Nonionic Surfactants

Nonionic surfactants do not dissociate into ions in aqueous medium. They generally deliver a weak to moderate foam. They are appreciated for their good skin and eye compatibility as well as for their anti-irritant potential when they are combined with anionics in appropriate concentration ratio. Therefore, numerous products for sensitive skin, babies, or the face incorporate nonionics as major surfactants.

Fatty Alcohols |>

Fatty alcohols are primarily used as a chemical precursor for the production of several other surfactants.

Fatty alcohol @

Because they are not water soluble, the use of fatty alcohols is very limited in liquid products. They are mainly used as opacifiers, thickening agents, and foam depressors (e.g., lauric alcohol).

Ethers

Alkoxylated Alcohols

This class of surfactants mainly covers ethoxylated or propoxylated alcohols. Ethoxylated alcohols (also called ''polyethyleneglycol ethers'' or ''PEG ethers'') are produced from the reaction of fatty alcohols with ethylene oxide (EO). Similarly, propoxylated alcohols (also called ''polypropyleneglycol ethers'' or ''PPG ethers'') are obtained with propylene oxide (PO). The HLB of ethoxylated alcohols can be adjusted by properly balancing the hydrophilic ethoxylated chain and the hydrophobic fatty chain. Ethoxylate nonionics are compatible with all surfactants. Some beneficial associations with ionic surfactants are often shown.

In the frame of personal-care applications, ethoxylated alcohols often result from the transformation of natural lipids. The nomenclature specific to cosmetic chemicals (i.e., INCI names1) is applied to these nonionics: they are denominated by using the root of the fatty acid name terminated by the suffix ''eth'' (contraction of ''ethoxylated''), directly followed by the ethoxylation degree (e.g., laureth-4, oleth-5, myristeth-7). As some raw materials yield on hydrolysis various fatty chain lengths, the names of the derived nonion-ics are either drawn from the natural source (e.g., laneth-16 for a lanolin-derived nonionic) or from the fusion of the constitutive fatty chains (e.g., ceteareth-20 for a combination of cetyl and stearyl).

Alkyl polyethyleneglycol ether or alcohol ethoxylate (e.g., laureth 20 for x=l 1 and n=20)

xl ch3 jy

EO/PO Alkyl Ether (e.g.,propyleneglycol capreth-4 ferx=9, y=l,and 2=4)

Applications of ethoxylated alcohols are numerous in industrial as well as in household products. When properly selected, alkoxylated alcohols are also useful for personal products as good emulsifiers and solubilizers. The cosmetic applications remain, however, limited because of their rather weak foaming capacity. Because they are prone to undergo degradation by oxidation, the following precautions can greatly improve the stability of

1 The International Cosmetic Ingredient Dictionary provides a nomenclature of conventional names for cosmetic ingredients that are defined by the CTFA (The Cosmetic, Toiletry, and Fragrance Association).

ethoxylate nonionics: storage in the dark, minimal air contact, low temperature storage, avoiding storage of diluted products, and the addition of an antioxidant.

EO/PO Block Polymers

These polymeric surfactants have some similarity with the previously discussed alkoxy-lated alcohols. They consist in the combination of the assembly of PPG (hydrophobic part) and PEG chains (hydrophilic part). Such surfactants are known under the denomination ''poloxamers'' (INCI name) and are called EO/PO block copolymer nonionics. A major property of EO/PO nonionics is their low-foaming profile. As straight EO nonionics, EO/ PO copolymers exhibit the cloud point phenomena. EO/PO nonionics are also mild surfactants.

These surfactants are especially useful for applications in which foaming must be significantly depressed, such as automatic dishwashing detergents, laundry detergents, and rinse aids. Because of their mildness, EO/PO block polymers also find applications in cosmetic products. They are generally used as emulsifying, solubilizing, or fluidizing agents.

Alkyl Polyglucosides

Alkyl polyglucosides are most often known by the simple abbreviation APG. APGs are produced by the alkylation of short-chain glucosides resulting from acidic alcoholysis of polysaccharides such as starch. Commercial products consist of mixtures of mono-, di-, and triglucosides. Accordingly the glucosidic chain varies between 1.2 and 3 depending on the production conditions. Surfactants of this class are good emulsifiers and provide good wetting and foaming profiles. Alkyl polyglucosides are compatible with all other surfactants. They show good chemical stability at neutral and alkaline pH, and are impaired under acidic conditions (pH <5).

APGs are used in detergents and personal-care cleansers (e.g., shampoos). They are claimed to be very mild for skin as well as to reduce the skin irritation potential of anionics. Additionally, they impart an excellent skin feel. Their thickening effect in the presence

of anionics and their foam stabilization capacity are also exploited in personal-care applications.

Ethoxylated Oils and Fats

This class of surfactants essentially covers ethoxylated derivatives of lanolin (i.e., aliphatic alcohols and sterols, fractionation products of wool fat) and of castor oil (i.e., fatty acids extracted from ricinus seeds). Ethoxylated products of lanolin and castor oil are good and excellent emulsifiers, respectively. These surfactants are mainly used in the cosmetic industry; their major interest is to offer the possibility of claims based on the natural origin of the constitutive surfactant systems.

Alkanolamides

Straight Alkanolamides

Alkanolamides are N-acyl derivatives of monoethanolamine and diethanolamine.

. CH2CH2OH

R CO NH CH2CH2OH Mo 110 al kano 1 amide

CH2CH2OH Dialkaiiol amide

ch2ch2 ocor

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