Surface Tensiometer Research Articles

DBS/Brij 35 혼합계면활성제의 미셀화에 미치는 n-부탄올 효과

순수 물 및 n-부탄올 수용액(0.1M, 0.2M, 0.3M)에서 음이온 계면활성제인 sodium dodecyl benzenesulfonate(DBS)와 비이온 계면활성제인 dodecyl polyoxyethylene(23) lauryl ether(Brij 35)의 혼합계면활성제의 임계미셀농도(CMC)와 반대이온의 결합상수값(B)을 DBS의 겉보기 몰분율(1)의 함수로서 전도도법과 표면장력계법으로 측정하였다. 이와 같이 측정한 CMC값에 비이상적 혼합미셀화모델을 적용함으로써 여러 가지 열역학적 함수값(Xi, i, Ci, aiM, 및 Hmix)들을 계산하고 분석하였다. 그리고 DBS/Brij 35 혼합계면활성제의 미셀화에 미치는 n-부탄올의 농도에 따른 열역학 함수값들의 변화를 측정하고 분석하였다. The critical micelle concentration (CMC) and the counterion binding constant (B) in a mixed micellar state of the sodium dodecylbenzenesulfonate (DBS) with the polyoxyethylene(23) lauryl ether (Brij 35) at 25oC in water and aqueous solutions of n-butanol (0.1M, 0.2M, and 0.3M) were determined as a function of a1 (the overall mole fraction of DBS) by the use of electric conductivity method and surface tensiometer method. Various thermodynamic parameters (Xi, i, Ci, aiM, , and Hmix) were calculated by means of the equations derived from the nonideal mixed micellar model. The effect of n-butanol on the micellization of the DBS/Brij 35 mixtures has been also studied by analyzing the measured and calculated thermodynamic parameters.

DBS/Brij 30 혼합계면활성제의 미셀화에 대한 열역학적 연구

The critical micelle concentrations (CMC) and the counter ion binding constants (B) in a micellar state of the mixed surfactant systems of sodium dodecylbenzenesulfonate (DBS) with polyoxyethylene(4) lauryl ether (Brij 30) in water were determined as a function of 1 (the overall mole fraction of DBS) by the use of electric conductivity method and surface tensiometer method from 288 K to 308 K. Various thermodynamic parameters (Smo, Hmo, and Gmo) for the micellization of DBS/Brij 30 mixtures were calculated and analyzed from the temperature dependence of CMC values. The measured values of Gomare all negative but the values of Smo are positive in the whole measured temperature region. On the other hand, the values of Hmo are positive or negative, depending on the measured temperature and 1.

Synthesis of photodegradable TiO 2/stearate complex and characterization of its Langmuir monolayer at the air/water interface

The water pollution from organic compound has became a serious global problem. The TiO 2 photocatalyst illuminated with UV light can decompose organic compound. Since the specific gravity of TiO 2 particles is larger than water, the photodecomposition of organic compound in the water was difficult. So we synthesized TiO 2/stearate complex for the efficient decomposition of organic compound for the efficient photodegradation of aggregated organic pollutants. The photodegradable TiO 2/stearate complex has been prepared with sodium stearate. This was identified with FT-IR, water contact angle, TGA and TEM images. This complex was studied as Langmuir monolayer at the air/water interface on the miscibility and photodegradability of organic crude oil which was exposed at the sea water with pressure–area isotherm, Brewster angle microscope (BAM) and surface tensiometer.

Maleic diamide polymerizable surfactants. Applications in emulsion polymerization

A series of new polymerizable non-ionic and ionic surfactants (surfmers) with amides groups on both sides of the C=C double bonds have been prepared upon reaction of maleic isoimide carrying a long alkyl chain (or a benzyl group) with a hydrophilic amine derivative. Their critical micellar concentration (CMC) was measured with a surface tensiometer. They have been engaged in batch emulsion polymerization of styrene, and semi-batch seeded copolymerization of styrene and butyl acrylate, giving stable latexes during the polymerization process, and upon extraction with ethanol, showing a high rate of incorporation at the particle surface. However these surfmers do not confer good steric stabilization properties, which may be expected from the use of non-ionic surfactants. To cite this article: I. Klimenkovs et al., C. R. Chimie 6 (2003).

