Personal care formulation

Fatty acid and unsaturated fatty acid mono- and diethanolamides Fatty acid mono- (FAMA) and diethanol amides (FADA) with the general formula (C,32n+1-C(0)N(HyCH2-CH2-0H)2 x = l or 0) are presented with their general structural formulae in Fig. 2.9.28(a) and (b). These surfactants have found a widespread application in household and personal care formulations because of their quite good... 

Yet another use of surfactants with limited stability is to have the cleavage product impart a new function. For instance, a surfactant used in personal care formulations may decompose on apphcation to form products beneficial to the skin. Surfactants that impart a new function after cleavage are sometimes referred to as functional surfactants. 

The most common and best known chelant is ethylenediaminetetraacetic acid (EDTA). The related compounds diethylenetriaminepentaacetic acid (DTPA) and nitrilotriacetic acid (NTA) are also well known (Figure 10.2). EDTA is a powerful chelant that complexes strongly with most metal ions to form six-coordinate complexes. It has therefore become the first choice in most applications. Indeed, a search of the bathroom cabinet will spot EDTA on the ingredient list of many personal care formulations. DTPA is also a powerful chelant, but tends to be used more often in industrial settings. NTA has only four binding sites and is used more often where hardness ions require control, such as in cleaning, for example, hard surface cleaners, dishwashing, and the dairy industry. 

Specific by-products in some surfactants may give rise to concern on toxicological grounds and permitted by-product levels and/or use of levels of that surfactant maybe restricted in particular formulations, e.g. nitrosamine levels in diethanolamides when used in personal care formulations. 

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. 

Sulphosuccinates are not particularly effective detergents but they are good wetting agents and the monoesters are favoured in personal care formulations because of their very low irritancy. 

Ether carboxylates are a very versatile class of surfactants, used in diverse applications from mild personal care formulations to lubricants and cutting fluids. They are interrupted soaps, with the addition of a number of ethylene oxide groups between the alkyl chain and the carboxylate group. The additional solubility imparted by the EO groups gives much greater resistance to hardness and reduced irritancy compared to soap. 

Gum, M.L. (1985) Water-in-volatile silicone emulsifier concentrates for mixing with water to form water-in-volatile silicone emulsions that are useful in personal-care formulations and methods of making same. PCT Int. Appl. 8503641. (Union Carbide Corp., USA Application WO). WO. p. 56 pp. 

Ag uat [CPS] Pdyquateroium cationic polymers for personal care formulates, as drainage and retention... 

Phase diagrams are not only a useful tool they are a ne-eessity in other faeets of emulsion applieations fliis is the ease when flie applieation involves evaporation (personal-care formulations, pharmaceuties) or dilution (agrieultural emulsions, foods). Some eomplex model systems will be discussed in the sections designated to these areas in this introduction only the phase ehanges in a simple two-phase emulsion (5) will be reviewed to illustrate this point. 

Uses Detoamer tor water-based paper coatings, textile processing formulations, agric. chemical prods., paints, adhesives, inks, and personal care formulations Bubblekup [Malvern Mins.)... 

Chem. Descrip. Nonoxynol-4 CAS 9016-45-9 EINECS/ELINCS 230-770-5 Uses Detergent, emulsifier, defoamer for pesticide, paint, paper, and textile industries, and personal care formulations Properties Liq. oil-sol. HLB 8.8 nonionic 100% act. 

Chem. Desaip. 58-62% Polyethoxy methacrylate, 18-22% methacrylic acid, 18-22% water, 150-250 ppm MEHQ Uses Monomer for use in alkali-sol. associative thickeners used in architectural coatings, paper formulations, personal care formulations, adhesives, grouts and cements... 

Uses Emulsifier for polymerization, personal care formulations... 

Uses Emulsifier in cosmetics emollient, humectant, pigment, conditioner, lubricant for personal care formulations solubilizer superfatting agent for cleansing prods. 

In a side reaction, the sodium chloroacetate or chloroacetic acid is hydrolysed to glycolic acid this side reaction is controlled by the pH of the reaction mixture. The glycolic acid content usually is below 0.1% but may be as high as 1%. There is little concern about the glycolic acid, as it is often added to personal care formulations. 

A secondary surfactants group with increasing economical importance are the A -(2-aminoethyl)-2-aminoethanol (aminoethylethanolamine)-derived amphoterics. Because the intermediate in the synthesis of these surfactants is a substituted imidazoline, they are also classified as being imidazoline-derived. Historically, these mild surfactants have been the first to offer the possibility for the production of non-eye-stinging shampoos. Still today, aminoethylethanolamine-derived amphoterics are mainly used in personal care formulations where mild properties are desired, whereas industrial applications play only a minor role. 

In particular, two groups of aminoethylethanolamine-derived amphoterics have found use in personal care formulations, i.e. the amphomonoacetates and amphodi-acetates. The key structures of these mono- and dicar-boxy lie derivatives are given in Figure 15.14. 

Ansmann A, P Busch, H Hensen, K Hill, HU Krachter, and M Muller, Personal care formulations. In Handbook of Detergents, Surfactant Science Series, Vol. 128 (Ed. Zoller U), Taylor Francis, 2006, pp. 207-260. 

