Dynamic Surface Tension Behavior Research Articles

Effect of Sodium Halide on Dynamic Surface Tension of a Cationic Surfactant

AbstractThe equilibrium and dynamic surface tension (DST) of the novel cationic surfactant, 3‐(p‐nonylphenoxy)‐2‐hydroxylpropyl trimethyl ammonium bromide, abbreviated as RTAB, were studied. The effect of sodium halide such as NaCl, NaBr and NaI on the DST behavior of the RTAB solution below its CMC was studied in detail. Due to the preferential adsorption, the effect of hydration and salting out, the ability to reduce the DST values at the same concentration was in the order of NaI>NaBr>NaCl. Attributed to its high surface activity, the equilibrium time of the DST of the surfactant solution was insensitive to the ionic strength.

Equilibrium and Dynamic Surface Tension Properties of Aqueous Solutions of Sulfonated Cationic‐Nonionic Fluorocarbon Surfactants

The equilibrium and dynamic surface tension properties in aqueous solutions of nonionic and cationic fluorinated surfactants bearing a sulfonated group are reported. Both surfactants show low critical micellar concentration and very low equilibrium surface tension values, but the cationic surfactant is more effective at decreasing surface tension, which is attributed to a small surface area per molecule. In dynamic surface tension measurements both surfactants show an induction time, which is longer for the nonionic surfactant with a higher molecular weight, slower diffusion rates, and higher molecular surface area. The dynamic behavior of surface tension is modeled by a series of exponentials from which a relaxation time for surface tension decay can be estimated. This relaxation time is faster for the cationic surfactant and decreases with both surfactant concentration and temperature. In mixtures of both surfactants, the values of the relaxation time are between those of the pure surfactants, indicating neither synergism nor antagonism.

Additive Adsorption and Interfacial Characteristics of Nucleate Pool Boiling in Aqueous Surfactant Solutions

Interfacial phenomena and ebullient dynamics in saturated nucleate pool boiling of aqueous solutions of three surfactants that have different molecular weight and ionic nature are experimentally investigated. The additive molecular mobility at interfaces manifests in a dynamic surface tension behavior (surfactant adsorption–desorption at the liquid–vapor interface), and varying surface wetting (contact angle) with concentration (surfactant physisorption at the solid–liquid interface). This tends to change, enhance, and control the boiling behavior significantly, and an optimum heat transfer enhancement is obtained in solutions at or near the critical micelle concentration (CMC) of the surfactant. Furthermore, wettability (contact angle) is observed to be a function of the molecular makeup of the reagent, and shows distinct regions of change along the adsorption isotherm that are associated with the aggregation mode of adsorbed ions at the solid–water interface. This distinguishably alters the ebullience from not only that in pure water, but also between pre- and post-CMC solutions. Increased wetting tends to suppress nucleation and bubble growth, thereby weakening the boiling process.

Study of the Surface Tension of the Aqueous Solutions of Dodecylamidoethyldimethylbenzylammonium Chloride

The dynamic and equilibrium surface tensions of aqueous dodecylamidoethyldimethylbenzylammonium chloride solutions of various concentrations at 16, 20, 25, 30, and 35°C are studied for the first time. The effects of the concentration and temperature on the surface tension relaxation are discussed. The possibility of two-dimensional phase transition and its effect on the dynamic behavior of surface tension are considered.

Dynamic Adsorption and Surface Tension of Aqueous Dilauroylphosphatidylcholine Dispersions under Physiological Conditions

The dynamic surface tension and equilibrium adsorption behavior of DLPC dispersions in phosphate buffer saline at 37 and 25 degrees C was studied with tensiometry, infrared reflection--absorption spectroscopy (IRRAS), and ellipsometry. The results are compared with those in water (Pinazo et al. Langmuir 2002, 18, 8888). Even though the pH and salinity have no apparent effect on the equilibrium surface tension and the surface pressure--area isotherm, they affect the dynamic surface tension by decreasing the adsorption rate and increasing the dynamic tension minima at a pulsating area of 20 or 80 cycles per minute. Moreover, IRRAS and ellipsometry results show that the adsorbed layers and the spread monolayers have larger area per molecule, or looser packing, in buffer than in water. A new hypothesis is proposed to elucidate the effect of pH/salinity on this zwitterionic surfactant: there is some specific interaction or binding between the ions from the buffer saline with the polar headgroups of DLPC. This interaction induces stronger intermolecular repulsions of the surfactant layer in buffer than that in water, despite the expected electrostatic screening effect, and causes higher dynamic surface tensions. The results have implications in designing lung surfactant replacement formulations.

