Showing papers on "Surface tension published in 2004"

Laminar drag reduction in microchannels using ultrahydrophobic surfaces

Abstract: A series of experiments is presented which demonstrate significant drag reduction for the laminar flow of water through microchannels using hydrophobic surfaces with well-defined micron-sized surface roughness. These ultrahydrophobic surfaces are fabricated from silicon wafers using photolithography and are designed to incorporate precise patterns of microposts and microridges which are made hydrophobic through a chemical reaction with an organosilane. An experimental flow cell is used to measure the pressure drop as a function of the flow rate for a series of microchannel geometries and ultrahydrophobic surface designs. Pressure drop reductions up to 40% and apparent slip lengths larger than 20 μm are obtained using ultrahydrophobic surfaces. No drag reduction is observed for smooth hydrophobic surfaces. A confocal surface metrology system was used to measure the deflection of an air–water interface that is formed between microposts and supported by surface tension. This shear-free interface reduces the ...

Maximal deformation of an impacting drop

Abstract: We first study the impact of a liquid drop of low viscosity on a super-hydrophobic surface. Denoting the drop size and speed as are the liquid density and surface tension). This law is also observed to hold on partially wettable surfaces, provided that liquids of low viscosity (such as water) are used. The law is interpreted as resulting from the effective acceleration experienced by the drop during its impact. Viscous drops are also analysed, allowing us to propose a criterion for predicting if the spreading is limited by capillarity, or by viscosity.

Surface tension effect on the mechanical properties of nanomaterials measured by atomic force microscopy

Abstract: The effect of reduced size on the elastic properties measured on silver and lead nanowires and on polypyrrole nanotubes with an outer diameter ranging between 30 and 250 nm is presented and discussed. Resonant-contact atomic force microscopy (AFM) is used to measure their apparent elastic modulus. The measured modulus of the nanomaterials with smaller diameters is significantly higher than that of the larger ones. The latter is comparable to the macroscopic modulus of the materials. The increase of the apparent elastic modulus for the smaller diameters is attributed to surface tension effects. The surface tension of the probed material may be experimentally determined from these AFM measurements.

Adhesively-bonded joints and repairs in metallic alloys, polymers and composite materials: Adhesives, adhesion theories and surface pretreatment

Abstract: In the present paper, the following topics are reviewed in detail: (a) the available adhesives, as well as their recent advances, (b) thermodynamic factors affecting the surface pretreatments including adhesion theories, wettability, surface energy, (c) bonding mechanisms in the adhesive joints, (d) surface pretreatment methods for the adhesively bonded joints, and as well as their recent advances, and (e) combined effects of surface pretreatments and environmental conditions on the joint durability and performance. Surface pretreatment is, perhaps, the most important process step governing the quality of an adhesively bonded joint. An adhesive is defined as a polymeric substance with viscoelastic behavior, capable of holding adherends together by surface attachment to produce a joint with a high shear strength. Adhesive bonding is the most suitable method of joining both for metallic and non-metallic structures where strength, stiffness and fatigue life must be maximized at a minimum weight. Polymeric adhesives may be used to join a large variety of materials combinations including metal-metal, metal-plastic, metal-composite, composite-composite, plastic-plastic, metal-ceramic systems. Wetting and adhesion are also studied in some detail in the present paper since the successful surface pretreatments of the adherends for the short- and long-term durability and performance of the adhesive joints mostly depend on these factors. Wetting of the adherends by the adhesive is critical to the formation of secondary bonds in the adsorption theory. It has been theoretically verified that for complete wetting (i.e., for a contact angle θ equal to zero), the surface energy of the adhesive must be lower than the surface energy of the adherend. Therefore, the primary objective of a surface pretreatment is to increase the surface energy of the adherend as much as possible. The influence of surface pretreatment and aging conditions on the short- and long-term strength of adhesive bonds should be taken into account for durability design. Some form of substrate pretreatment is always necessary to achieve a satisfactory level of long-term bond strength. In order to improve the performance of adhesive bonds, the adherends surfaces (i.e., metallic or non-metallic) are generally pretretead using the (a) physical, (b) mechanical, (c) chemical, (d) photochemical, (e) thermal, or (e) plasma method. Almost all pretreatment methods do bring some degree of change in surface roughness but mechanical surface pretreatment such as grit-blasting is usually considered as one of the most effective methods to control the desired level of surface roughness and joint strength. Moreover, the overall effect of mechanical surface treatment is not limited to the removal of contamination or to an increase in surface area. This also relates to changes in the surface chemistry of adherends and to inherent drawbacks of surface roughness, such as void formations and reduced wetting. Suitable surface pretreatment increases the bond strength by altering the substrate surface in a number of ways including (a) increasing surface tension by producing a surface free from contaminants (i.e., surface contamination may cause insufficient wetting by the adhesive in the liquid state for the creating of a durable bond) or removal of the weak cohesion layer or of the pollution present at the surface, (b) increasing surface roughness on changing surface chemistry and producing of a macro/microscopically rough surface, (c) production of a fresh stable oxide layer, and (d) introducing suitable chemical composition of the oxide, and (e) introduction of new or an increased number of chemical functions. All these parameters can contribute to an improvement of the wettability and/or of the adhesive properties of the surface.

