol 25 (15) ◽  
pp. 3476
Author(s):  
Alicja Nejman ◽  
Irena Kamińska ◽  
Izabela Jasińska ◽  
Grzegorz Celichowski ◽  
Małgorzata Cieślak
Keyword(s):  
Weight Loss ◽  
Free Energy ◽  
Radio Frequency ◽  
Plasma Treatment ◽  
Surface Free Energy ◽  
Low Pressure ◽  
Rf Plasma ◽  
Polar Component ◽  
Specific Strength ◽  
Dispersion Component

The aim of the study was to modify the surface free energy (SFE) of meta- (mAr) and para-aramid (pAr) yarns by their activation in low-pressure air radio frequency (RF) (40 kHz) plasma and assessment of its impact on the properties of the yarns. After 10 and 90 min of activation, the SFE value increased, respectively, by 14% and 37% for mAr, and by 10% and 37% for pAr. The value of the polar component increased, respectively by 22% and 57% for mAr and 20% and 62% for pAr. The value of the dispersion component for mAr and pAr increased respectively by 9% and 25%. The weight loss decreased from 49% to 46% for mAr and 62% to 50% for pAr after 90 min of activation. After 90 min, the specific strength for mAr did not change and for pAr it decreased by 40%. For both yarns, the 10 min activation in plasma is sufficient to prepare their surface for planned nanomodification.

The Influence of Mechanical and Mechanochemical Activation of Hardwood Wood Waste on Biocomposite Properties

2019 ◽  
Vol 800 ◽  
pp. 200-204
Author(s):  
Jevgenijs Jaunslavietis ◽  
Galia Shulga ◽  
Jurijs Ozolins ◽  
Brigita Neiberte ◽  
Anrijs Verovkins ◽  
...  
Keyword(s):  
Free Energy ◽  
Surface Free Energy ◽  
Mechanochemical Activation ◽  
Moisture Sorption ◽  
Wood Waste ◽  
Work Of Adhesion ◽  
Polar Component ◽  
Aspen Wood ◽  
Wood Polymer ◽  
The Impact

As the demand for sustainable environment friendly materials increases, the biocomposites such as wood-polymer composite (WPC) have gained more attention in past years. Wood wastes and by-products like sawdust, chips, bark and wood residues as well as recycled polymers can serve as raw materials for production of WPC. However, there are still many issues obtaining WPCs, mainly a poor compatibility between a hydrophobic polymer matrix and a hydrophilic wood filler. In the present study, mechanical and mechanochemical activation of aspen wood waste were performed to increase their compatibility with recycled polypropylene matrix in the WPC, and the impact of both methods on the biocomposite properties were studied. It was found, that mechanochemical activation (MCA) of aspen wood particles leads to increased hydrophobicity of the obtained WPC compared to the WPC with mechanically activated (MA) particles. Work of adhesion with water was remarkably lower for the WPC modified by MCA which also correlates with moisture sorption results. Surface free energy of the WPC modified by MCA was lower compared to the WPC modified by MA, mostly due to decreased the polar component of surface free energy. The modulus of elasticity (MOE) were competitive for both the WPC formulations, however, MCA led to increased flexural strength of WPC compared to MA.

scholarly journals Evidence for intermolecular forces involved in ladybird beetle tarsal setae adhesion

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Naoe Hosoda ◽  
Mari Nakamoto ◽  
Tadatomo Suga ◽  
Stanislav N. Gorb
Keyword(s):  
Free Energy ◽  
Surface Free Energy ◽  
Adhesion Force ◽  
Intermolecular Forces ◽  
Adhesive Force ◽  
Work Of Adhesion ◽  
Polar Component ◽  
Adhesion Mechanism ◽  
Ladybird Beetle ◽  
Ladybird Beetles

AbstractWhy can beetles such as the ladybird beetle Coccinella septempunctata walk vertically or upside-down on a smooth glass plane? Intermolecular and/or capillary forces mediated by a secretion fluid on the hairy footpads have commonly been considered the predominant adhesion mechanism. However, the main contribution of physical phenomena to the resulting overall adhesive force has yet to be experimentally proved, because it is difficult to quantitatively analyse the pad secretion which directly affects the adhesion mechanism. We observed beetle secretion fluid by using inverted optical microscopy and cryo-scanning electron microscopy, which showed the fluid secretion layer and revealed that the contact fluid layer between the footpad and substrate was less than 10–20 nm thick, thus indicating the possibility of contribution of intermolecular forces. If intermolecular force is the main physical phenomenon of adhesion, the force will be proportional to the work of adhesion, which can be described by the sum of the square roots of dispersive and polar parts of surface free energy. We measured adhesion forces of ladybird beetle footpads to flat, smooth substrates with known surface free energies. The adhesive force was proportional to the square-root of the dispersive component of the substrate surface free energy and was not affected by the polar component. Therefore, intermolecular forces are the main adhesive component of the overall adhesion force of the ladybird beetle. The footpads adhere more strongly to surfaces with higher dispersive components, such as wax-covered plant leaves found in the natural habitat of ladybird beetles. Based on the present findings, we assume ladybird beetles have developed this improved performance as an adaptation to the variety of plant species in its habitat.