Dynamic Surface Tension of Polyelectrolyte/Surfactant Systems with Opposite Charges: Two States for the Surfactant at the Interface

The molecular reorientation model of Fainerman et al. is conceptually adapted to explain the dynamic surface tension behavior in polyelectrolyte/surfactant systems with opposite charges. The equilibrium surface tension curves and the adsorption dynamics may be explained by assuming that there are two different states for surfactant molecules at the interface. One of these states corresponds to the adsorption of the surfactant as monomers, and the other to the formation of a mixed complex at the surface. The model also explains the plateaus that appear in the dynamic surface tension curves and gives a picture of the adsorption process.

Dynamic surface tension measurements of molten Sn/Pb solder using oscillating slender elliptical jets

The present study investigates the dynamic surface tension of molten 63%Sn–37%Pb eutectic solder at timescales 1–3 ms applicable to solder jetting applications in microelectronics manufacturing. The oscillating jet method is employed to measure the surface tension of the melt when ejected into nitrogen atmospheres containing controlled amounts of oxygen from 15 ppm to 21% (mol). Typical jet ejection conditions correspond to We=0.16, Re=49, and Fr=165. The molten solder is steadily forced through an elliptical capillary (aspect ratio of ∼2), thus forming a stationary oscillating jet. The shape evolution of the jet is affected by the liquid/gas interface properties and is used, along with an existing theoretical model, to determine the surface tension of the liquid metal as a function of distance (likewise, surface age) from the orifice. The experimental data reveals dynamic surface tension behavior at 3700 ppm O 2 concentration, and indicates a characteristic time below 1 ms for the molten-metal surface to be saturated by adsorbed oxygen at ambient O 2 concentrations of 1% or higher. Mass diffusion in the gas phase is found to be the rate limiting process controlling oxygen adsorption on the solder melt surface. The results provide crucial information needed to reduce solder surface degradation, which hampers the successful implementation of solder jetting technology.

Determination, by dynamic surface-tension analysis, of the molar mass of proteins denatured in guanidine thiocyanate.

A drop-based dynamic surface-tension detector (DSTD) has been used to study the dynamic surface tension behavior of proteins denatured in guanidine thiocyanate (GndSCN). The dynamic surface tension at the air-liquid interface is obtained by measuring the internal pressure of drops that grow and detach at a specified rate. In the method the sample of interest is injected and subsequently flows to the DSTD-sensing capillary tip. For this work, a novel DSTD calibration procedure utilizing two distinct mobile phases is applied. Here, the mobile phases are aqueous with different constituents, for example GndSCN and phosphate buffer, either added or omitted. The dual-mobile phase calibration procedure gives the analyst the capability of making protein measurements in a GndSCN-phosphate buffer mobile phase, while measuring a calibration standard in another mobile phase, such as water, in which the surface tension of the calibration standard is readily available. Results are presented with drop volumes of either 2 microL (i.e. 2-s drops) or 7 microL (i.e. 7-s drops) for proteins varying in molar mass from 12,000 to 330,000 g mol(-1). We demonstrate that the DSTD can be used to determine the molar mass of proteins denatured in GndSCN. The method applies a regime where the denatured protein is detected by surface-active properties, and selectivity with regard to molar mass is contained in the dynamic component of the DSTD signal. The dynamic surface pressure signals of the denatured proteins suggest that diffusion plays a large role in the kinetics of the surface activity. The limit of detection for the denatured proteins studied ranged from 3 mg L(-1) to 14 mg L(-1). The DSTD, coupled with the novel dual-mobile phase calibration procedure, can be used to investigate the fundamental properties of proteins. Insight into the behavior at the air-liquid interface for native and denatured proteins is achieved; this is a novel tool for studying protein denaturation, complementary to other common approaches such as spectroscopy and calorimetry. Furthermore, the reported method could be widely applied to the study of effects on the interfacial properties of proteins after a variety of chemical and physical modifications that are possible with the dual-mobile phase calibration procedure.

Dynamic Surface Excesses of Fluorocarbon Surfactants

Dynamic adsorption and surface tension behavior of aqueous fluoro-surfactant solutions has been investigated using a range of experimental techniques, including neutron reflection (NR). Equilibrium tensions, γeq, have been measured by drop volume tensiometry (DVT), and dynamic surface tensions, γdyn, have been determined using the nonperturbative method, surface light scattering (SLS). Dynamic conditions for NR and SLS measurements were established using an overflowing cylinder (OFC). The OFC provides a dynamic surface on the 0.1−1 s time scale and offers a large (∼50 cm2), near flat surface for interrogating interfacial properties. To exploit these techniques effectively, a fluorocarbon anionic surfactant, sodium bis(1H,1H-nonafluoropentyl)-2-sulfosuccinate (di-CF4) has been specifically selected. Molecular structure effects have been explored with the C6 analogue sodium bis(1H,1H,7H-dodecafluoro-n-heptyl) sulfosuccinate (di-HCF6). Using OFC−NR, dynamic surface excesses, Γdyn, have been measured directly...