The charge effect of cationic surfactants on the elimination of fibre beads in the electrospinning of polystyrene

Abstract: Polystyrene nanofibres were electrospun with the inclusion of cationic surfactants, dodecyltrimethylammonium bromide (DTAB) or tetrabutylammonium chloride (TBAC), in the polymer solution. A small amount of cationic surfactant effectively stopped the formation of beaded fibres during the electrospinning. The cationic surfactants were also found to improve the solution conductivity, but had no effect on the viscosity. Only DTAB had an effect on the surface tension of the polymer solution, the surface tension decreasing slightly with an increase in the concentration of DTAB. The formation of beaded fibres was attributed to an insufficient stretch of the filaments during the whipping of the jet, due to a low charge density. Adding the cationic surfactants improved the net charge density that enhanced the whipping instability. The jet was stretched under stronger charge repulsion and at a higher speed, resulting in an exhaustion of the bead structure. In addition, a polymer/surfactant interaction was found in the polystyrene–DTAB solution system, while this interaction was not found in the polystyrene–TBAC system. The polymer/surfactant interaction led to the formation of thinner fibres than those formed in the absence of the interaction. The effects of a non-ionic surfactant, Triton X-405, on the electrospun fibres were also studied. The addition of Triton X-405 did not eliminate the fibre beads, but reduced the bead numbers and changed the morphology. Triton X-405 slightly improved the solution conductivity, and had a minor effect on the surface tension, but no effect on the viscosity.

Spreading of nanofluids driven by the structural disjoining pressure gradient.

Abstract: This paper discusses the role of the structural disjoining pressure exerted by nanoparticles on the spreading of a liquid film containing these particles. The origin of the structural disjoining pressure in a confined geometry is due to the layering of the particles normal to the confining plane and has already been traced to the net increase in the entropy of the system in previous studies. In a recent paper, Wasan and Nikolov (Nature, 423 (2003) 156) pointed out that the structural component of the disjoining pressure is strong enough to move a liquid wedge; this casts a new light on many applications-most notably, detergency. While the concept of spreading driven by the disjoining pressure is not new, the importance of the structural disjoining pressure arises from its long-range nature (as compared to the van der Waals' force), making it an important component of the overall force balance near the contact line. In this paper, we report on a parametric study of the spreading phenomena by examining the effects of nanoparticle size, concentration and polydispersity on the displacement of an oil-aqueous interface with the aqueous bulk containing nanoparticles. The solution of the extended Laplace-Young equations for the profile of the meniscus yields the position of the nominal contact line under the action of the structural disjoining pressure. Simulations show that the displacement of the contact line is greater with a high nanoparticle volume fraction, small particles for the same volume fraction, monodispersed (in size) particles rather than polydispersed particles and when the resisting capillary pressure is small, i.e., when the interfacial tension is low and/or the radius of the dispersed phase drop/bubble is large.

A model for the phase stability of arbitrary nanoparticles as a function of size and shape

Abstract: A thermodynamic model describing relative stability of different shapes for nanoparticles as a function of their size was developed for arbitrary crystalline solids and applied to group IV semiconductors. The model makes use of various surface, edge and corner energies, and takes into account surface tension. Approximations and importance of each term of the model were analyzed. The predictions for clean and hydrogenated diamond nanoparticles are compared to explicitly calculated density functional results. It is shown that diamond nanocrystal morphology is markedly different from silicon and germanium.

