Abstract
Emollients are essential ingredients in all types of skin care products. The selection of the emollient phase will determine skin feel, moisturization capacity, and stability of the formulation. Emollients can be classified according to their chemical composition or by their physicochemical properties. The basic building blocks of most emollients are long chain hydrocarbons, often combined with alcohols and acids in the form of esters. The raw materials are derived from petrochemical or natural sources, such as vegetable oils and fats.
By varying the molecular structures and the composition of the emollients, properties such as rheology and polarity can be adjusted to meet the requirements on moisturization, sensory properties, and delivery of actives. The rheological properties of the emollient can influence the lubricity and spreading properties of the formulation. The polarity of the emollient is linked to the delivery of actives and to the interaction between the formulation and skin.
When selecting emollients for a formulation, the stability in terms of hydrolysis and oxidation must be considered. Esters can be hydrolyzed to the corresponding alcohol and acid if the formulation is too acidic or alkaline. Oxidation will produce off-flavors and can also lead to the formation of inflammatory and irritating breakdown products.
The selection of an emollient mixture for a formulation must also consider parameters such as purity, biodegradability, and sustainability, leading to the development of new processes and types of emollients in the future.
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Alander, J.T. (2012). Chemical and Physical Properties of Emollients. In: Lodén, M., Maibach, H. (eds) Treatment of Dry Skin Syndrome. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-27606-4_26
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DOI: https://doi.org/10.1007/978-3-642-27606-4_26
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