Dynamics of Polymer−Surfactant Complexes: Elongational Properties and Drop Impact Behavior

The extensional and dynamic surface tension properties of a set of associative polymer-surfactant Boger fluids have been characterized. When combined with the already understood structural phenomena of this anionic surfactant-nonionic polymer complex, the results of this study provide great insight into the benefits of utilizing polymer-surfactant complexes to tune fluid properties during rapid, high-deformation processing scenarios. The dynamic surface tension behavior observed for the associative polymer-surfactant mixture investigated elucidates new insights into the enhanced surface adsorption of the complex to the air-water interface over that of the pure-component solutions alone at concentrations below the commonly referenced critical aggregate concentration (cac) of the complex. The dynamics of extension of this set of constant-viscosity elastic (Boger) fluids were seen to change substantially as increasing amounts of associative surfactant were present in solution, with the polymer-surfactant solutions displaying faster rates of strain hardening at lower rates of extension than the pure polymer solution. Such significant changes to the dynamics of extension of these dilute polymer solutions upon the addition of an associative surfactant are shown to be responsible for the observed recoil suppression during a drop impact-event on a hydrophobic surface. The enhancement of extensional properties of the solution at lower extension rates far outweighs the advantages provided by the presence of fast-acting surfactants at the air-water interface. These outcomes provide detailed evidence that significant synergy remains to be explored with respect to drop impact behavior and the addition of associating surfactants to dilute polymer solutions in industrial formulations.

Inhibitory effects of fibrinogen on the dynamic tension-lowering activity of dipalmitoyl phosphatidylcholine dispersions in the presence of tyloxapol

Inhibitory effects of fibrinogen on the dynamic surface tension-lowering ability of dipalmitoyl phosphatidylcholine (DPPC)/tyloxapol dispersions at pulsating air/liquid interfaces were investigated. When 10 ppm tyloxapol was added into a 1000 ppm DPPC dispersion prepared by sonication alone, the dynamic surface activity of the mixture was controlled by DPPC and was significantly inhibited by the presence of 1000 ppm fibrinogen. If the added tyloxapol concentration was as high as 100 ppm, tyloxapol then dominated the dynamic adsorption behavior of the dispersion, and the addition of 1000 ppm fibrinogen only showed minor influence on the dynamic surface tension behavior. When a 1000 ppm DPPC dispersion was prepared by sonication with 10 ppm tyloxapol, improved dynamic adsorption behavior resulted and thus the fibrinogen inhibition on the dynamic surface tension-lowering activity of the dispersion was slightly lessened. If the concentration of tyloxapol present during the sonication of a 1000 ppm DPPC dispersion was increased to 100 ppm, less interference by tyloxapol and/or fibrinogen with the dynamic adsorption of DPPC was found, which appears related to the tyloxapol-enhanced DPPC dispersion status with a reduced particle size.

Dynamic Surface Tension Behavior of a Mixed Insoluble/Soluble Surfactant Dispersion at Pulsating Air/Liquid Interfaces: Roles of the Soluble Surfactant

The influence of tyloxapol on the dynamic surface tension response of dipalmitoyl phosphatidylcholine (DPPC) dispersions at pulsating air/liquid interfaces was investigated. For a 1000 ppm DPPC dispersion prepared by sonication with a larger particle size, the dynamic surface activity of DPPC was strongly affected by the addition of 100 ppm tyloxapol. With a longer sonication time or smaller particle size, the DPPC inactivation was still observed but was somewhat less significant, resulting in slightly lower dynamic surface tensions. If a DPPC dispersion was sonicated in the presence of tyloxapol, the particle size of DPPC was greatly reduced by tyloxapol and the inhibitory effect of tyloxapol on the dynamic adsorption of DPPC may be significantly diminished. The results suggest that the competitive adsorption of tyloxapol may have a detrimental effect on the dynamic surface tension lowering ability of a DPPC dispersion with the extent depending on the DPPC dispersion state. Nevertheless, the dynamic surface activity of DPPC may be enhanced through the improved dispersion by tyloxapol if an appropriate preparation protocol is applied, and the inhibitory effect of tyloxapol may be reduced or overcome.

