Surfactants classification using

The 2000 report gives details of why changes in classification have been made and lists the new proposed classifications together with the old ones for comparison purposes. It notes that the recommended classifications apply only to individual surfactants. When used in preparations, some antagonism may occur and such situations must be dealt with on an individual basis. 

Classifications of the four types of surfactants have been proposed by various authors, and though the main organization remains more or less unchanged, changes are indeed visible in the literature on surfactant classification as a function of time as newer surfactants are synthesized and put to use [47, 1, 37, 3], As the area of application of surfactants discussed throughout this book is very specific and only selected surfactants are involved, we shall not go into the details of the classification here the reader is advised to consult specific sources [e.g. 1, 37, 3,47] if necessity arises. Only a skeletal classification, taken from Rosen [3], is given in Table 2.1 for an idea. Table 2.2 lists up some surfactants of different types that have been used in microemulsions and/or macroemulsions for the synthesis of particles. 

All the polymers used in polymer—surfactant interaction studies are water soluble. The interaction that they develop with one or more surfactants depends on the nature of both interacting partners. The macroscopic incidences of their interaction on liquid-phase properties are linked to concentration regimes at which associating polymers and surfactants are used. Therefore, Lindman and Thalberg [10] proposed a classification of polymer-surfactant interaction types according to the following ... 

There are a large number of emulsifiers of natural and synthetic origin, which fit into the surfactant classification given. The natural substances used as emulsifiers all fit into this system (See Table 4). 

Schemes for classifying surfactants are based upon physical properties or upon functionality. Charge is tire most prevalent physical property used in classifying surfactants. Surfactants are charged or uncharged, ionic or nonionic. Charged surfactants are furtlier classified as to whetlier tire amphipatliic portion is anionic, cationic or zwitterionic. Anotlier physical classification scheme is based upon overall size and molecular weight. Copolymeric nonionic surfactants may reach sizes corresponding to 10 000-20 000 Daltons. Physical state is anotlier important physical property, as surfactants may be obtained as crystalline solids, amoriDhous pastes or liquids under standard conditions. The number of tailgroups in a surfactant has recently become an important parameter. Many surfactants have eitlier one or two hydrocarbon tailgroups, and recent advances in surfactant science include even more complex assemblies [7, 8 and 9].

Although it is impossible to Hst all the practical detersive systems that might be encountered, a large proportion fall in a small number of classes. This classification disregards surfactant stmcture and type of substrate (fibrous or hard surface) and is restricted to a consideration of the soil present on the substrate, the mechanical action employed, the bath ratio, and the detergent used. Some of the more commonly encountered detersive systems are classified on this basis in Table 1. 

Alcohol sulfates are excellent foaming surfactants. According to the Kitchener and Cooper classification [148], alcohol sulfates form metastable foams. However, quantitative values cannot easily be compared because foam largely depends not only on the instrument used to produce and evaluate foam but also on the concentration of surfactant, impurities, temperature, and many other factors. In addition, a complete characterization of the foam capacity should take into account the initial amount of foam, its stability, and its texture. 

Amines are important industrial chemicals which are involved in everyday life [3, 4]. Apart from the usual classification into primary, secondary, and tertiary amines, the distinction is often made between lighf amines (less than six-carbon substituents) and fatty amines. light amines are intermediates for the synthesis of drugs, herbicides, cosmetics, etc. [3]. They also find use as vulcanization accelerators and extraction agents. Fatty amines are involved in the synthesis of corrosion inhibitors and cationic surfactants, which are used in ore flotation processes and are good fabric softeners and antistatic agents [4—6],... 

Particularly useful is the physical classification of surfactants based on the hydrophile-lipophile balance (HLB) system [67,68] established by Griffin [69,70]. More than 50 years ago he introduced an empirical scale of HLB values for a variety of nonionic surfactants. Griffin s original concept defined HLB as the percentage (by weight) of the hydrophile divided by 5 to yield more manageable values ... 

The surfactants used as textile auxiliaries can be divided into four major groups, depending on the type and distribution of the polar forces, an arrangement broadly resembling the ionic classification of dyes. The general scheme is shown in Table 8.1. 