Interfacial interaction in sisal/epoxy composites and its influence on impact performance

AbstractTo obtain comprehensive knowledge of the interfacial effect on the impact performance of sisal fiber reinforced epoxy composites, the fiber surface was modified in different ways prior to compounding. By using a surface tensiometer and dynamic mechanical analyzer, interfacial interactions in the composites were characterized. The results indicated that the chemical treatments brought about strong bonding between sisal bundles and the epoxy matrix. The subsequent impact tests revealed that the microfailure mechanism involved is a function of interfacial adhesion and fiber length continuity (i.e., continuous or discontinuous fiber). In the case of unidirectional laminates, an optimum fiber treatment should be able to result in an increased affinity between fiber bundles and matrix and a decreased intercellular adhesion. In this way, extension and uncoiling of the spirally arranged microfibrils, a main energy consumption process of plant fibers, can impart significant toughness to the composites. For short fiber composites, the interfacial strength should be properly tailored so as to increase energy dissipation through debonding and pullout of fiber bundles.

Surface-active properties of vasoactive intestinal peptide☆

The purpose of this study was to determine whether human vasoactive intestinal peptide (VIP) aggregates in aqueous solution and, if so, whether the peptide interacts with a biomimetic phospholipid monolayer and increases surface pressure. Using a custom-made Teflon trough containing HEPES buffer (pH 7.4) at room temperature and a surface tensiometer, we found that the critical micellar concentration (CMC) of VIP is 0.4 μM. Surface pressure of a dipalmitoylphosphatidylcholine (DPPC) monolayer spread over the HEPES buffer declined significantly over 120 min because of phospholipid decomposition. However, injection of VIP at concentrations above CMC into the subphase of the monolayer elicited a significant concentration-dependent increase in surface pressure that persisted for 120 min ( P < 0.05). Unlike VIP, injection of [ 8Arg]-vasopressin at an equimolar concentration only prevented the time-dependent decline in DPPC monolayer surface pressure. Taken together, these data indicate that human VIP aggregates in aqueous solution and expresses surface-active properties at physiological concentrations in vitro. We suggest that these attributes could have a role in modulating the bioactive effects of the peptide in vivo.

Mechanistic studies on surfactant-induced membrane permeability enhancement.

To gain some mechanistic understanding of surfactant-induced membrane permeabilization and identify a surfactant physical property that can be used as a predictor for intestinal membrane permeability enhancement. The maximum surface pressures (piCMC) of series of anionic and non-ionic surfactants as indicators of surface activity were determined using a bubble surface tensiometer, and related to in vivo intestinal membrane permeability and acute damage data of the same surfactants from a previous work. Phospholipid bilayers with constant surface pressures and monolayers with different surface pressures were used as model membranes to systematically study membrane permeability enhancement and membrane penetration of surfactants at different concentrations. Surfactants that did not permeabilize or acutely damage the intestinal wall generally exhibited a piCMC < 25 dyne/cm. Permeability enhancement and acute damage increased as piCMC increased beyond 25 dyne/cm. This critical threshold value at around 25 dynes/cm was also observed with in vitro experiments using phospholipid vesicles and monolayers. Data support the hypothesis that the threshold phenomenon originates from the interfacial tension at the membrane/water interface, which controls the surface adsorption process of surfactant molecules onto the membrane. For a surfactant to permeabilize and acutely damage the intestinal wall, it must exhibit a surface pressure of greater than 25 dynes/cm. This threshold value is related to an intrinsic property, surface pressure, of the phospholipid membranes. Since the surfactant surface pressure is a property of the surfactant monomer, partition of the surfactant monomer, not the micelle, into the membrane is an obligate step in membrane permeabilization. Above the surfactant critical micelle concentration, CMC, micelles may act as a depot to continuously replace aqueous surfactant monomers taken up by the membrane. For some surfactants above CMC, sufficient number of monomers can partition into the membrane to cause solubilization of membrane lipids in surfactant micelles.

