Amine Based Surfactants

Transmission electron microscopy (TEM) has been an underutilized yet valuable too in particle size characterization of MC particles in LB films. Monolayer films of trioctylphosphine oxide-capped CdSe (18), spread as a monolayer on an aqueous subphase, were transferred to a TEM grid. A close-packed hexagonal arrangement of 5.3-nm (cr —4%) crystallites was found. TEM images were also obtained for HMP-stabilized CdS incorporated in BeH/octadecylamine films (79) and for CdS formed under an amine-based surfactant monolayer and transferred to a TEM grid (14). In one study, direct viewing of CdS and CdSe particles made from Cd2+-FA films on TEM grids was not possible due to poor phase contrast between the particles and the film (30). Diffraction patterns were observed, however, that were consistent with crystalline (3-CdS or CdSe. Approximately spherical particles of CdSe could... 

Cationic surfactants represent one of the smaller classes of surfactants, with a consumption estimated to be 700000 tons per year. Typically, reviews and market studies include in this class of materials all amine-based surfactants, whether they be charged or uncharged. In this present chapter we will use the same definition, but exclude amphoteric materials, which will be covered in the next chapter in this volume. 

Another important class of cationic surfactants are the polyamine-based or polyquatemaries. Generally, the synthesis of the poly amine-based surfactants is similar to that for the monomeric counterparts, and will not be discussed any further here. 

Franklin, F., et al., Cationic and amine-based surfactants, in Oleochemical Manufacture and Applications, Gunstone, F.D., Hamilton, R.J. (eds), chap. 2, CRC Press, Boca Raton, FL, 2001. 

LONZA INC. Amine Based Surfactants (Continued) AMPH0TER6E ... 

As a result, various non-amine-based products have been introduced to the market that continue to provide appropriate levels of corrosion protection, yet do not exhibit the limitations normally associated with amines. The most promising of these are the sorbitan-based, nonionic surfactant treatments, such as those marketed by ONDEO Nalco under the Tri-Act brand (U.S. patent 5,849,220, December 1998). 

PVP, a water soluble amine-based pol5mer, was found to be an optimum protective agent because the reduction of noble metal salts by polyols in the presence of other surfactants often resulted in non-homogenous colloidal dispersions. PVP was the first material to be used for generating silver and silver-palladium stabilized particles by the polyol method [231-233]. By reducing the precur-sor/PVP ratio, it is even possible to reduce the size of the metal particles to few nanometers. These colloidal particles are isolable but surface contaminations are easily recognized because samples washed with the solvent and dried in the air are subsquently not any more pyrophoric [231,234 236]. 

The alkyliminodipropionates described above are somewhat more expensive than most other hydrocarbon-based surfactants. This is due to the cost of the alkyl primary amines used to produce them relative to other available fatty acid amide based amines. 

Micro-emulsions, as noted originally by Schulman in 1943, are transparent, seemingly homogeneous solutions of water, oil, surfactant, and an alcohol- or amine-based co-surfactant. These isotropic dispersions of two immiscible liquids such as oil and water are stabilized by the presence of emulsifier(s) (surfactant molecules that can be cationic, anionic, or neutral), which are located at the interfaces between oil and water domains. The most common examples are the water-in-oil (W/O) and the oil-in-water (OfW) micro-emulsions. The use of micro-emulsions in the synthesis of materials allows size-selective growth of small particles in water droplets homogeneously entrapped in a hydrocarbon solvent. The important properties are governed mainly by the water-to-surfactant molar ratio. 

In addition, in many industrial practices, additional carbon dioxide or freon gas (a major sources of environmental pollution) may be introduced into the system as it cures. For rigid foams a low boiling liquid may be added to form additional bubbles. Appropriate catalysts and foam stabilizers or surfactants are added to control foam formation, cell size, and cure. The catalysts are either tin compounds or tertiary amines. The surfactants that are necessary to control the cell size are usually based on siloxanes. 

With the aim of designing a biologically inspired carrier in which the encapsulation and the delivery of DNA can be efficiently controlled, Amar-Yuli et al. have designed two lipid-based columnar hexagonal LLCs [58], which can accomplish two opposite roles while maintaining the same liquid crystalline symmetry. The first system was based on a nonionic lipid, such as monoolein, while the second system was modified by a low additional amount of the oleyl amine cationic surfactant. DNA was enzymatically treated to generate a broad distribution of contour lengths and diffusion characteristic times [58]. 

An amphoteric amine sulfate surfactant is tested as a catalytic system for the base-catalyzed hydrolysis of a triglyceride. What pH range (<5, 5-8, <8) would you expect to be most appropriate for maximum rate enhancement Explain why. 

There are various synthetic routes to introduce hydrocarbon long chains into amino acid-based surfactants. For example, a long-chain fatty acyl group is introduced on the amino part of amino acids by using an acid chloride. To obtain amino acid esters or amides, the carbonyl parts of amino acids are reacted with fatty alcohol or amines, respectively. For example, C-alkylation of an amino acid is obtained by the reaction of a-bromo fatty acid with ammonia or by a transmission reaction of the amino part of the amino ester with a stable Schiff base followed by deprotonation with a strong base. This is followed by alkylation with an alkyl halide. N-Alkylation of an amino acid is generally obtained by the reaction of fatty amines with monochloroacetic acid, methyl acrylate, or maleic acid or by the addition of 1,2-epoxy alkane to amino acids. 

A systematic investigation into structure-property relationship of novel long-chain A -alkylamide series 2 and O-alkyl ester series 3 arginine-based surfactants (Scheme 1) was carried out [25]. Compared to series 1, the new series 2 and 3 (Scheme 1) have two positively charged groups in the hydrophilic moiety, one in the primary amine and a second in the guanidine function. 

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