Surfactants secondary

Anionic surfactants are the most commonly used class of surfactant. Anionic surfactants include sulfates such as sodium alkylsulfate and the homologous ethoxylated versions and sulfonates, eg, sodium alkylglycerol ether sulfonate and sodium cocoyl isethionate. Nonionic surfactants are commonly used at low levels ( 1 2%) to reduce soap scum formation of the product, especially in hard water. These nonionic surfactants are usually ethoxylated fatty materials, such as H0CH2CH20(CH2CH20) R. These are commonly based on triglycerides or fatty alcohols. Amphoteric surfactants, such as cocamidopropyl betaine and cocoamphoacetate, are more recent surfactants in the bar soap area and are typically used at low levels (<2%) as secondary surfactants. These materials can have a dramatic impact on both the lathering and mildness of products (26). 

Competitor Brand Primary surfactants, 1984 Secondary surfactants, 1992... 

The secondary surfactant(s) in a detergent formulation. See also Detergent. 

Ci2 i4 olefin sulphonates are also used in personal care formulations since they are less aggressive than LAS and will not over-strip (i.e. degrease to leave an excessively dry or squeaky feel) the skin or hair although some care maybe required in formulating to compensate for a dry feel to the foam. AOS-based formulations are also more difficult to thicken than products based on alkyl sulphates or alkyl ether sulphates but use of alkanolamides or sarcosinates as secondary surfactants can overcome both problems and give a product more acceptable to the consumer. 

Products are normally supplied as a 30-40% solution, although products with a high level of sulphofatty acid will be viscous pastes at these concentrations, so secondary surfactants are often blended into such products to improve their storage and handling properties. 

Manual dishwash liquids are a major area of application. Whether the primary surfactant is LAS or SLS, ether sulphate is usually present as the secondary surfactant. The foaming generated by the ether sulphate is often the visual cue used by the consumer to judge the effectiveness of a product. This is reflected by the use of the loss of foam as the endpoint in many protocols used to evaluate dishwashing performance. 

Taurates can also be classed as modified soap, being similar to isethionates in structure and function. Taurates are useful secondary surfactants, used to modify the properties of primary surfactants. 

The wide availability of relatively inexpensive dimethylaminopropylamine (DMAPA) allows surfactant producers to convert economic triglycerides, fatty acids and methyl esters into amido -functional tertiary amines that may then be quaternized with sodium chloroacetate to produce alkylamidopropyl betaines (see Figure 6.15). The most economically significant of these is cocamidopropyl betaine which can be produced from a variety of feedstocks and lauramidopropyl betaine which is generally produced from lauric acid. These are widely used secondary surfactants in consumer products such as shampoos, bath products, washing up liquids and other cleaners. 

Usage of these products as secondary surfactants has greatly increased around the world as cocamide DEA (CDEA) fell into disfavor due to the propensity of free diethanolamine to... 

As the use of cocamidopropyl betaine increased as a secondary surfactant in anionic systems, the relatively low concentration of about 35% nonvolatiles at which it is normally sold became an issue. At this concentration, betaines are somewhat susceptible to bacterial growth so a preservative is often needed and the low concentration also increases freight costs so that several patented technologies were developed to address this [7]. Typically, the inclusion of about 2% of one of the patented additives allows the producers to prepare an aqueous solution of 45% nonvolatiles which is hostile to microbial growth without... 

Hydroxysultaines find use in personal care products, where they function as secondary surfactants to enhance the properties of anionic-based formulations, in much the same way as betaines. They are also among the best lime soap dispersants known, so they are used effectively in natural soap based products where they make the use of hard water practical. They are also used in petroleum production chemicals were they serve as foaming agents for acid and foam fracturing procedures. 

Here we use the term "multiple drop" to describe the oil droplets in w/o/w emulsions containing dispersed aqueous droplets, "primary" surfactant the stabilizer for the w/o emulsion and "secondary" surfactant to denote the more hydrophilic surfactant used to stabilize the o/w component. The "internal" phase is the dispersed aqueous phase, the "external" phase is the continuous aqueous phase and the "middle" phase the carrier oil droplets. 

Apart from the fact that the use of the HLB system is limited as it is based on the observation of creaming or separation of the emulsions, as an index of instability the HLB system also neglects the effects of surfactant concentration on stability (26) and of course it is irrelevant to the particular problems with multiple emulsion systems. Nevertheless, it provides a useful approach to the choice of optimal surfactant system. In general, in a w/o/w emulsion, the optimal HLB value of the primary surfactant will be in the range 2-7 and in the range 6-16 for the secondary surfactant. Equilibration of the systems after mixing will undoubtedly result in the transfer of surfactant between the aqueous and nonaqueous components. Saturation of the phases with the two surfactants used should prevent instability during this equilibration. 