Germ-Layer Surface Tensions and “Tissue Affinities” inRana pipiensGastrulae: Quantitative Measurements

The morphogenetic properties causing germ-layer spreading and stratification in amphibian gastrulation were called “tissue affinities” by Holtfreter. The differential adhesion hypothesis (DAH) attributes such liquidlike tissue rearrangements to forces generated by intercellular adhesions within and between the migrating cell populations. This theory predicts that, among the primary germ layers, the cohesiveness of deep ectoderm should be the greatest, that of deep mesoderm should be intermediate, and that of deep endoderm should be the least. Also, the cohesiveness of differentiating neural ectoderm should increase after induction, causing it to internalize and segregate from epidermis. The DAH also explains why the cohesiveness of “liquid” tissues, whose cells are free to rearrange, should be measurable as tissue surface tensions. Using a specially designed tissue surface tensiometer, we demonstrate that (i) aggregates ofRana pipiensdeep germ layers do possess liquid-like surface tensions, (ii) their surface tension values lie in precisely the sequence necessary to account for germ-layer stratificationin vitroandin vivo,and (iii) the surface tension of deep ectoderm just underlain by the archenteron roof is twice that of not-yet-underlain deep ectoderm. These measurements provide direct, quantitative evidence that the “tissue affinities” governing germ-layer flow during early stages of vertebrate morphogenesis are reflected in tissue surface tensions.

A tensiometer for measuring hydraulic potentials on surfaces of porous rock

A laboratory method for obtaining tensiometer measurements on surfaces of porous rock and soil is presented. The construction and performance of two versions of the “surface tensiometer,” developed for determining near-zero values of matric potential on rock surfaces, are described. Laboratory surface tensiometer measurements were made on a natural fracture surface of a Bishop Tuff block equilibrated with a water table boundary set at elevations ranging from −51 to +25 mm relative to the tensiometers. All equilibrium readings were within 10 Pa of ideal values, and most were within 5 Pa. Response times associated with this instrument-rock system were in qualitative agreement with the matric potential–dependent hydraulic properties of the rock block.

Formation, Oscillation and Deflection of Liquid Film on a Ring Frame

Image of a liquid film forming on a ring frame attached to a DuNoüy surface tensiometer was photographed with a high-speed motion picture camera. Pure water and an aqueous solution with a surfactant were used as the liquids. The formation process and the oscillation of the film were continuously recorded. Observation of the oscillations enabled us to estimate gravitational deflection of the film and the value of the surface tension.

Relation between surface activity and antibacterial activity of amine-fluorides

Amine-fluoride molecules consist of two functional groups - the organic amine, which is a surface active agent and the fluoride ion. Both ions are known to have antibacterial properties. Studies have suggested that there is a positive correlation between the antibacterial properties and the surface activity of various organic amines. The purpose of our study was to determine the antibacterial activity of the two functional groups of amine-fluoride molecules and its relationship to their surface activity. In this study, minimal inhibitory/bacteriocidic concentration (MIC/MBC) were determined for Streptococcus sobrinus 6715 at a range of pH between 5 and 7. Surface activity measurements were conducted using a surface tensiometer. Amine-fluorides were found to have similar MIC values to that of chlorhexidine digluconate at all tested pH values, thus showing high antibacterial activity against Streptococcus sobrinus 6715. The MIC values of amine-fluorides and amine-chlorides are similar, and are about 100 times lower than the MIC value of NaF. No synergistic effect was found between the fluoride and the organic amine. No correlation was found between the antibacterial properties and the surface activity of amine-fluorides. Therefore, we conclude that the antibacterial activity of amine-fluorides derives mainly from the cationic nature of the organic amine, and not from its properties as a surface active agent.

