Surfactants polyoxyethylene sorbitan fatty acid

Non-silicone oUs are nonionic surfactants, which are polymers of castor oil, lanolinic acid and various kinds of alkylene oxide. These products are made by Daiichi Kogyo Seiyaku, Ltd. and are sold on the market under the trade names of Resinol F-140 and F-520 (6). Polyoxyethylene sorbitan fatty acid ester, such as the Tween series (Atlas Chemical Industries), can also be used. 

Surfactants are used to control cell size and structure. The most common surfactants are siloxane-oxyalkylene copolymers, polyoxyethylene sorbitan fatty acid esters, and the condensation products of ethylene oxide with castor oil and alkyl phenols. A commonly added additive is urea which is used as a formaldehyde scavenger. Very fine particle size inorganic fillers can be added to act as nucleating sites and to promote finer, more uniform cell structure, as well as increased compressive strength, but at a cost of higher density. 

Ethoxylated Anhydrosorbitol Esters. Ethoxylation of sorbitan fatty acid esters leads to a series of more hydrophilic surfactants (Table 19). All hydroxyl groups of sorbitan can react with ethylene oxide. The stmcture of the principal component of a nominal polyoxyethylene (20) sorbitan monostearate illustrates the composition of these products, where w x y z = 20. 

Several non-ionic surface-active materials have been developed as suppositories vehicles. Many of these bases, known as water-dispersible bases, can be used for the formulation of both water-soluble and oil-soluble drugs. The surfactants most commonly used are thepolyoxyethylene sorbitan fatty acid esters (Tweens), the polyoxyethylene stearates, and the sorbitan fatty acidesters (Spans). These surfactants may be used alone, blended, or with other suppository base materials to yield a wide range of melting points and consistencies. 

A wide variety of this group of surfactants is commercially available. They include some of the Tritons (alkyl phenol additives, as far as they are non-ionic). Tweens (sorbitan fatty acid ester polyoxyethylene ethers). Spans (sorbitan fatty acid esters) and alkyl polyoxyethylenes (C Ej, where n and x stand for the number of CH2- or CH3-. and CHjO-groups in the hydrophobic and hydrophilic parts of the molecule, respectively). Given our interest in the fundamentals we shall emphasize only the last-mentioned group, and only when n and x are sharply defined emd the two moieties are either linear or branched in a defined way. Unless specified otherwise, there is an OH-group at the end of the E-chain. Notwithstanding the non-ionic nature of these molecules, micelles sometimes appear to cany a (low) charge probably caused by preferential uptake of ionic species. 

Table 6.11 Relation between HLB of polyoxyethylene glycol stearates and polyoxyethylene glycol sorbitan fatty acid esters and the minimum bactericidal concentration of tyrothricin. Surfactant concentration 2x lO- moir ...

Vineland, NJ) or over-the-counter cosmetic creams promoted for improved hydration (L Oreal, Paris and Dior, Paris). More recently, parenteral liposome formulations of amphotericin B, doxorubicin, and dau-norubicin have been approved and marketed (ABELCET, Elan, the Liposome Co., Inc, Princeton, NJ AmBisome and DaunoXome, Nexstar/Fujisawa, Deerfield Park, IL Amphotec and Doxil, Sequus/ Alza, Menlo Park, CA), with others on the horizon for applications in photodynamic therapy. Although the vast majority of liposome preparations are constructed from phospholipids, other nonphospholipid materials can be used either alone or in mixtures to form bilayer arrays. One such example is Amphotec, which utilizes sodium cholesteryl sulfate as the primary lipid. Other liposome forming materials may include but are not limited to fatty-acid compositions, ionized fatty acids, or fatty acyl amino acids, longchain fatty alcohols plus surfactants, ionized lysophospholipids or combinations, non-ionic or ionic surfactants and amphiphiles, alkyl maltosides, a-tocopherol esters, cholesterol esters, polyoxyethylene alkyl ethers, sorbitan alkyl esters, and polymerized phospholipid compositions. ° ... 

In practice, two types of emulsifiers are used (1) ABA triblock copolymers (e.g., Hypermer B246, HLB = 6 and B261, HLB = 8, IQ), where A is a polyester derived from 12-hydiostearic acid and B is a polyoxyethylene and (2) nonionic emulsifiers such as fatty acid esters of sorbitan and polyoxyethylene derivatives. Note also that the amount of surfactant is higher than that employed in conventional emulsion polymerization, in connection with the stability problems discussed above it lies within 2-5 wt% of the total mass. 

Surfactants (surface active agents) are very important constituents of many industrial formulations. In these formulations, it is often not just one compound that is of interest. Rather, the overall identity, as determined by the presence and distribution of the individual components, is critical. Kondoh et al. [224] developed a method for determining non-ionic surfactants containing ester groups, such as sorbitan and sucrose fatty acid esters and polyoxyethylene fatty acid esters, as their o-nitro-phenylhydrazine derivatives. To remove the residual free fatty acid fraction, 6 mM triethylamine (TEA) was added to the 85/15 methanol/water starting mobile phase. The free fatty acids then eluted in the void volume and the separation of the analytes of interest was conducted on a C]g column (A = 550 nm). Elution and identification up to the penta-ester resulted when a 50-min 0/85/1575/25/0 ethanol/ methanol/water (6 mM TEA) gradient was used. 

One area of rapidly expanding interest is the use of reverse micellar systems of sugar-based surfactants in the extraction of proteins and other sensitive materials. The use of hydrophilic, nonionic, sugar-based surfactants for membrane protein extraction is well known to be effective due to the mild, nondenaturing properties of these surfactants when compared with ionic surfactants or polyoxyethylene derivatives. For the same reasons, protein extraction into reverse micellar systems is now becoming a popular medium for such applications. Alkyl sorbitan esters and ethoxylated sorbitan esters, such as Tween 85 [107] and Span 60 [108], have been used successfully to form reverse micellar systems for protein extraction. Blends of Tween and Span have also been found to be effective for this purpose [109]. More recently, commercially available sucrose fatty acid esters have been shown to form biocompatible reverse micellar systems into which cytochrome c is effectively extracted [110]. 

For shaving products, creams, foams, lotions, etc. are commonly used. The most frequently used ingredients in shaving products are fatty acids (e.g. stearic acid), surfactants (e.g. triethanolamine), emulsifiers (e.g. lanolin, polyoxyethylene sorbitan monostearate), solvents and emollients (e.g. glycerin and other alcohols). 

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