Scaling law in liquid drop coalescence driven by surface tension

Abstract: This Letter reports experimental results on the coalescence of two liquid drops driven by surface tension. Using a high speed imaging system, we studied the early-time evolution of the liquid bridge that is formed upon the initial contact of two liquid drops in air. Experimental results confirmed the scaling law that was proposed by Eggers et al. based on a simple and yet elegant physical argument. We found that the liquid bridge radius rb follows the scaling law rb∝t1/2 in the inertial regime. Further experiments demonstrate that such scaling law is robust when using fluids of different viscosities and surface tensions. The prefactor of the scaling law, rb/t1/2, is shown to be ∝R1/4, where R is the inverse of the drop curvature at the point of contact. The dimensionless prefactor is measured to be in the range of 1.03–1.29, which is lower than 1.62, a prefactor predicted by the numerical simulation of Duchemin et al. for inviscid drop coalescence.

Elastic deformation of a fluid membrane upon colloid binding.

Abstract: When a colloidal particle adheres to a fluid membrane, it induces elastic deformations in the membrane which oppose its own binding. The structural and energetic aspects of this balance are investigated within the framework of a Helfrich Hamiltonian. Based on the full nonlinear shape equations for the membrane profile, a line of continuous binding transitions and a second line of discontinuous envelopment transitions are found, which meet at an unusual triple point. The regime of low tension is studied analytically using a small gradient expansion, while in the limit of large tension scaling arguments are derived which quantify the asymptotic behavior of phase boundary, degree of wrapping, and energy barrier. The maturation of animal viruses by budding is discussed as a biological example of such colloid-membrane interaction events.

Test of the Epstein-Plesset model for gas microparticle dissolution in aqueous media: effect of surface tension and gas undersaturation in solution.

Abstract: The gas from a free air bubble will readily dissolve in water, driven by two main factors: the concentration (undersaturation) of dissolved gas in the aqueous solution and the surface tension of the gas bubble−water interface via a Laplace overpressure in the bubble that this creates. This paper experimentally and theoretically investigates each of these effects individually. To study the effects of surface tension, single- and double-chain surfactants were utilized to control and define interfacial conditions of the microbubble in saturated solution. To study the effect of undersaturation, solid distearoylphosphocholine lipid was utilized to coat the gas microparticle with, essentially, a wax monolayer and to achieve zero tension in the surface. The experimental work was performed using a micromanipulation technique that allows one to create and micromanipulate single air microparticles (5−50 μm radius range) in infinite dilution and to accurately record the size of the particle as it loses volume due t...

Maximal deformation of an impacting drop

Abstract: are the liquid density and surface tension).This law is also observed to hold on partially wettable surfaces, provided that liquidsof low viscosity (such as water) are used. The law is interpreted as resulting fromthe effective acceleration experienced by the drop during its impact. Viscous dropsare also analysed, allowing us to propose a criterion for predicting if the spreading islimited by capillarity, or by viscosity.

Molecular Dynamics Study of a Surfactant-Mediated Decane-Water Interface: Effect of Molecular Architecture of Alkyl Benzene Sulfonate

Abstract: The effect of molecular architecture of a surfactant, particularly the attachment position of benzene sulfonate on the hexadecane backbone, at the decane−water interface was investigated using atomistic MD simulations. We consider a series of surfactant isomers in the family of alkyl benzene sulfonates, denoted by m-C16, indicating a benzene sulfonate group attached to the mth carbon in a hexadecane backbone. The equilibrated model systems showed a well-defined interface between the decane and water phases. We find that surfactant 4-C16 has a more compact packing, in terms of the interfacial area and molecular alignment at the interface, than other surfactants simulated in this study. Furthermore, surfactant 4-C16 leads to the most stable interface by having the lowest interface formation energy. The interfacial thickness is the largest in the case of surfactant 4-C16, with the thickness decreasing when the benzene sulfonate is located farther from the attachment position of 4-C16 (the 4th carbon). The interfacial tension profile was calculated along the direction perpendicular to the interface using the Kirkwood−Buff theory. From the comparison of the interfacial tension obtained from the interfacial tension profile, we found that surfactant 4-C16 induces the lowest interfacial tension and that the interfacial tension increases with decreasing interfacial thickness as a function of the attachment position of benzene sulfonate. Such a relationship between the interfacial thickness and interfacial tension is rationalized in terms of the miscibility of the alkyl tail of surfactant m-C16 with decane by comparing the “effective” length of the alkyl tail with the average end-to-end length of decane. Among the surfactants, the effective length of the 4-C16 alkyl tail (9.53 ± 1.36 A) was found to be closest to that of decane (9.97 ± 1.03 A), which is consistent with the results from the density profile and the interfacial tension profile.

