Surface adsorption surfactants

Surfactants may be added at low levels (i.e., 0.05% w/w in solution) for several purposes. Surfactants may aid reconstitution if the drug does wet well, and surfactants are often added to low dose products to minimize losses due to surface adsorption. Surfactants may also be effective as stabilizers in low dose protein systems. 

The third generation are latices made with independentiy prepared surfactant to mimic the in situ prepared functional monomer surfactant. These emulsifiers are often A—B block polymers where A is compatible with the polymer and B with the aqueous phase. In this way surface adsorption of the surfactant is more likely. These emulsions are known to exhibit excellent properties. 

The mechanisms that affect heat transfer in single-phase and two-phase aqueous surfactant solutions is a conjugate problem involving the heater and liquid properties (viscosity, thermal conductivity, heat capacity, surface tension). Besides the effects of heater geometry, its surface characteristics, and wall heat flux level, the bulk concentration of surfactant and its chemistry (ionic nature and molecular weight), surface wetting, surfactant adsorption and desorption, and foaming should be considered. 

Various methods have been used to examine the composition of proteins adsorbed to SAMs. Overall adsorption patterns can be examined with sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) [50, 76, 77]. Absorbed proteins are eluted from the surface with surfactant (SDS), and then separated by electrophoresis. The proteins of interest are examined by western blotting [50, 76, 77]. Protein-specific antibodies can be used to detect proteins of... 

Hydrophobic polar surfaces, adsorption of ionic surfactants on, 24 140-141 Hydrophobic precipitated silica, 22 399 Hydrophobic solvents, 16 413 Hydrophobic surfaces, 1 584-585... 

The surfactant is an important component of this process and acts to stabilize the growing polymeric particles by surface adsorption. Phase separation and the formation of solid particles occur before or after termination of the polymerization process [42]. Polymerization can occur in some systems without the presence of surfactants [40]. Various particulate systems have been prepared by this method, including poly(styrene) [43], poly(vinylpyridine) [44, 45], poly(acrolein) [46, 47], and poly(glutaraldehyde) [48-50],... 

If one adds an inorganic salt, such as NaCl, instead of detergent, then no foam is formed. Foam formation indicates that the surface-active agent adsorbs at the surface, and forms a TLF (consisting of two layers of amphiphile molecules and some water). This has led to many theoretical analyses of surfactant concentration (in the bulk phase) and surface tension (consequent on the presence of surfactant molecules at the surface). The thermodynamics of surface adsorption has been extensively described by the Gibbs adsorption theory (Chattoraj and Birdi, 1984). 

In addition to the surface adsorption properties of surfactants, they also have the remarkable ability to self-assemble in aqueous solution. The structures spontaneously formed by surfactants in solution are created... 

Thermodynamic Study of the Surface Adsorption and Micelle Formation of Mixed Surfactants... 

The Effect of Alkyl Alcohols on the Surface Adsorption and Micellization of Fluorocarbon and Hydrocarbon Surfactants... 

Surface Adsorption and molecular Areas of 111 RDH (1)-Surfactant (2) Solutions (with NaCl, Ionic Strength D.l mj at 30 C)... 

LUe may calculate the surface adsorption of pure RDH (rROH ) and pure surfactant Ic os ) corresponding to... 

Surface Adsorption of the pure Surfactant and ROH Solutions (with NaCl, ionic strength =... 

It is obvious from the data that the total surface adsorption of 1 1 mixed solution (I ) is less than the sum of the surface adsorptions of pure surfactant and RDH solutions. Similarly, rc,F (or TcioS ) is less than rc p-(or r ps") and Troh less than Froh (e.g., for 1 1 CyFNa-... 

The effect of alkyl alcohol on the surface adsorption and micellization of FC surfactant is noticeably different from HC surfactant. The molecular interactions between ROH and C7pNa in the surface layer are shown to be weaker (Smaler l jl-value) as compared with ROH-C, SNa system. 

In the case of surface adsorption, at constant surface tension ofsolutions, an equation of the same form as equation 12 is obtained for the binary surfactant mixture system (15,16) ... 

Hence the surface adsorption of surfactant 1 and 2, and their surface mole fractions can be obtained from the surface (interfacial) tension-concentration relationships (Fig.1 and fig.2) by applying the Gibbs adsorption equation. 

The nature of surface adsorption and micelle formation of various mixed FC- and HC-surfactants systems can be conveniently and well investigated by the non-ideal solution theory semi-emplrlcally applied in the surface layer and micelles. The weak "mutual phobic" interaction between FC- and HC-chains has been clearly revealed in the anionic-anionic and nonlonic-nonionic systems as Indicated by the positive values. value cannot be obtained... 

It is evident that the non-ideal solution theory of surface adsorption and micellization is a convenient and useful tool for obtaining the surface and the micelle compositions and for studing the molecular interaction in the binary surfactant system. 

The flotation of minerals is based on different attachment forces of hydrophobized and hydrophilic mineral particles to a gas bubble. Hydrophobized mineral particles adher to gas bubbles and are carried to the surface of the mineral dispersion where they form a froth layer. A mineral is hydrophobized by the adsorption of a suitable surfactant on the surface of the mineral component to be flotated. The hydrophobicity of a mineral particle depends on the degree of occupation of its surface by surfactant molecules and their polar-apolar orientation in the adsorption layer. In a number of papers the relationship was analyzed between the adsorption density of the surfactant at the mineral-water interface and the flotability. However, most interpretations of adsorption and flotation measurements concern surfactant concentrations under their CMC. 

In this paper we apply basic solution thermodynamics to both the adsorption of single surfactants and the competitive adsorption of two surfactants on a latex surface. The surfactant system chosen in this model study is sodium dodecyl sulfate (SDS) and nonylphenol deca (oxyethylene glycol) monoether (NP-EO o) These two surfactants have very different erne s, i.e. the balance between their hydrophobic and hydrophilic properties are very different while both are still highly soluble in water. 

Our aim, however, is to find a model that is as simple as possible and yet makes it possible to estimate adsorption from surfactant mixtures within experimental error in the type of systems investigated by us, i.e. adsorption at coverages approaching monolayers on essentially hydrophobic surfaces, the surfactants adsorbing with their... 

Surfactant Prevent/control aggregation, particle formation and surface adsorption of drug Examples include polysorbate 20 and 80 Employed if aggregation during the lyophilization process is an issue May serve to reduce reconstitution times Examples include polysorbate 20 and 80... 

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