Improvement of the adhesion of low-energy polymers by a short-time plasma treatment

Foils of polyethylene, polypropylene and polyethylene terephthalate are exposed to low-pressure plasmas. The plasma is produced by microwaves ( f=2.45 GHz) at the electron cyclotron resonance, with electron densities of about 10 11 cm -3 and electron temperatures between 2 and 4 eV. Oxygen and hydrogen are used here for plasma treatment at a pressure of typically 3 Pa. Quartz-like and polyethylene-like thin films are produced on the polymers as adhesion agents. The adhesion power between the polymers and the adhesive is measured by pull-off tests. The adhesion strongly increases by a plasma treatment, for polyethylene by a factor of 20 after treatment of a few seconds. The surface tension of the polymer foils is measured using the Cahn surface tensiometer. It is shown that the polar part of the surface tension of the tested polymers increases with plasma treatment, whereas the dispersion part is only weakly influenced. The adhesion power and the polar part of the surface tension of the polymers are correlated. The polymer surfaces are investigated by scanning electron microscopy and by infrared spectroscopy.

Surface tensiometer utilizing laser-beam reflection at cylindrical liquid menisci

A surface tensiometer has been devised which is based on the mathematical solution, as a function of the surface tension of a liquid, of the profile of a cylindrical meniscus formed against a flat plate brought into contact with the free surface of a quiescent pool of the liquid. Only the angles of inclination of the meniscus at two arbitrary points are to be actually measured; the angle at each point is known accurately by observing the angle of reflection of a laser beam vertically irradiated onto the point. No knowledge of the contact angle on the plate is required. The tensiometer is suitable for the study of surface adsorption or of insoluble monolayers just the same as in the Wilhelmy plate method, but it is still superior to the Wilhelmy plate tensiometers and other conventional surface balances in its applicability to the measurements in an atmosphere completely insulated from the laboratory air. An apparatus is demonstrated that has been constructed primarily for the measurements of surface tensions of aqueous lithium bromide (LiBr) solutions with higher alcohol additives, i.e., working fluids of absorption heat pumps, under reduced pressures and elevated temperatures.

Improved differential bubble pressure surface tensiometer

An improved differential bubble pressure surface tensiometer which has increased accuracy while still being inexpensive, easy to operate, and versatile has been developed. It has potential as a valuable research tool and is capable of on-line adaptation. This tensiometer incorporates improvements over earlier differential bubble tensiometers both in design and in method of operation. Experimental results at temperatures between 120 and 300 K and at pressures to 4 MPa are presented, comparing the new method to the conventional differential capillary rise method. The results show that the improved differential bubble pressure method's accuracy is ±0.1 mN/m and its repeatability is ±0.03 mN/m. Development of the theory for the technique has led to simple methods for deriving surface tension from directly measured quantities without iterative calculations. First-order corrections for inertial and viscous effects are also presented. These become significant for systems with densities above 5000 kg/m 3 or viscosities above 1 Pa · s.

An absolute differential maximum bubble pressure surface tensiometer employing displaced capillaries

A modification of the differential maximum bubble pressure method for determining surface tensions is described. In this method, surface tension is calculated from the difference between maximum bubble pressures reached at capillaries of differing internal radii, vertically displaced by an amount calculated from the theory of Cuny and Wolf (1956) Ann Physik 17:57). The density dependence of the technique is eliminated and surface tension becomes a truly linear function of the differential maximum bubble pressure, which is easily measured. The absolute measuring technique is illustrated for equilibrium and dynamic surface tensions of a series of pure liquids and aqueous solutions. For dynamic measurements on surfactant solutions some important experimental considerations and limitations are described. In particular, a previously unrecognized source of error in estimating bubble surface ages is identified. It was found that the maximum bubble pressure for a large capillary does not immediately precede the detachment of the bubble, but occurs at one-third the overall bubble period. Thus, for large capillaries, subsequent to attaining the maximum bubble pressure, there exists a significant decay time in addition to the dead time. In general, surface ages corresponding to maximum pressure at small and large capillaries bubbling with the same period are not equal. This can lead to a large error in dynamic and equilibrium surface tensions of surfactant solutions. With suitable correction the technique is capable of measuring absolute surface tension, even for quite slowly equilibrating surfactant solutions.

