Measurement tensiometry

According to Duchene et al. [17], when tensiometry is used to measure the maximum detachment force as a function of the displacement of the upper support (function of the joint elongation), the work of bioadhesion can be defined as in Eq. (7). 

The values of Ys> Yw> Ysw were measured by spinning drop interfacial tensiometry (SDIT) as described in the Experimental Section. The values of Y Y s were obtained by the SDIT method using a polyethylene glycol (PEG), Jeffox PEG-300... 

Rhodococcus rhodochrous was used for the hydrolysis of both granular PAN and acrylic fibers by nitrile hydratase and amidase (Tauber et al., 2000). Similarly, Agrobacterium tumefaciens (BST05) was found to convert polyacylonitrile into polyacrylic acid by nitrile hydratase and amidase (Fischer-Colbrie et al., 2006). Nitrilase was also used for the surface hydrolysis of PAN from Micrococcus luteus BST20 (Fischer-Colbrie et al., 2007). However, polyamidase from Nocardia farci-nica leads to an increase of polar groups on the surface of PA, which was measured by tensiometry (Heumann et al., 2009). 

D. O. Johnson, and K. J. Stebe, Oscillating bubble tensiometry A method for precisely measuring the kinetics of surfactant adsorptive-desorptive exchange. J. Colloid Int. Sci. 168 526-538 ( 994). 

A.I. Rusanov, V.A. Prokhorov, Interfacial Tensiometry, Elsevier (1996). (Although this book emphasizes measurements of surface and interfacial tensions, it also contains much interesting information on thermodyncimic backgrounds and interpretations.)... 

The aggregation behavior of selected dibiock copolymers with various compositions was investigated applying several techniques, such as polarized optical microscopy (POM), tensiometry measurements, fluorescence studies, deuterium NMR spectroscopy, SAXS measurements, and cryogenic TEM [4, 5]. In systematic studies we particularly focused on the effect of an increase in the dimethylsiloxane chain length on the aggregation behavior of the investigated surfactants. 

It is noteworthy and interesting that both the tensiometry and the fluorescence measurements give an order of CAC values for the series of copolymers with 4, 6 and 10 DMS units that is opposite to the expected order. The usual trend for surfactants is that the aggregation, which is usually micelle formation, starts at lower concentration the longer the hydrophobic tail. With the dimethylsiloxane sur ctants studied in this work, the trend is the opposite. We believe the reason for this is that we observe the formation of vesicles instead of micelles. (Vesicles are dispersions of a lamellar phase in water.)... 

Evidence for dimerization of the hydroxoaqua ion is based on the decrease of the number of chromium particles in reaction 10 and its increase in reaction 11. The number, v, of discrete chromium particles per diaqua ion should decrease from v = 1 to v = as the diaqua ion is titrated with 1 mol of OH" and then rise again to v = 1 as a second mole of OH" is added, v may be determined by measuring a colligative property of the solution. A most suitable method for ionic solutes is Three-Phase Vapor Tensiometry, TPVT i The three-phase solvent system consists of a saturated solution of an electrolyte in water, in equilibrium with the crystalline phase of that electrolyte and with water vapor. An isobaric temperature difference (AT)p is established when the pure solvent is equilibrated with a solution of a foreign solute in the same solvent, at constant pressure. The apparent number, Vm of free particles per formula of solute depends on the molality of the solute (m), the three-phase ebulioscopic constant Kg, and (AT)p... 

Powder tensiometry, where the powder solid is brought into contact with a testing liquid and the mass of liquid absorbed into the solid column is measured as a function of time. 

On the other hand, the powder tensiometry method can be applied with any Wilhelmy type tensiometer. A special thin glass tube, which has a porous plug at the bottom, is filled with the powder which will be tested and the powder column is then brought into contact with the testing liquid. The mass of liquid absorbed into the porous solid is measured as a function of time by means of an electrobalance. The amount absorbed is a function of the viscosity, density and surface tension of the liquid, the material constant of the solid, and the contact angle of the interaction, as given in the following relationship ... 

A variety of techniques including rising height and contact angle measurements, the drop dissipation test and tensiometry have been used to quantify increases in hydrophilicity [48, 49, 53, 57, 67]. For example, treatment of PET fabrics with a T.fusca cutinase and T. lanuginosus lipase lead to a wetting time of 120 s and 100 s, respectively, compared with 45 2 min for the untreated material [24]. 

The polymerization process was firstly monitored by tensiometry (Figure 1). At the beginning no surface pressure was measured indicating that coniferyl alcohol is not surface active. After peroxidase and hydrogen peroxide spreading, the surface pressure increases indicating the formation of an interfacial layer. After 6-8 hours, the surface pressure levels off around 9 mN/m and then tends to decrease. This behaviour can be explained by a desorption of the molecules from the interface to the bulk or by a change of the interfacial layer structure. 