When polymers are employed in personal care formulations, in many (if not most) cases they occur as cocomponents with surfactants. Recognizing a widespread tendency of such components to interact and affect each other s properties (sometimes in dramatic ways). Chapter 4 outlines a number of methods to investigate and analyze snch interaction for the main types of polymers—nonionic, ionic, hydrophobic, and proteinaceons. Chapter 5 presents an illustrative selection of polymer/surfactant interactions in applied systems that demonstrates how they can be selected to achieve beneficial performance effects. 

Synthetic polymers are ubiquitous in the personal care industry. Chapter 6 strives to address this rather broad topic in a straightforward and easily readable fashion. The chapter starts with a brief discussion of how synthetic polymers are made and the nomenclature used to describe some of the more basic structural principles of synthetic polymers. It expands to address many of the synthetic polymers used in personal care formulations based principally on their primary mode of operation, including thickening polymers, fixative polymers, conditioning polymers, and encapsulating polymers, the last subject becoming more important as formulators develop more sophisticated topical systems to deliver active materials. 

The above method of stabilization (referred to as electrostatic stabilization) can be produced by the use of ionic surfactants (of the anionic, cationic, or zwitterionic type). However, for a number of reasons this method of stabilization is not ideal for personal care formulations. First, the stabilization is influenced by the presence of electrolytes in the system, which reduces repulsion and may cause instability. In addition, many ionic surfactants cause skin irritation as a result of their penetration and interaction with the stratum corneum (4). The latter is the main barrier to water loss and it consists of lipids that are organized in a bilayer structure (liquid crystalline), which at high water content is transparent and soft (5). Surfactants that interact with the lipid bilayer and reduce its liquid-like nature (by disrupting the liquid crystalline structure) may cause crystallization of the lipids, and this has a drastic effect on the appearance and smoothness of the skin ( dry skin feeling). 

This chapter will begin by examining briefly the monomer building blocks of many of the key synthetic polymers used in the personal care industry. Chapter 1 addresses, in a more formal and fundamental fashion, the basic elements of polymer science. The functional properties of the synthetic polymers are dictated, in part, by the monomers from which the polymers are comprised. In addition, the architectural arrangement of the monomers will be critical to understanding the functional roles the polymers play in the personal care formulations. 

Surfactants are ubiquitous in industrial applications. Especially in the coatings (i.e., paint) and personal care industries, surfactants play a significant role. These industries share many common concerns since cosmetics are largely coating systems. Often, useful ingredients in coatings applications find their way into personal care formulations. Naturally, the safety considerations are compounded and stricter in the latter application. 

In more concentrated surfactant solutions where rod-like and branched mieelles exist, theoretical descriptions of these associative thickeners are lacking. What is clearly understood is that the nature of the surfactants profoundly influences the rheology of personal care formulations (105-107). Factors that influence the electrical environment of the formulation, such as salt and pH, also affect the behavior of these thickeners. Unfortunately, the lack of understanding typically means that formulators must use trial and error to develop stable formulations. 

Aminosilanes of the general formula R Si(NH2)4- , R Si(NHR)4 , R Si(NR2)4- are prepared by the reaction of silicon hydrides or chlorosilanes with ammonia or other amines in the presence of an inert solvent. These hydrosilylation reactions may be carried out at room temperature, with the reaction products being isolated by simple phase separation (3,46-48). To obtain the MD D M type aminofunctional siloxanes typically employed in personal care formulations, aminofunctional silanes (generally aminoethylaminopropyltri-methoxysilane or y-aminopropyltrimethoxysilane) may be polymerized with linear hydrolysates or with octamethylcyclotetrasiloxane to form aminofunctional silicone fluids. Nucleophilic substitution and redistribution reactions have also been used to prepare one modified silicone from another. For example, aminofunctional siloxanes may be prepared by substitution as illustrated in Eq. (4). 

While alkyl modified silicone (AMS) polymers have been known for many years, primarily as metal or textile lubricants, it is only within the past several years that these materials have become desirous in personal care formulations. The reason for this is that in the past, the alkyl groups grafted onto the silicone polymers were long-chain linear moieties resulting in very hard, brittle waxes that were difficult to work with and did not offer significant advantages over organic materials in personal care products. With introduction of branched alkyl moieties into the silicone polymers, the molecular symmetry is disrupted. 

In addition to the commonly encountered silicone compounds listed above, a number of other specialized silicone derivatives may be found in personal care formulations. These substances include siliconized natural waxes, fragrances, sunscreens, pigments, amino acids, minerals, vitamins, botanical extracts, essential oils, fatty acids, fatty alcohols, and the like. The various types of compounds that have been covalently bonded onto silicone polymers are quite extensive and will not be discussed in further detail in this chapter. 

Approximately 13%, or 20,000 metric tons, of volatile polydimethylsiloxanes are used in personal care formulations, of which 92% (mainly D4 and D5) partitions to the air (186). Because of their extremely low water solubility, high vapor pressure (see Table 7), and high Henry s law constant (>3), these materials are not found to any appreciable extent in soil or water. Indeed, the aquatic volatilization rate (the rate at which a compound migrates from water to air) of D4 has been found to be 0.57, corresponding to a half-life... 

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