Ceteareth-18 is the INCI systematic name for a chemical substance from the family of ethoxylated fatty alcohols. The structure of Ceteareth-18 is based on high molecular weight alcohol of natural origin that is mostly present in vegetables. According to its chemical properties, Ceteareth-18 belongs to the group of non-ionic surfactants. Its CAS global identifier is 68439-49-6.
At room temperature, Ceteareth-18 has a solid form and the consistency and appearance of white wax. Its solidification point is already approx. 40oC. Despite a very good water solubility, the high solidification temperature of the substance makes it necessary to use water with a higher temperature to change the state of Ceteareth-18 and form a homogeneous mixture. The reaction of a 1% solution may range from slightly acidic to slightly alkaline, i.e. between 5.5-8.5. The pure substance has the density of 0.97 g/ml at a temperature of 40oC, and the content of water is max. 1% by weight. Ceteareth-18 is also relatively well soluble in other popular solvents such as low aliphatic alcohols or benzene.
Ceteareth-18 is a substance with exceptionally high emulsifying and dispersing properties. As an emulsifier, i.e. a surfactant, it can lower the interfacial tension between the water and oil phases, which reduces the work required to form an emulsion. The adsorption reaction at the surface boundary generates a very durable protective film, which prevents the drops of the internal phase from merging. Emulsifiers are categorised according to the HLB value, i.e. the hydrophile-lipophile balance. Ceteareth-18 is a representative of hydrophilic emulsifiers and its HLB is as high as 16.3. Substances whose hydrophile-lipophile balance coefficient is above 10 are considered to stabilise oil-in-water (O/W) emulsions. As this organic mass is converted by active microorganisms, under aerobic conditions, into carbon dioxide and biomass, Ceteareth-18 may be considered susceptible to aerobic biodegradation. Like most substances in the family of ethoxylated fatty alcohols, it has the ability to form foam; in this case it is moderate foamability. The activity of Ceteareth-18 does not deteriorate in the presence of hard water or with electrolytes added but the substance is sensitive to changes of the pH of the solution. Ceteareth-18 has the capacity to emulsify mineral oils, white spirit, paraffin, xylene, vegetable and animal fats, paraffin wax and waxes.
As a surfactant, Ceteareth-18 has many multidirectional applications. It is most commonly used in formulations as an oil-in-water (O/W) emulsifier, where the aqueous phase is the continuous phase, while an oily substance or oil is the dispersed phase. Substances with such properties are often ingredients of compositions such as moisturising creams, body lotions, hair conditioners and cosmetic milks. Ceteareth-18 is used in all the above-mentioned cosmetics and also in all types of colour cosmetics – hair dyes and cosmetics for the face and body. You can find Ceteareth-18 in facial creams with SPF, body oils and strong anti-breakout formulations. Besides the function of an emulsifier, it also acts as an emollient which forms occlusion on the skin surface, protecting against transepidermal water loss (TEWL) from deeper skin layers. It thus prevents dehydration, regulating the amount of water which leaks from the deepest skin layers outside. On a greater scale, Ceteareth-18 is used in the industry to prepare cutting fluids of the soluble oil type, textile end-use finishes, anti-foaming emulsions and hydraulic fluids. The process of production of water-based acrylic and PVA dispersions, used in the construction industry and in adhesive or paint formulations, is based on emulsion polymerisation. This method uses an oil-in-water emulsifier to polymerise a monomer in a dispersion medium. The emulsification of hydrophobic monomers with emulsifiers such as Ceteareth-18 ensures the stability of both the initial monomer emulsion and the resultant polymer dispersion. If Ceteareth-18 is added to other emulsifiers with lower HLBs, the stablity of emulsions is much improved.
