Surfactant-like anions

More recently, it has been found that anions such as polyelectrolytes and surfactant-like anions, for example, dodecylbenzenesulfonate (DBSA), can be inserted directly into PPy products during polymerization in competition with anions arising from the oxidant. This very useful development will be discussed later in a section dealing with PPy processability. 

Three generations of latices as characterized by the type of surfactant used in manufacture have been defined (53). The first generation includes latices made with conventional (/) anionic surfactants like fatty acid soaps, alkyl carboxylates, alkyl sulfates, and alkyl sulfonates (54) (2) nonionic surfactants like poly(ethylene oxide) or poly(vinyl alcohol) used to improve freeze—thaw and shear stabiUty and (J) cationic surfactants like amines, nitriles, and other nitrogen bases, rarely used because of incompatibiUty problems. Portiand cement latex modifiers are one example where cationic surfactants are used. Anionic surfactants yield smaller particles than nonionic surfactants (55). Often a combination of anionic surfactants or anionic and nonionic surfactants are used to provide improved stabiUty. The stabilizing abiUty of anionic fatty acid soaps diminishes at lower pH as the soaps revert to their acids. First-generation latices also suffer from the presence of soap on the polymer particles at the end of the polymerization. Steam and vacuum stripping methods are often used to remove the soap and unreacted monomer from the final product (56). 

Higher molecular primary unbranched or low-branched alcohols are used not only for the synthesis of nonionic but also of anionic surfactants, like fatty alcohol sulfates or ether sulfates. These alcohols are produced by catalytic high-pressure hydrogenation of the methyl esters of fatty acids, obtained by a transesterification reaction of fats or fatty oils with methanol or by different procedures, like hydroformylation or the Alfol process, starting from petroleum chemical raw materials. 

Ethylene oxide is an important intermediate chemical not only for the production of nonionic surfactants like fatty alcohol ethoxylates, alkylphenol ethoxy lates, or propylene oxide/ethylene oxide block copolymers, but also for manufacturing of anionic surfactants like alcohol ether sulfates. 

Anionic surfactants like alkanesulfonates can also be determined by poten-tiometric titration with ion-selective electrodes. Recently, a special PVC electrode was offered as a high-sense surfactant electrode in combination with the new titrant l,3-didecyl-2-methylimidazolium chloride [20]. This one-phase... 

Ammonium salts of alkenyl succinic half-amides have teen described for use as corrosion inhibitors in oil and gas production technology to combat corrosion by media containing CO2, H2S, and elemental sulfur [1366]. The inhibitor composition may contain a dispersing agent, such as a low molecular weight or polymeric anionic surfactant like an alkylsulfonic acid or an alkyl-aryl sulfonic acid. 

Recently, a series of surfactant-like peptides were found to form helical nanotubes.112 The anionic peptide monomers were composed of a head group of one or two aspartic acids and a hydrophobic tail containing six residues... 

Do not use PVP with anionic surfactants like linear alky lbenzene sulfonate, since it is susceptible to deactivation by those surfactants. 

Do not use enzymes in formulations containing cationic surfactants, anionic surfactants like alkylbenzene sulfonates, and bleaches like hypochlorite and percarboxy lie acids, since they can degrade enzymes. 

Cationic Surfactants. Like the anionic surfactants, cationic surfactants also dissociate in an aqueous medium. However, the head (hydrophilic portion) is a cation, which is the carrier of the surface-active properties. Examples are the quaternary ammonium compounds. 

A characteristic feature of the parent polypyrroles, polythiophenes and polyanilines is their insolubility in water and common organic solvents (although the EB form of polyaniline is soluble in NMP, DMSO and several other solvents). This intractability and consequent difficulties in processing have until recently limited their exploitation. However, the introduction of substituents onto the aromatic rings of the polymers, the use of surfactant-like dopant anions and the generation of colloidal dispersions have markedly enhanced the processability of ICPs (see Section 8 below). 

For organic solvent solubility, an alternative approach to solubilising polyanilines and polypyrroles, without sacrificing high electrical conductivity, is the use of surfactant-like dopant anions. With polypyrrole this has recently been achieved via oxidation of the pyrrole monomer with ammonium persulfate in the presence of dodecylbenzene sulfonate [128,129]. Similarly, the conducting emeraldine salt form of PAn.HA can be readily solubilised in a range of organic solvents via the use of camphorsulfonic acid or dodecylbenzenesulfonic acid as the dopant, HA [130,131]. 

An important breakthrough in PPy chemistry was the discovery by Lee and coworkers95 in 1995 of a chemical polymerization route to an unsubstituted PPy that was soluble in organic solvents. They exploited the surfactant-like qualities of added dodecylbenzenesulfonate (DBSA 9) as a dopant anion to solubilize PPy formed during oxidation of pyrrole by aqueous (Nn4)2S208. The PPy/DBSA product, isolated as a black powder in 42% yield after 40 h reaction at 0°C, was very soluble in m-cresol, and could be dissolved in weakly polar solvents such as chloroform and dichloro-methane by the addition of an equimolar amount of dodecylbenzenesulfonic acid. A film cast from chloroform solution exhibited an electrical conductivity of 5 S cm-1, and its UV-visible spectrum was similar to that of electrochemically deposited PPy. 

Like anionic surfactants, cationics can also be determined by formation of ion pairs with colored water-soluble anionic species, extractable into chloroform only in the presence of cationic surfactants. One of the most widely used methods is based on disulfine blue [40]. The absorbance of chloroform extract containing cationic surfactant - disulfine blue complex is measured at 628 nm against chloroform background. Picric acid and sodium p-(2-hydroxy-... 

At the same time, surfactants like alkylbenzene sulfonates remain the most widely used basis for laundry detergents. Anionics remain the main products for making detergent compositions. Some of the application aspects of relatively new types of anionics (a-olefin sulfonates, sulfocarboxylic acids, alkyl phosphates etc.), whose commercial manufacture began in the 60-ties - 70-ties of the 20 century, are described by Stache [95]. The application of conventional types of nonionics like ethoxylated alcohols or alkyl phenols is presented in [13 -14], Alkyl polyglycosides were widely used in the last 5-8 years [96]. However, the main tendency in the development of new generation detergents is the use of surfactant mixtures in their optimum composition [97, 98]. 

Robbins et al. [29] have shown that washing monofunctional cationic surfactants like cetrimonium chloride from hair with normal alkyl sulfates or alcohol ether sulfates does not remove all the cationic from the hair, and, in addition, the anionic detergent can build up with the cationic. Adsorption complexes formed in this manner adsorb to hair with the potential for building up. However, this type of buildup generally levels after five to six treatments. Shorter chain-length surfactants like deceth-2 or -3 ether sulfate do not build up in the same manner. In addition, hair matting has been reported in vivo and attributed to the adsorption of cetrimonium bromide on hair [42]. 

Sykes and Hammes [43] have described the adsorption of both of these cationic polymers onto hair from solutions of different amphoteric and anionic surfactants. Analogous to the adsorption of polymer JR, uptake values were greater onto bleached hair than onto unbleached hair, and greater from amphoteric systems like cocobetaine or cocoamphyglycinate than from anionic surfactants like sodium lauryl sulfate or triethanolam-monium lauryl sulfate. 

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