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Schematic diagram of surfactants.
1 Hydrophilic part
2 Lipophilic (hydrophobic) part |
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Until today, soap has been
the product of a chemical reaction of natural fats and alkaline lye.
The use of conventional alkaline soap has some disadvantages, especially
for sensitive skin.
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Soap scum formation when used with
hard water. This is accompanied by an inactivation of the surfactant's
properties. Carbonate salts are deposited on the skin and hinder
the restoration of oils to the skin. It becomes raw. |
Development of syndets
These disadvantages of soap led the scientific community to search
for new body cleansing substances. As a result of these efforts, the
end of the 1950's, the era of synthetically produced detergents, the
syndets, began. Syndets have distinct
advantages over alkaline soaps:
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no alkalizing effort, so an acidic pH can be
set (physiological value 5.5) |
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therefore also suitable for skin with a reduced
alkali reducing capacity |
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no formation of insoluble soap scum |
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little swelling of the horny layer |
As a result of their manifold advantages, the
syndets, in solid and liquid form, have gained a firm place in skin
cleansing - especially for diseased skin.
Surfactants as active cleansing agents
Surfactants are molecules or ions that are comprised of a very water-soluble
(hydrophilic) part, the head, and a fat-soluble (lipophilic) long-chained
segment. Surfactants accumulate preferably at interfaces, which the
hydrophilic part is orientated towards the water and the lipophilic
part towards the oil phase (e.g. lipophilic dirt). |
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The currently popular expression "syndet" comes from the syllables
"syn" for synthetic and "det" from detergent. Detergents refer to
cleaning agents of all kinds, including soaps and synthetic surfactants.
The term "synthetic surfactant" is sometimes used as a synonym for
"syndet". |
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The
importance of the surfactant components
Individual surfactants have specific properties,
such as the ability to create foam (anionic surfactants), or leave
behind a pleasant sensation on the skin (amphoteric surfactants).
Therefore, most cleansing products consist of a mixture of surfactants.
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Besides active cleansing
agents, the term surfactant is used to describe emulsifiers, foaming
agents, solvents and other similar substances. |
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The skin compatibility
of the surfactants is also variable. Even within a class of surfactants,
the skin compatibility varies: from the group of anionic surfactants,
sodium lauryl sulphate has a marked irritation potential, while other
anionic surfactants, for example sodium laureth sulphate and sodium
sulphosuccinatex display a much better skin compatibility because
of a slightly altered molecular structure.
By combining different surfactants, the skin compatibility can be
influenced: for example, when combined with an amphoteric surfactant
the skin irritating sodium lauryl sulphate achieves a much better
skin compatibility.
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more
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