About 150 years ago Simon [174] proposed the maximum bubble pressure method for measurements of surface tensions of liquids. Due to technical problems, this method was believed to be unreliable. During the last 20 years, however, more than 200 publications have been published on theoretical and experimental aspects of the bubble pressure tensiometry making this method to the most frequently used one for the very short adsorptions times from few milliseconds to some seconds. One of the advantages of this technique is the small amount of liquid required for the surface tension measurements, which is particularly important in studies of biological liquids [175]. 

The capillary pressure tensiometry (CPT) method has been developed for measuring the interfacial tension of pure liquids and is based on the simple relationship for the capillary... 

The two methods maximum bubble pressure and profile analysis tensiometry complement each other experimentally and cover a total time range of nine orders of magnitude from about lO" seconds up to 10 seconds (many hours). The example given in Fig. 33 shows the dynamic surface tension of two Triton X-100 solutions measured with the instruments BPA and PAT (SINTERFACE Technologies) over the time interval of 7 orders of magnitude. As one can see, the experiments cover the beginning of the adsorption process and the establishment of the equilibrium state. 

Interfacial tensiometry is technique which is sensitive to the adsorption of surface-active solutes. The time-dependent interfacial tension measurements served to reveal the physico-chemical changes at oil/aqueous interface during mass transfer of demulsifiers and demulsifier mixtures to the interface. The apparent spreading rate which was determined from the time-dependent tensions provided a measure for the ease of deformation of the interface and the speed of adsorption to the interface. The apparent spreading rate parameter correlated very well with the coalescence behavior and dewatering efficiency of the emulsion. 

There are a variety of simple and inexpensive techniques for measuring contact angles, most of which are described in detail in various texts and publications and will be mentioned only briefly here. The most common direct methods (Fig. 17.4) include the sessile drop (a), the captive bubble (b), the sessile bubble (c), and the tilting plate (d). Indirect methods include tensiometry and geometric analysis of the shape of a meniscus. For solids for which the above methods are not applicable, such as powders and porous materials, methods based on capillary pressures, sedimentation rates, wetting times, imbibition rates, and other properties, have been developed. 

Immiscible displacement in single capillaries The Interfacial Displacement Tensiometry results for the pure oil/water systems described previously demonstrate that the simple theory outlined earlier is capable of describing the experimental results satisfactorily. This approach extended to the surfactant solution systems results in measured values of interfacial tension, as described before. These tensions differ from their equilibrium values, so that a better understanding of their behavior is dependent on as full as possible analysis of the factors involved ... 

Details are given of the synthesis of nanosize PS particles by miniemnlsion polymerisation. The effect of varying the surfactant concentration on interfacial tension and colloidal stability was examined. Surface tensiometry was nsed to monitor the aqneons phase surfactant concentration via a calibration curve. TEM was used to confirm particle diameters and to measure the particle size distributions. 8 refs. 

The HT voltammetry with gold electrodes was also recently used to measure the surface partitioning constant of a soluble, redox-active surfactant at the air/water interface [25]. Malec and coworkers modified the surface of gold electrodes by self-assembly of short alkane chain thiols in order to mimic the thermodynamic properties of the air/water interface. They relied on the fact that the surface tensions of the air/water interface and of the liquid alkane/water interface are similar [8]. Indeed, the HT measurements of the Gibbs monolayer formation constant were in agreement with their surface tensiometry and Brewster angle microscopic measurements [25]. 

Contact angle measurements or surface tensiometry allow determination of surface energy or surface tension on polymer brushes (85). It also gives information on differences in morphology and fiinctional group distribution... 

The aim of the work presented is to evaluate the physiological status of tracheal aspirate from infants with NRDS before and after Curosurf therapy via interfacial tensiometry. The measurements are made by the pendant drop method, which requires a minimal volume of the clinical samples. 

The surface energy of PDMS films was determined by wettability measurements. Equilibrium contact angles of drops of water (a polar liquid) and diiodomethane (a nonpolar liquid) were measured with an automated Kruss apparatus. Contact-angle hysteresis (difference between receding and advancing angles) was measured for water and diiodomethane by a tensiometry technique (speed of 10 mm/min, immersion length equal to 7 mm). 

FIGURE 19.1 Dynamic surface-tension data for n-alkyldimethylphosphine oxides, as measured by maximum bubble-pressure technique (O), drop-volume tensiometry ( ), and de Nolly ring tensiometry (A), and model fit ignoring reorientation (dotted line) and incorporating reorientation (solid line). (From Fainerman, V. B., et al. 2000. Adv. Colloid Interface Sci. 86 (1-2) 83-101. With permission.)... 

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