Functional surfactant definition

The rate constants for the reaction of a pyridinium Ion with cyanide have been measured in both a cationic and nonlonic oil in water microemulsion as a function of water content. There is no effect of added salt on the reaction rate in the cationic system, but a substantial effect of ionic strength on the rate as observed in the nonionic system. Estimates of the ionic strength in the "Stern layer" of the cationic microemulsion have been employed to correct the rate constants in the nonlonic system and calculate effective surface potentials. The ion-exchange (IE) model, which assumes that reaction occurs in the Stern layer and that the nucleophile concentration is determined by an ion-exchange equilibrium with the surfactant counterion, has been applied to the data. The results, although not definitive because of the ionic strength dependence, indicate that the IE model may not provide the best description of this reaction system. 

Table 40 lists the most frequently reported chemical features of Mannich bases employed as surfactants, along with brief indications of their individual function, although this aspect is hardly specifiable, as several different practical definitions can be given for the same molecule. For example, an antioxidant for lubricating oil may be also named an antisludge compound, due to its capability to reduce the formation of solid precipitate caused by oxidation processes. 

The distribution constant K is expressed as a function of M, n, AG. These variables are then related to the experimental parameters which have been revealed to influence the protein partition, i.e. the pH and the surfactant concentration S. As a definition, we have ... 

Using the above mentioned straightforward method the distribution coefficient of a surfactant can be determined by measuring the surface tension of the aqueous solution after equilibration with a definite volume of the oil phase. The following Fig. 4.40 demonstrates that the distribution coefficient K is a function of temperature T, in particular for non-ionic surfactants... 

Thus, the situation is much more complex if the characteristics of the reverse micellar system (e.g., aggregation, micellar concentration, and dynamic behavior) are functions of time. In light of the available results, no definitive explanation can be offered at this time to account for the remarkable monodispersity obtained at intermediate R values, at which maximum number of nuclei is formed. Quantitative evaluation of the main features of the proposed model must await further experimental data. Of particular interest in this connection are the development of a quantitative description of the nuclei-aggregation process and the determination of surfactant aggregation numbers with water-ethanol mixtures as aqueous solubilizate. 

For ionic surfactant systems the definition of SAD as a function of flic formulation variables is... 

Definition PEG ester of palmitic acid Properties Nonionic Uses Surfactant for textile processing Trade Name Synonyms Genagen P-070 [Clariant/Functional Chems.]... 

In the case of small Brownian deformable droplets the interaction energy, when the continuous phase is a micellar surfactant solution of sodium nonylphenol polyoxy-ethylene-25 (SNP-25S), is illustrated in Fig. 8 as a function of the thickness, A, and film radius, R (see Fig. 3 for the definition of the geometry). The parameters of the micro-emulsion system are R = 2 im, d = 9.8 nm, (j> = 0.38, Ah = 5x10" J, <7= 7.5 mN/m, % = -135 mV, r = 1.91 nm, the electrolyte concentration 25 mM. The points on the contour plot (Fig. 8) correspond to tree local minima of -406 AbT, -140 k T and -37 k T corresponding to film containing 0, 1 and 2 micellar layers, respectively (Ivanov et al. 1999). These three possible films are thermodynamically stable and they act like barriers against the closer approach and flocculation (or coalescence) of the droplets in emulsions. 

Nonionics can function as cosurfactants in microemulsions. This cosurfactant role, which can also be performed by short-chain alcohols or glycol ethers, can make it possible to form microemulsions or other phases from anionic surfactant systems that would otherwise be unreachable in a pure anionic system. By one definition, a microemulsion system is one that achieves a zero or close-to-zero curvature [108]. This is easily achievable in nonionic systems, but very difficult in pure anionic surfactant systems due to the head group repulsions. Mixing the nonionic with the anionic makes these types of systems, which sometimes have greater cleaning ability, easily accomplished. 

Amphoteric surfactants are a class of chemicals whose functionality and utility to the industry is showing definite growth. As a class of surfactants, they are safe, both functional and with low irritation potentials for consumer products and, consequently, are finding increased use in personal products. The wide range of chemistries that are encompassed by this class of surfactant afford product development chemists the opportunity to tailor the performance of their products for specific applications. This is evident by the broad range of industries interested in these technologies. 

We identify the measurable change in interfacial tension, dy, with the excess in free energy per unit area due to the adsorption at the interface. This definition is assumed to hold both at equilibrium and out of equilibrium. The free energy excess can be written as a functional of the volume fraction profile of the surfactant, (p x, t), x being the distance from the interface and t the time,... 

This Monte Carlo algorithm is able to reproduce both the equilibrium and kinetic properties of a generic surfactant solution in spite of the elementary definition of kinetic constants used. Of course, to get a more detailed description of micellization kinetics, a general theory to derive the kinetic constants as function of the surfactant molecular... 

As shown by the above review of the common methods used for the determination of the CMC, a series of measurements of some property of the surfactant solution as a function of surfactant concentration is usually involved. This is followed by the detection of some characteristic point - which is called the CMC. Methodical differences may originate from the choice of the characteristic point, the kind of plot on which this point is chosen, the kind of data which are plotted and the effect of the dye. The CMC is not a very sharply defined point above which properties are qualitatively different from those below. In fact, all properties of a solution in the CMC region vary in a continuous manner and so do all of their derivatives. A micelle is by definition a reversible aggregate of a large but not infinite number of monomers. The micelle formation reaction must obey the laws of chemical equilibrium and, as such, the concentration dependence of the degree of micellization has to change gradually. Consequently, all properties of the... 

Amphoteric surfactants by definition are chimeric, exhibiting anionic character in alkaline solution, nonionic character near their isoelectric point, and cationic character in acidic solution [73]. As a result of their complex charge characteristics, their interactions with interfaces must be examined iudividually and as a function of pH. For example, the adsorption of alkyl betaines firom solution onto wool keratin is much greater at acidic than alkalide pH values. Although amphoteric surfactants are used extensively to improve the cosmetic attributes of many consmner products [74], their interactions with skin have received little attention. 

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