The role of surfactants in Köhler theory reconsidered.

Abstract: . Atmospheric aerosol particles typically consist of inorganic salts and organic material. The inorganic compounds as well as their hygroscopic properties are well defined, but the effect of organic compounds on cloud droplet activation is still poorly characterized. The focus of the present study is the organic compounds that are surface active i.e. tend to concentrate on droplet surface and decrease the surface tension. Gibbsian surface thermodynamics was used to find out how partitioning between droplet surface and the bulk of the droplet affects the surface tension and the surfactant bulk concentration in droplets large enough to act as cloud condensation nuclei. Sodium dodecyl sulfate (SDS) was used together with sodium chloride to investigate the effect of surfactant partitioning on the Raoult effect (solute effect). While accounting for the surface to bulk partitioning is known to lead to lowered bulk surfactant concentration and thereby to increased surface tension compared to a case in which the partitioning is neglected, the present results show that the partitioning also alters the Raoult effect, and that the change is large enough to further increase the critical supersaturation and hence decrease cloud droplet activation. The fraction of surfactant partitioned to droplet surface increases with decreasing droplet size, which suggests that surfactants might enhance the activation of larger particles relatively more thus leading to less dense clouds. Cis-pinonic acid-ammonium sulfate aqueous solutions were studied in order to study the partitioning with compounds found in the atmosphere and to find out the combined effects of dissolution and partitioning behavior. The results show that the partitioning consideration presented in this paper alters the shape of the Kohler curve when compared to calculations in which the partitioning is neglected either completely or in the Raoult effect. In addition, critical supersaturation was measured for SDS particles with dry radii of 25-60nm using a static parallel plate Cloud Condensation Nucleus Counter. The experimentally determined critical supersaturations agree very well with theoretical calculations taking the surface to bulk partitioning fully into account and are much higher than those calculated neglecting the partitioning.

Transient and steady shapes of droplets attached to a surface in a strong electric field

Abstract: The shape evolution of small droplets attached to a conducting surface and subjected to relatively strong electric fields is studied both experimentally and numerically. The problem is motivated by the phenomena characteristic of the electrospinning of nanofibres. Three different scenarios of droplet shape evolution are distinguished, based on numerical solution of the Stokes equations for perfectly conducting droplets. (i) In sufficiently weak (subcritical) electric fields the droplets are stretched by the electric Maxwell stresses and acquire steady-state shapes where equilibrium is achieved by means of the surface tension. (ii) In stronger (supercritical) electric fields the Maxwell stresses overcome the surface tension, and jetting is initiated from the droplet tip if the static (initial) contact angle of the droplet with the conducting electrode is a, < 0.8π; in this case the jet base acquires a quasi-steady, nearly conical shape with vertical semi-angle β ≤ 30°, which is significantly smaller than that of the Taylor cone (β T = 49.3°). (iii) In supercritical electric fields acting on droplets with contact angle in the range 0.8π < α s < π there is no jetting and almost the whole droplet jumps off, similar to the gravity or drop-on-demand dripping. The droplet-jet transitional region and the jet region proper are studied in detail for the second case, using the quasi-one-dimensional equations with inertial effects and such additional features as the dielectric properties of the liquid (leaky dielectrics) taken into account. The flow in the transitional and jet region is matched to that in the droplet. By this means, the current-voltage characteristic I = I(U) and the volumetric flow rate Q in electrospun viscous jets are predicted, given the potential difference applied. The predicted dependence I = I(U) is nonlinear due to the convective mechanism of charge redistribution superimposed on the conductive (ohmic) one. For U = O(10kV) and fluid conductivity σ = 10 -4 Sm -1 , realistic current values 1=O(10 2 nA) were predicted.

The solid surface free energy calculation. I. In defense of the multicomponent approach.