Surface tension of aqueous polymer solutions

The surface tension of four kinds of aqueous polymer solutions was measured as a function of polymer concentration using a capillary tube surface tensiometer. The surface tension values of polyacrylamide solutions (Separan AP-30 and Separan AP-273) and polyacrylic acid solutions (Carbopol 934) were very close to the surface tension value of water. The surface tension values of hydroxyethyl cellulose (Natrosol 250HHR) were approximately 10% lower than the values for water. Finally, the capillary tube measurements were in good agreement with earlier measurements obtained with the maximum bubble pressure method.

Effects of hydrogen sulfide exposure on surface properties of lung surfactant

Hydrogen sulfide is an irritant and chemical asphyxiant gas that exerts its primary toxic effects on the respiratory and neurological systems. Exposure to hydrogen sulfide above a threshold value of 200-300 ppm is characterized by the sudden onset of hemorrhagic pulmonary edema. The purpose of this study was to determine whether this response is associated with changes in the surface properties of pulmonary surfactant. Bronchoalveolar lavage fluid was retrieved from the lungs of Fischer 344 rats exposed to two concentrations of hydrogen sulfide or fresh air for 4 h. Surface tension-lowering properties were assayed using a captive bubble surface tensiometer. Lung injury was assessed by histopathology and measurements of total protein and lactate dehydrogenase activity in the lavagate. Marked abnormalities in surfactant activity were demonstrated in the lavagates from rats exposed to the highest concentration (300 ppm) of hydrogen sulfide. These involved the properties of adsorption to the air-water interface and surface tension lowering under quasi-static interfacial compression. Exposure to 200 ppm hydrogen sulfide had no effect on minimum surface tension despite a significant increase in protein and lactate dehydrogenase in the lavagate. This would suggest a threshold-type response for the inhibition of surfactant activity by hydrogen sulfide. In vitro studies using normal rat surfactant showed that the abnormalities in surfactant activity were due to inhibitors in the edema fluid and not to a direct effect of sulfide on surfactant. The pathophysiological consequences of increased alveolar surface tension after hydrogen sulfide exposure may need to be considered in the clinical setting.

A captive bubble method reproduces the in situ behavior of lung surfactant monolayers

We tested a new captive bubble surface tensiometer with films adsorbed from aqueous suspensions of rabbit lung surfactant and a bovine lung surfactant lipid extract and with films of dipalmitoyl-sn-3-glycerophosphorylcholine (DPPC) spread from solvents. The lack of tubes penetrating the bubble surface eliminated potential leakage pathways for the surface film, which was compressed by increasing external pressure. Surface tensions and areas were calculated directly from bubble shapes without the need of pressure measurements. After only one to two compressions, the rabbit surfactant films exhibited the low surface tension, collapse rates, and compressibilities characteristic of the alveolar surface in situ and approached the behavior of spread DPPC films. The bubble "clicking" phenomenon described earlier by Pattle (Proc. R. Soc. Lond. B Biol. Sci. 148: 217-240, 1958) was also reproduced, but only with the bovine extract, which did not perform as well as the rabbit surfactant in surface tests. These findings suggest that surfactant apoprotein SP-A, which was probably present in the rabbit but not the bovine preparations, enhances both adsorption and stability of pulmonary surfactant monolayers.

Direct Measurement of the Attractive Force Between Individual Cooked Rice Grains of Sticky and Flaky Cultivars

ABSTRACTThe attractive force between juxtapositioned cooked rice grains of five sticky and flaky cultivars was determined using a surface tensiometer. The attractive force between the sticky grains was in the order of 800–1700 dynes and between the flaky ones, 200–1000 dynes. Increase of the water‐to‐rice ratio during cooking, in the range 0.75:1 to 1.9:1, resulted in an increase of the attractive forces. Determination of the amount of solids extracted during cooking in excess water indicated that stickiness was most probably associated with extractability.

Alternative solution for spinning drop interfacial tensiometer

An alternative solution for the spinning drop surface tensiometer is presented which is more convenient for an experimentalist to use.