Inversion of multiple w/o/w emulsions to o/w emulsions has been found to occur (28) only when the oil droplet size is reduced below a critical size or if the HLB of the emulsifiers approaches the required HLB of the oil phase. When these droplets were reduced in size below about 5 pm they no longer could accommodate an inner aqueous phase. Droplet size reduces with increasing concentrations of secondary surfactant (Fig. 2) which might, as Magdassi and co workers (28) point out, explain the results of Matsumoto et al (27). 

Figure It. The change in the optimal HLB of secondary surfactants used to prepare multiple v/o/v emulsions in which the primary w/o emulsion has heen stabilized "by 10% Bri,1 92. Reproduced with permission from Ref. 2EL Copyright 1979> J. Colloid Interface Sci.

Release of methotrexate, metoclopramide and sodium chloride from type A, B and C w/isopropyl myristate/w emulsions have been compared (Fig. 5 a,b,c). In all cases, release from the type C emulsion is not prolonged, which may be a reflection of stability or structure or a combination of these two parameters. In the case of methotrexate, variation of the concentration of secondary surfactant (polysorbate 80) from 0.5 to 20% had no significant effect on the rate of drug release from the system. 

Figure 3 illustrates the different steps of the process for the synthesis of these fluids. The result of Step A is a liophobic system obtained by chemisorption and this system is stable in non polar solvents but incompatible with aqueous solutions. To produce the water base ink, Step B is necessary where physical absorption of the secondary surfactant occurs on the hydrocarbon side of the chemisorbed oleic acid molecules creating a "double surfactant layer" around the particles. This model is in agjjgement with the one proposed by Rosenweigh and Shimoisaka. 

Secondary surfactants/foam boosters — nonionic and amphoteric 0-10... 

Secondary surfactants, which include nonionics, amphoterics, and some of the less widely used anionics, are often employed in a formulation to improve foam quality and stability, to provide additional detergency, and to enhance viscosity. Some of them are also used to reduce eye irritation in mild or baby shampoos. 

An important reason besides cleaning for using combinations of primary and secondary surfactants is to improve the quality and volume of foam. As discussed in Section II.A.2, some secondary surfactants such as betaines, amine oxides, and fatty alkanolamides also act as foam modifiers. They change the foams from a loose lacy structure generated by lauryl and laureth sulfates to rich and creamy foams. 

Generation of adequate lather is one of those product attributes that are crucial for a shampoo to be acceptable to consumers. Rich lathers can generally be attained through use of sufficiently high concentration of a primary, anionic surfactant together with a suitable secondary surfactant. 

Common secondary surfactants employed to boost or modify lather include cocamidopropyl betaine, cocamide DEA, cocamide MEA, and cocamidopropyl-amine oxide. Anionics, such as disodium lauryl and laureth sulfosuccinates are also employed in some products as foam boosters. 

Some ingredients in shampoos, notably dimethicone, can depress lather. The presence of these materials must be compensated for, by increasing surfactant concentration, changing the secondary surfactant, or adding additional foam boosters such as cetyl alcohol. 

For simple cleaning shampoos, adequate rheological properties can generally be obtained by the same methods used for lather sufficiently high primary surfactant plus the same secondary surfactants listed above as lather modifiers. 

Fatty acid alkanolamides are widely known as a secondary surfactant, namely as foam and detergency booster, co-emulsifier, viscosity modifier, hair and skin conditioner, corrosion inhibitor, and moderate antistatic [2, 22]. Some trade names of alkanolamides are as follows (I) Amidet A-lll Kao), Comperlan 100/LM Henkel), Empilan CME Albright Wilson), Lauridit KM Akzo Nobel), Monamid MEA Uniqema), Rewomid C/L/S/U Witco) (II) Empilan CIS/LIS Albright Wilson), Ninol M-10 Stepan), Rewomid IPE/IPL/IPP and Witcamide SPA (all of Witco)-, (III) Alkamide KD Rhodia), Aminol KDE Kao), Comperlan COD/KD/LD/ODA OD and Texamin PDl (all of Henkel), Empilan CDE/CDX/ 2502/LDE Albright Wilson), Lauridit KDG Akzo Nobel), Mackamide CS/LLM McIntyre)-, Purton CFD/SFD Zschimmer Schwarz), "Rewomid DC/ DO/F", "Rewocid DU 185 SE" and "Witcamide LDT/S" (all of Witco)-, (IV) Aminol A15 Kao). 

Condensation products of fatty acid halides and protein hydrolysates are produced now in a wide range as secondary surfactants for the same needs. They may be modified additionally by quatemisation to gain more cationic nature as mentioned in the previous paragraph. The number of amino acids attached varies over a wide range whereas their morphological state... 

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