Abstract: The acid-base approach to the calculation of solid surface free energy and liquid-liquid interfacial tensions is a practical example of application of correlation analysis, and thus it is an approximate approach. In these limits, and provided that wide and well-obtained sets of contact angles or interfacial tension data are used for their computation, surface tension components can be considered as material properties. Although their numerical value depends on the characteristics of the chosen reference material, their chemical meaning is independent on the selected scale. Contact angles contain accessible information about intermolecular forces; using surface tension component (STC) acid-base theory, one can extract this information only making very careful use of the mathematical apparatus of correlation analysis. The specific mathematical methods used to obtain these results are illustrated by using as an example a base of data obtained by the supporters of the equation-of-state theory (EQS). The achievements are appreciably good and the agreement between STC and EQS is discussed.

Size tailoring of oxide nanoparticles by precipitation in aqueous medium. A semi-quantitative modelling

Abstract: Chemistry in aqueous solution is an easy and versatile method to form nanosized metal oxide particles. Considering our previous results on magnetite Fe3O4, anatase TiO2, brucite Mg(OH)2, and boehmite γ-AlOOH, we show that the strict control of the physicochemical conditions of the precipitation, essentially the acidity and ionic strength in the absence of complexing species, enables the tailoring of the particle size in the range 2–15 nm and, in some cases, of their morphology. We show that the variations in size and/or shape are tightly related to the variation of the electrostatic surface charge density of the particles, which induces a variation of the oxide-solution interfacial tension, and, consequently, a decrease of the surface energy. Such an effect enables the control of the surface area of the system. A semi-quantitative model is presented, which accounts for the effects observed for particles isotropic or anisotropic in shape.

A negative surface energy for alumina

Abstract: The surface energy of a solid measures the energy cost of increasing the surface area. All normal solids therefore have a positive surface energy-if it had been negative, the solid would disintegrate. For this reason it is also generally believed that when certain ceramics can be found in a highly porous form, this is a metastable state, which will eventually sinter into the bulk solid at high temperatures. We present theoretical evidence suggesting that for theta-alumina, the surface energy is strongly dependent on the size of the crystallites, and that for some facets it is negative for thicknesses larger than approximately 1 nm. This suggests a completely new picture of porous alumina in which the high-surface-area, nanocrystalline form is the thermodynamic ground state. The negative surface energy is found to be related to a particularly strongly adsorbed state of dissociated water on some alumina surfaces. We also present new experimental evidence based on infrared spectroscopy, in conjunction with X-ray diffraction and surface-area measurements, that theta-alumina has indeed very stable surface OH groups at high temperatures, and that this form of alumina does not sinter even at temperatures up to 1,300 K.

Applied colloid and surface chemistry

Abstract: Preface. 1 Introduction. Introduction to the nature of colloidal solutions. The forces involved in colloidal stability. Types of colloidal systems. The link between colloids and surfaces. Wetting properties and their industrial importance. Recommended resource books. Appendices. 2 Surface Tension and Wetting. The equivalence of the force and energy description of surface tension and surface energy. Derivation of the Laplace pressure equation. Methods for determining the surface tension of liquids. Capillary rise and the free energy analysis. The Kelvin equation. The surface energy and cohesion of solids. The contact angle. Industrial Report: Photographic--quality printing. Sample problems. Experiment 2.1: Rod in free surface (RIFS) method for the measurement of the surface tension of liquids. Experiment 2.2: Contact angle measurements. 3 Thermodynamics of Adsorption. Basic surface thermodynamics. Derivation of the Gibbs adsorption isotherm. Determination of surfactant adsorption densities. Industrial Report: Soil microstructure, permeability and interparticle forces. Sample problems. Experiment 3.1: Adsorption of acetic acid on to activated charcoal. 4 Surfactants and Self--assembly. Introduction to surfactants. Common properties of surfactant solutions. Thermodynamics of surfactant self--assembly. Self--assembled surfactant structures. Surfactants and detergency. Industrial Report: Colloid science in detergency. Sample problems. Experiment 4.1: Determination of micelle ionization. 5 Emulsions and Microemulsions. The conditions required to form emulsions and microemulsions. Emulsion polymerization and the production of latex paints. Photographic emulsions. Emulsions in food science. Industrial Report: Colloid science in foods. Experiment 5.1: Determination of the phase behaviour of microemulsions. Experiment 5.2: Determination of the phase behaviour of concentrated surfactant solutions. 6 Charged Colloids. The formation of charged colloids in water. The theory of the diffuse electrical double--layer. The Debye length. The surface charge density. The zeta potential. The Huckel equation. The Smoluchowski equation. Corrections to the Smoluchowski equation. The zeta potential and flocculation. The interaction between double--layers. The Derjaguin approximation. Industrial Report: The use of emulsions in coatings. Sample problems. Experiment 6.1: Zeta potential measurements at the silica/water interface. 7 Van der Waals forces and Colloid Stability. Historical development of van der Waals forces and the Lennard--Jones potential. Dispersion forces. Retarded forces. Van der Waals forces between macroscopic bodies. Theory of the Hamaker constant. Use of Hamaker constants. The DLVO theory of colloid stability. Flocculation. Some notes on van der Waals forces. Industrial Report: Surface chemistry in water treatment. Sample problems. 8 Bubble Coalescence, Foams and Thin Surfactant Films. Thin--liquid--film stability and the effects of surfactants. Thin--film elasticity. Repulsive forces in thin liquid films. Froth flotation. The Langmuir trough. Langmuir--Blodgett films. Experiment 8.1: Flotation of powdered silica. Appendices. 1 Useful Information. 2 Mathematical Notes on the Poisson--Boltzmann Equation. 3 Notes on Three--dimensional Differential Calculus and the Fundamental Equations of Electrostatics.

