The cosmetic ingredient nomenclature system INCI covered by the law of the European Union contains the name of Ceteareth-12. Chemically, the substance is a mixture of cetyl and stearyl alcohols ethoxylated with twelve moles of ethylene oxide. Due to the physical and chemical properties of Ceteareth-12, the substance can be used as a non-ionic surfactant. The structure comes from a broad range of well-known surfactants with multi-directional uses, i.e. ethoxylated fatty alcohols, and its structural precursor could be a high molecular weight alcohol of vegetable, animal or synthetic origin. The number assigned to Ceteareth-12 in the globally structured CAS system is 68439-49-6.
Under room conditions, Ceteareth-12 comes as a solid whose appearance and consistency resemble soft white wax. Similarly to other chemical compounds derived from the group of ethoxylated fatty alcohols, Ceteareth-12 has very good wetting, emulsifying and dispersing properties. It is a surfactant, also called an emulsifier. This means that it provides a link for the two – water and oil – phases of the emulsion, thus contributing to the right form of the cosmetic. Like every emulsifier, Ceteareth-12 consists of two parts with opposite properties – hydrophobic and hydrophilic, thus helping to convert immiscible liquids, one of which is the oil phase, and the other is the water phase. The system that is then formed is called an emulsion. The hydrophile-lipophile balance, HLB, which is a characteristic feature of emulsifiers, determined for Ceteareth-12 is 13.5. This coefficient is calculated on the basis of the number of hydrophilic groups as compared to the lipophilic groups present in the structure of a molecule. The HLB value of 13.5 shows it is an O/W (oil-in-water) emulsifier. This means that Ceteareth-12 acts by dispersing drops of the oil phase in the continuous water phase. As opposed to W/O (water-in-oil) emulsions, these emulsions are not diluted easily in water, because they form what are known as clusters. Ceteareth-12 is very well soluble in this solvent, but on account of its form, it is advisable to use a heated solvent, which will make the substance liquid. It is the easiest way to help solve the substance in water, as its solidification temperature is as high as approx. 40oC. Ceteareth-12 has the capacity to emulsify substances such as mineral oils, white spirit, paraffin, xylene as well as vegetable and animal fats. The substance is of moderate foamability and stabilises and improves the quality of foam when used with anionic surfactants. When combined with such agents, it can also form what are known as mixed micelles, thus it improves the consistency of washing agents by acting as a rheology modifier. The activity of Ceteareth-12 does not deteriorate regardless of the hardness of water or added electrolytes. However, it is affected by changes in the environment that result in pH modifications of the solution. As the substance is decomposed by microorganisms under aerobic conditions to carbon dioxide and biomass, Ceteareth-12 is a substance susceptible to aerobic biodegradation.
Due to its surfactant properties, Ceteather-12 is usually used as an oil-in-water emulsifier. On an industrial scale, the substance may be used in processing of soluble oils, textile end-use finishes, anti-foaming emulsions and hydraulic fluids. In cosmetics, it commonly acts as an emulsifier and wetting agent used for example in skin care products, hair conditioners, creams with the SPF protection factor, hair dyes or other colour cosmetics. In the formulations of preparations that contain aqueous and oily ingredients, Ceteareth-12 prevents the separation of phases, helping to spread preparations and the substances they contain in an even and advantageous manner. Its good wettability also helps to spread products as it prevents them from rolling up and gathering on the skin surface. On that account, Ceteareth-12 is a valuable ingredient of creams, cosmetic milks and lotions.