Foaming and dynamic surface tension of aqueous polymer/surfactants solutions 1: ethyl(hydroxyethyl) cellulose and sodium dodecyl sulphate

Foaming (in a column) and dynamic surface tension behaviour of aqueous solutions of sodium dodecyl sulphate (SDS), and ethyl (hydroxy ethyl) cellulose/sodium dodecyl sulphate (EHEC/SDS) mixtures was determined. The results indicated a synergism in foaming and surface activity for the EHEC/SDS mixtures over a specific concentration range. For the SDS solution, the maximum value in Marangoni elasticity ( E m max ), as determined from dynamic surface tension data, was reached within a surface age of 0.05 s and it could be suggested that in this case E m max was relevant to foam stability. However, for the EHEC (nonfoaming solutions), E m max was reached after longer surface ageing periods (0.05–0.1 s). For the EHEC/SDS solutions, E m max occurred over a range of surface ageing periods depending on the polymer/surfactant ratio and no correlation was obtained between E m max and foaming. The E m max time lag for the polymer and polymer/surfactant mixtures was explained by the slower diffusion from solution to the new surface. For the EHEC/SDS, the enhanced the foaming behaviour was explained by the adsorption of surface active polymer/surfactant (clusters) species at the air/solution interface. It was suggested that this could lead to coherent (gelatinous) interfacial layers in the thin film lamella which reduce drainage.

Exogenous surfactant as a drug delivery agent

Pulmonary surfactant is a complex mixture of lipids and several specific surfactant proteins, which together render it with unique spreading properties and a dynamic surface tension behavior. These characteristics are heralded as ideal for a carrier of choice to instil therapeutic agents into the lung, because this combination enables high local therapeutic levels while minimizing systemic side-effects of the instilled agent. This review outlines the rationale to use exogenous surfactant in lung injury, including opening-up inaccessible regions of the lung to other therapeutic agents. Especially the combination of anti-microbial agents and surfactant offers an alternative for critically ill patients with pneumonia. Some caution is also indicated in combining surfactant with antibiotics without proper evaluation of possible interactions. Some other applications for surfactant as a carrier are discussed. Overall, the benefits of surfactant as a carrier warrants clinical trials and promises additional therapeutic tools for the clinician.

Inhibitory effects of tyloxapol on the surface activity of albumin at the air/liquid interface

This study investigated the inhibitory effects of tyloxapol on the albumin surface activity at the air/liquid interface. Dynamic surface tensions under constant-area and pulsating-area conditions for mixed albumin/tyloxapol solutions were measured by using a drop volume tensiometer and a pulsating bubble surfactometer. The dynamic surface tension behavior under constant-area conditions demonstrated that by adding 1 ppm tyloxapol to a 5 ppm albumin solution, the long-time adsorption behavior or equilibrium surface tension behavior was strongly affected, but the surface activity of albumin was not inhibited significantly. However, at higher tyloxapol concentrations, such as 100 ppm, the inhibitory effect of tyloxapol on the albumin surface activity was clearly observed, even the albumin concentration was as high as 50 ppm. As for the dynamic surface tension behavior of 5 or 50 ppm albumin solutions under pulsating-area conditions, the dynamic surface tensions were not affected if only 1 ppm tyloxapol was present in the subphase. However, the tyloxapol-dominated dynamic surface tension behavior was observed if 100 ppm tyloxapol was added. The results suggest that the albumin surface activity or adsorption could be inhibited if appropriate amounts of tyloxapol are present, which might be applied to prevent the deleterious effect of albumin on the surface tension-lowering ability of lung surfactants.

The Use of Principal Component Analysis to Classify PDMS Surfactants Used to Make Rigid Polyurethane Foams Based on Their Dynamic Surface Tension Characteristics

Polydimethylsiloxane surfactants are well known in the polyurethane industry. They play a vital role in the manufacture of both rigid and flexible foams. In order to achieve the phaseout of CFCs, as prescribed in the Montreal protocol, new blowing agents have been developed to make polyurethane foams. This has been accompanied by changes in the composition of the foam forming material including the silicone surfactants. This article describes a method for measuring the dynamic surface tension behavior of these silicone surfactants in model liquids representative of the polyol component in the foam forming mixture. The different dynamic surface tension characteristics of commercially available silicone surfactants are reported. In a second stage these data are analyzed using a chemometrics technique called principal component analysis. This allows the classification of the various surfactants in several subsets, each characterized by a specific dynamic surface tension behavior. The combined method of dynamic surface tension measurements and principal component analysis allows fast screening of surfactants used in the polyurethane industry.