Wettability interpretation of oxygen plasma modified poly(methyl methacrylate).

Abstract: Poly(methyl methacrylate) (PMMA) has been modified via a dc pulsed oxygen plasma for different treatment times. The modified surfaces were characterized by X-ray photoelectron spectroscopy (XPS), optical profilometer, zeta potential, and advancing contact angle measurements. The measured advancing contact angles of water decreased considerably as a function of discharge. Several oxygen-based functionalities (carbonyl, carboxyl, carbonate, etc.) were detected by XPS, while zeta potential measurements confirmed an increase in negative charge for the treated PMMA surface. Evaluating the correlation between the concentration of polar chemical species and zeta potential, we found that increase in surface hydrophilicity results from the coeffect due to incorporation of oxygen functional groups and creation of charge states. The electrical double layer (EDL) effect was also considered in contact angle interpretation by introducing an additional surface tension term into Young's equation. We also found that EDL c...

Mixed Solutions of Anionic and Zwitterionic Surfactant (Betaine): Surface-Tension Isotherms, Adsorption, and Relaxation Kinetics

Abstract: Here, we present experimental surface-tension isotherms of mixed solutions of two surfactants, sodium dodecyl sulfate (SDS) and cocoamidopropyl betaine (Betaine), measured by means of the Wilhelmy plate method. The kinetics of surface-tension relaxation exhibits two characteristic time scales, which have been distinguished to determine correctly the equilibrium surface tension. The transition from the zwitterionic to the cationic form of Betaine is detected by surface-tension measurements. Synergistic dependence of the critical micellization concentration on the composition of the surfactant blend is established. The experimental surface-tension isotherms are fitted by means of the two-component van der Waals model, and an excellent agreement between theory and experiment was achieved. Having determined the parameters of the model, we calculated different properties of the mixed surfactant adsorption layer at various concentrations of SDS, Betaine, and salt. Such properties are the adsorptions of the two ...

Adsorption of oppositely charged polyelectrolyte/surfactant complexes at the air/water interface: formation of interfacial gels.

Abstract: The adsorption and complexation of polystyrene sulfonate (a highly charged anionic polyelectrolyte) and dodecyltrimethylammonium bromide (a cationic surfactant) at the air-water interface can lead to interfacial gels that strongly influence foam-film drainage and stability. The formation and characteristics of these gels have been studied by combining surface tension, ellipsometry, and foam-film drainage experiments. Simultaneously, the solution electromotive force is measured and used to track the polymer-surfactant interactions in the bulk solution. We find that surface gelation occurs above the critical aggregation concentration in solution but before bulk precipitation of the polymer-surfactant complexes. Furthermore, we reveal that strong readsorption of polymer-surfactant complexes occurs during the resolubilization of the precipitated complexes at high surfactant concentrations (i.e., >>critical micelle concentration). Seemingly overlooked in the past, this readsorption significantly influences the surface rheological properties and foam-film drainage of these systems.