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.

scholarly journals Optical Properties and van der Waals - London Dispersion Interactions of Polystyrene Determined by Vacuum Ultraviolet Spectroscopy and Spectroscopic Ellipsometry

2007 ◽  
Vol 60 (4) ◽  
pp. 251 ◽  
Author(s):  
Roger H. French ◽  
Karen I. Winey ◽  
Min K. Yang ◽  
Weiming Qiu
Keyword(s):  
Free Energy ◽  
Optical Properties ◽  
Surface Free Energy ◽  
Vacuum Ultraviolet ◽  
Van Der Waals ◽  
Interband Transitions ◽  
Dispersion Interactions ◽  
Dispersion Component ◽  
London Dispersion ◽  
Hamaker Constants

The interband optical properties of polystyrene in the vacuum ultraviolet (VUV) region have been investigated using combined spectroscopic ellipsometry and VUV spectroscopy. Over the range 1.5–32 eV, the optical properties exhibit electronic transitions we assign to three groupings, E1, E2, and E3, corresponding to a hierarchy of interband transitions of aromatic (π → π*), non-bonding (n → π*, n → σ*), and saturated (σ → σ*) orbitals. In polystyrene there are strong features in the interband transitions arising from the side-chain π bonding of the aromatic ring consisting of a shoulder at 5.8 eV (E1′) and a peak at 6.3 eV (E1), and from the σ bonding of the C–C backbone at 12 eV (E3′) and 17.1 eV (E3). These E3 transitions have characteristic critical point line shapes associated with one-dimensionally delocalized electron states in the polymer backbone. A small shoulder at 9.9 eV (E2) is associated with excitations possibly from residual monomer or impurities. Knowledge of the valence electronic excitations of a material provides the necessary optical properties to calculate the van der Waals–London dispersion interactions using Lifshitz quantum electrodynamics theory and full spectral optical properties. Hamaker constants and the van der Waals–London dispersion component of the surface free energy for polystyrene were determined. These Lifshitz results were compared to the total surface free energy of polystyrene, polarity, and dispersive component of the surface free energy as determined from contact angle measurements with two liquids, and with literature values. The Lifshitz approach, using full spectral Hamaker constants, is a more direct determination of the van der Waals–London dispersion component of the surface free energy of polystyrene than other methods.

Hydrophilic-Hydrophobic Characteristics of Wood-Polymer Composites Filled with Modified Wood Particles

2018 ◽  
Vol 762 ◽  
pp. 176-181
Author(s):  
Jevgenijs Jaunslavietis ◽  
Galia Shulga ◽  
Jurijs Ozolins ◽  
Brigita Neiberte ◽  
Anrijs Verovkins ◽  
...  
Keyword(s):  
Free Energy ◽  
Polymer Composites ◽  
Surface Free Energy ◽  
Moisture Sorption ◽  
Contact Angles ◽  
Work Of Adhesion ◽  
Wood Polymer ◽  
Wood Particles ◽  
Wood Polymer Composites ◽  
Modified Wood

In this study, hydrophobic-hydrophilic characteristics, including contact angle and moisture sorption of a modified wood filler and the wood-polymer composites (WPC) containing it was investigated. The wood filler obtained from aspen sawdust was modified by mild acid hydrolysis and by ammoxidation. Contact angles of the wood particles and the WPC samples were measured with Kruss K100M using the Washburn and Wilhelmy methods, respectively. Work of adhesion was calculated using Young-Dupre equation. Surface free energy as well as its dispersive and polar parts were found using Owens-Wendt-Rabel-Kaelble approach. It was found that the hydrolysis and the ammoxidation led to decrease of the hemicelluloses content in the lignocellulosic matrix. Beside this, the ammoxidation favours the formation of amide bonds in the ammoxidised particles. These changes enhanced the contact angles, decreased the work of adhesion, and decreased surface free energy of the WPC samples filled with the modified particles in comparison with the WPC sample that contained the unmodified ones. The treatment of the wood particles decreased the wettability towards water, but increased it towards recycled polypropylene. This positively effects mechanical properties of the samples.

INFLUENCE OF SURFACE FREE ENERGY ON ADHESION OF CrN THIN FILM DEPOSITED BY AIP METHOD

2012 ◽  
Vol 06 ◽  
pp. 509-514 ◽  
Author(s):  
HIKARU NOUDA ◽  
HIROATSU ODA ◽  
DAISUKE YONEKURA ◽  
RI-ICHI MURAKAMI
Keyword(s):  
Thin Film ◽  
Free Energy ◽  
Surface Free Energy ◽  
High Speed ◽  
Gas Flow ◽  
Sessile Drop ◽  
Ion Bombardment ◽  
Polar Component ◽  
Scratch Testing ◽  
The Relationship

The purpose of this study is to examine the relationship between adhesion of CrN thin film and the surface free energy of substrate. CrN film was deposited on JIS SKH2 high speed tool steel by arc ion plating (AIP) method. The surface free energy of the substrate was measured with/without ion bombardment process using nitrogen and argon gas under various gas flow rate before CrN deposition. The surface free energy was measured by the sessile drop method using distilled water and methylene iodide. The adhesion was evaluated by scratch testing and the relationship between a critical load and the surface free energy in each ion bombardment condition was discussed. As a result, it was found that the adhesion increased with decreasing the surface free energy, in particular the polar component strongly affects the adhesion.

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.

Sign in / Sign up

Export Citation Format

Share Document