Traditionally, the sol-gel process has been used for the preparation of silica nanoparticles via the hydrolysis of alkoxides in organic solvents [52,53]. Similar hydrolysis and condensation carried out in w/o microemulsion offers robust control over the synthesis process. W/o emiflsion-mediated sol-gel synthesis is currently used for the fabrication of pure sihca, as well as inorganic and organic dye-doped silica nanoparticles. The synthesis of sihca and dye-doped nanoparticles is classified in the following sections on the basis of the classification of the head group fimctionahty of the major surfactant used. 

There is some evidence to suggest that, depending upon the phase volume ratios employed, the emulsification technique used can be of greater importance in determining the final emulsion type than the H LB values of the surfactants themselves [434], As an empirical scale the HLB values are determined by a standardized test procedure. However, the HLB classification for oil phases in terms of the required HLB values is apparently greatly dependent on the emulsification conditions and process for some phase-volume ratios. When an emulsification procedure involves high shear, or when a 50/50 phase volume ratio is used, interpretations based on the classical HLB system appear to remain valid. However, at other phase-volume ratios and especially under low shear emulsification conditions, inverted, concentrated emulsions may form at unexpected HLB values [434]. This is illustrated in Figures 7.4 and 7.5. 

Many studies that have focused on the formation mechanism of various types of templated mesoporous materials have been summarized in a number of recent reviews,46 9 and it is still an ongoing topic of research.50 51 Here, we want to recapitulate only very briefly the useful interaction classification scheme between the surfactants (S) and the inorganic species (I), which was suggested by Huo et al.52,53... 

A simple classification of surfactants based on the nature of the hydrophilic group is commonly used. Four main classes may be distinguished, namely, anionic, cationic, zwitterionic, and nonionic. A useful technical reference is McCutchen. Another useful text, by van Oss et al., gives a list of the physicochemical properties of selected anionic, cationic, and nonionic surfactants. The handbook by Porter is also a useful book for classification of surfactants. Another important class of surfactants, which has attracted considerable attention in recent years, is the polymeric type. A brief description of the various classes is given below. 

An interesting sidelight of the organic structural classification study was that herbicidal activity could also be predicted 6). The nitrodiphenylethers could be divided into compounds which were strong herbicides and those compounds which showed little or no herbicidal activity. Both Faradaic and capacitive responses could be used to separate these classes for over half the experimental conditions examined. As was found in the classification of structure, capacitive factorial features performed somewhat better than Faradaic factorial features. It also appeared that classifications of herbicidal activity using Faradaic factorial features could be improved considerably by working at high pH and without surfactant present. The information content of Faradaic or capacitive variable effects data could be improved by variations in % ethanol. 

DOT CLASSIFICATION 8 Label Corrosive SAFETY PROFILE Moderately toxic by ingestion, skin contact, and subcutaneous routes. A corrosive irritant to eyes, skin, and mucous membranes. Dangerous fire hazard when exposed to heat, flames, oxidizers. To fight fire, use alcohol foam. When heated to decomposition it emits toxic fumes of NOx. Used as an intermediate in production of petroleum and polymer additives, and surfactants. See also AMINES. 

The octanol-water partition coefficient for surfactants can not be determined using the shake-flask or slow stirring method because of the formation of emulsions. In addition, the surfactant molecules will exist in the water phase almost exclusively as ions, whereas they will have to pair with a counter-ion in order to be dissolved in octanol. Therefore, experimental determination of K w does not characterize the partition of ionic surfactants (Tolls, 1998). On the other hand, it has been shown that the bioconcentration of anionic and non-ionic surfactants increases with increasing lipophilicity (Tolls, 1998). Tolls (1998) showed that for some surfactants, an estimated log Kow value using LOGKOW could represent the bioaccumulation potential however, for other surfactants some correction to the estimated log Kow value using the method of Roberts (1989) was required. These results illustrate that the quality of the relationship between log Kow estimates and bioconcentration depends on the class and specific type of surfactants involved. Therefore, the classification of the bioconcentration potential based on log Kow values should be used with caution. 

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