Charged surfactants

The effect of surfactant charge on the reaction rate was investigated for a related reaction, ring opening of 1,2-epoxyoctane with sodium hydrogen sulfite (Scheme 2 of Fig. 2). The reaction, which was performed in a Winsor III microemulsion, was fast when a nonionic surfactant was used as the sole surfactant and considerably more sluggish when a small amount of SDS was added to the formulation [9]. 

Equation (2) for the number of particles per unit volume of aqueous phase has one undetermined parameter Af which is the difierence between the surfactant charged and the surfactant adsorbed on the surface of the polymer particles. 

While it is a powerful solvent, DMSO is undesirable for industrial use. Instead, the surfactant Triton X-100 can be an effective replacement for DMSO in enzymatic hydrolyses [14], and in our case, worked very well. Triton X-100 forms micelles when mixed with water and would solubilize low concentrations of ester for hydrolysis. However, increasing the surfactant charge did not accelerate hydrolysis. In an attempt to reduce the somewhat long reaction time, we screened the enzymes Amano PS Lipase XIII, Pseudomonas jluorescens and Candida cylindracea versus Amano PS-30. PS-30 was still considered the best choice of enzyme when... 

Surfactants are major industrial products with millions of metric tons produced annually throughout the world. Table 1-1 lists surfactant consumption in the United States and Canada for the year 2000. Table 1-1A shows consumption of the various surfactant charge types by percentage Table 1-1B, consumption of the five major types of surfactant by tonnage. 

The type of emulsion stabilized by polymeric surfactants, charged or uncharged, was not investigated in detail, although it has long been understood that it was dependent of the structure of the surfactant macromolecules. In a series of papers, Riess and his coworkers [143-145] have investigated the effect of the composition and architecture of PS-PEO-based block copolymers (PS polystyrene PEO polyethylene oxide) on stability and emul-... 

Classification of the major supramolecular templating routes according to surfactant charge... 

Surfactant charge Surfactant type Interaction type Examples/structures... 

L-valinate, N-dodecoxycarbonylvaline), polymer surfactants (e.g. poly[sodium N-undecenyl-L-valinate]), and n-alkyl-P-glucopyranosides. An important property of the glycosidic surfactants is that they can be charged in situ through complexation with borate anions, which allows the surfactant charge density to be adjusted to optimize enantioselectivity [204]. 

Other theoretical models of surfactant adsorption kinetics take into account specific experimental conditions or surfactant properties surfactant charge [27, 28, 29, 30, 31, 32, 33], micelle formation [34, 35, 36, 37, 38] or other specific effects [39, 40, 41, 12, 13, 42, 43]. These other effects however will not further discussed here, as most of the surfactants studied in literature turned out to follow a diffusion mechanism. Thus, below we will give more details mainly on models based on a diffusion mechanism. 

This short discussion of problems associated with stabilizing dispersions of PVAc and its copolymers leads to the conclusion that the hydrophilic nature of VAc make placement of stabilizing species (surfactant, charge, hydrated layer, etc.) difficult without incurring additional problems (decrease in rate of polymerization, increase in the concentration of water-soluble oligomers, increase in viscosity, etc.). As a result, a combination of approaches is often used in commercial latex production. The need for better surfactants, especially reactive surfactants, for the emulsion polymerization of vinyl monomers is still evident... 

Brackman, J. C. and J. B. F. N. Engberts (1992). Effect of surfactant charge on polymer-micelle interactions -Dodecyldimethylamine oxide. Langmuir 8(2) 424-428. 

Ionic Nature Anionic/nonionic Uses Surfactant charge soap for dry cieaning Ablupol DSC [Taiwan Surf.]... 

Figure 10.14. Surface charge reversal by surfactant adsorption (a) native surface (charges omitted for clarity) (b) complete surface charge neutralization (c) in excess of surfactant, charge reversal by bilayer adsorption.

Let us redefine the problem. We start from the premises that the diffuse part of the double layer is fully relaxed but that the surfactant adsorption is not relaxed at all. In other words, the surfactant charge cr is fixed. We assume it to be negative, as in Fig. 1. Let us say that Na ions are the counterions in the Stem layer, and let their surface charge density in this layer be Then the question is what happens to the sum... 

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