Differences between Dynamic and Equilibrium Surface Tension of Poly(oxyethylene)–poly(oxypropylene)–poly(oxyethylene) Block Copolymer Surfactants (Poloxamers P407, P237, and P338) in Aqueous Solution

Poloxamer surfactants are macromolecules with complex interfacial behavior. Although a number of studies of equilibrium surface tension have been published recently, there is little information on the diffusion of these large molecules to the air–liquid interface. Because most surfactants are used in dynamic systems, the diffusion to the surface can be critical in controlling performance. In this study a maximum bubble pressure method was used to study dynamic surface tension (DST) of Poloxamer P407, P237, and P338, at a range of bubble rates (surface age) and concentrations, at either 25 or 35°C. The DST did not change at the critical micelle concentration and also did not vary in the same manner as the equilibrium surface tension (EST) with respect to temperature. It was concluded that DST behavior of the surfactants was most closely related to the poly(oxyethylene) content and/or total molecular weight of the surfactants, whereas the micellization and hence the EST were more closely related to the poly(oxypropylene) content.

Equilibrium and dynamic surface tension behavior of aqueous soaps: sodium octanoate and sodium dodecanoate (sodium laurate)

Abstract The dynamic surface tension behavior of sodium salts of fatty acids having eight (sodium octanoate) and twelve (sodium laurate) carbon atoms in pure water or in 0.1 N aqueous NaOH has been studied. The primary reason for this study was to obtain fundamental knowledge of the tension behavior of these molecules which are present in several consumer products. Tension data were obtained at a concentration of 30 mM for octanoate and 0.5–10 mM for dodecanoate at 25 and 37°C with the pulsating bubble surfactometer at constant or pulsating areas. In addition, the spinning bubble tensiometer and the Wilhelmy plate/Langmuir trough methods were used for better establishing reliable values of equilibrium tensions. An oscillating jet apparatus was used for obtaining estimates of tensions at small time-scales (3–10 ms). From these measurements, the most important factors affecting the dynamic tension behavior were the soap solubility, chain length, the aqueous medium, and the concentration. The equilibrium tension of aqueous sodium octanoate was determined to be about 40 mN m−1. Sodium octanoate was found to be very slow to equilibrate, with a time-scale of about 1000s. Aqueous sodium laurate has a longer chain length and is much faster to adsorb and more surface-active. The equilibrium tension was 23 mN m−1, and the time-scale of equilibration was very short. When tested in 0.1 N aqueous NaOH, sodium laurate showed much higher tensions. The tensions decreased with increasing concentration, as expected, and more strongly at the higher temperature.

Hexadecanol Microstructures of Crystallites in Aqueous Dispersions and of Langmuir-Blodgett Monolayers

The effects of the dispersion preparation protocol on the microstructures of n-hexadecanol crystallites were examined. Dispersions of hexadecanol were prepared in saline at 25 °C with different thermal and mechanical agitation histories. The structures of the dispersed crystallites were probed by Fourier transform infrared spectroscopy (FTIR) and powder X-ray diffractometry on more concentrated systems. Dry crystals, crystals previously melted without water present, and crystals simply mixed with saline had one crystalline structure(β 2 ), which is the stable structure for solid hexadecanol. By contrast, crystals which were previously melted in saline showed a second coexisting crystalline structure (α or β 1 ), which apparently contains some water of hydration, as indicated by the relative infrared absorbance of its OH bands. The structures of Langmuir-Blodgett (LB) monolayers at various surface pressures (10-50 mN/m) were also probed by FTIR. The monolayers, which were in the solid monolayer state, had a different (probably hexagonal) microstructure and a higher molecular mobility than the three-dimensional crystallites. Moreover, the LB monolayer surface density was quite independent of the surface pressure, as expected from the steepness of the surface pressure-surface area monolayer isotherm. The average molecular orientations of the hydrocarbon chains and dipole moments were calculated from the dichroic ratios with a theory for ultrathin films. The hydrocarbon chains were oriented uniaxially, and the average chain tilt angle from the surface normal was 35°. The results on the effects of dispersion preparation protocol on microstructures of crystallites can be used in further understanding the dynamic surface tension behavior of these dispersions

Dynamic surface tension behavior of hexadecanol spread and adsorbed monolayers

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDynamic surface tension behavior of hexadecanol spread and adsorbed monolayersSun Young Park, Chien Hsiang Chang, Dong June Ahn, and Elias I. FransesCite this: Langmuir 1993, 9, 12, 3640–3648Publication Date (Print):December 1, 1993Publication History Published online1 May 2002Published inissue 1 December 1993https://doi.org/10.1021/la00036a047RIGHTS & PERMISSIONSArticle Views237Altmetric-Citations23LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alerts Get e-Alerts