Amphiphile/amphiphilic Amphoteric

EYP have been chosen as the emulsifier in all second generation PFC emulsions. EYP, whose major constituents are the amphiphilic amphoteric phosphatidylcholines 13, provide significantly better emulsion stability than poloxamers. The stabilization effect is particularly remarkable with Emulsions... 

Amphiphile-oil-water system, temperature of, 16 424-426 Amphiphiles, 16 420 Amphiphile strength, 6 424 Amphiphilic chemicals, 17 56 Amphiphilic copolymers, 20 482 behavior of, 20 483 well-defined, 20 485-490 Amphiphilic molecules, 15 99-101 Amphiphilic plasticizers, 14 480 Amphiphilic polymer blend, 23 720 Amphiphilic polymers statistical, 20 484-490 stimuli-responsive, 20 482-483 Ampholytes, 9 746-747 Amphoteric cyclocopolymers, water-soluble, 23 721 Amphoteric starches, 4 722 Amphoteric (zwitterionic) surfactants, 24 148... 

Amphiphilic compounds as surfactants, 21 Amphoteric surfactant, definition, 386 Analysis speed, importance, 125 Anionic surfactants definition, 387... 

For the present system, we demonstrate the amphiphilic character of the complexed polyelectrolyte to override its amphoteric characteristics. There-... 

The size and shape of micelles are determined by a delicate balance between various factors, such as chemical constitution, electrical repulsion of head groups, amphiphile and solute concentration, and temperature. The addition of electrolytes will in general raise aggregation numbers of ionic micelles and may even induce sphere-rod transitions. Temperature has an enormous influence on aggregation numbers of nonionic micelles, but only a little effect on those of ionic and amphoteric micelles. There is a vast literature covering the subject (24,25,36). 

Surface active substances or surfactants are amphiphilic compounds having a lyophilic, in particular hydrophilic, part (polar group) and a lyophobic, in particular hydrophobic, part (often hydrocarbon chain). The amphiphilic structure of surfactants is responsible for their tendency to concentrate at interfaces and to aggregate in solutions into various supramolecular structures, such as micelles and bilayers. According to the nature of the polar group, surfactants can be classified into nonionics and ionic, which may be of anionic, cationic, and amphoteric or zwitterionic nature. 

An amphiphilic compound is named amphoteric surfactant if its functional group is capable of carrying both anionic and cationic charges. The term amphoteric surfactants or... 

At least two of the recognized mechanisms for the formation of electrical double layers (Hunter, elal. 1981 Russel etal., 1989) are relevant to LB film depositions (1) ionization of carboxylic acid group and amphoteric acid groups on solid surfaces, and (2) differences between the affinities of two phases for ions or ionizable species. The latter mechanism includes the uneven distribution of anions and cations between two immiscible phases, the differential adsorption of ions from an electrolyte solution to a solid surface, and the differential solution of one ion over the other from a crystal lattice. Since the solid-liquid and the film-liquid interfaces are flat, large surfaces and since both have a large, solid-like concentration, the analysis that follows applies to both interfaces. For an interface conformed by a thin film of an amphiphilic compound with the hydrophilic end of the molecule in contact with the water subphase, the equilibrium of charges is based on pH and subphase concentration. The effect of pH is highlighted by the definition of the of the carboxylic acid ... 

The majority of surfactants used in coatings formulations are standard anionic and nonionic amphiphiles, such as fatty alcohol sulfates, alkylaryl sulfonates and alcohol ethoxylates. Cationic and amphoteric surfactants... 

Proteins are the most abundantly occurring natural polyampholytes. In addition to their amphoteric character, proteins are amphiphilic heteropolymers. The distribution of the monomers (the various amino acid residues) determines the amphiphi-licity and charge distribution and is therefore largely responsible for the 3D structure of a protein molecule in aqueous solution. Principles governing the protein structure and structural stability are treated in more detail in Chapter 13. 

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