Surfactants are used in many cosmetics as foaming agents, cleansers, emulsifiers, conditioners and solubilizers or dispersants. The word surfactant comes ‘surface active agent’. They are ingredients that lower the surface tension of a liquid, or another way to put it is that they are ‘wetting agents’.
single surfactant molecule has two ends; one that is attracted to water
(hydrophilic) and one that is attracted to oil (hydrophobic). This
property of having both water soluble and oil soluble parts is called
amphiphilic (which in my opinion is a very fun word to say). Each end of
the molecule can associate with a different environment and bridging
them hence solubilizing one in the other enabling dirt and oil molecules
to loosen and dissolve in the water.
Soaps are common surfactants but are seldom used in cleansers
and shampoos because of their residue. The most common non soap
surfactants remain sodium lauryl sulfate and sodium laureth sulfate
which are both very effective cleansers but some people fine them
Many modern surfactants are made from oleochemicals
(vegetable derived) rather than petrochemicals (petroleum derived) and
are also biodegradable. Oleochemicals, or fats used to synthesize these
surfactants include palm and coconut oils. These surfactants include the
anionic alkyl polyglucosides (decyl, lauryl, and octyl), which are made
from fatty alcohols from coconut or palm and glucose from corn starch
using green chemistry. Their names vary depending upon the length of the
The lactylates (sodium lauroyl and sodium stearoyl) are food
grade emulsifiers made from coconut oil and milk sugar. They are great
moisturizers and provide extended fragrance release.
Other natural surfactants include lauryl glucose carboxylate
which provides added foaming ability. Glutamate surfactants such as
disodium cocoyl glutamate, sodium cocoyl glutamate are mild and made
from amino acids. They provide fine lather, good cleansing and are
rapidly biodegradable. Vegetable proteins can also be a basis for
surfactants such as potassium undecylenoyl hydrolysed soy protein and
sodium lauroyl oat amino acids.
Anyone who has taken a physiology class has heard of
surfactants that naturally occur in the lungs. Here they prevent the the
lungs from collapsing on themselves due to the surface tension of the
moisture in them. The alveolar cells of the lungs secrete a lipoprotein
that acts as a surfactant. Because the alveoli (air sacs) of the lungs
are coated in moisture the surface tension there encourages collapsing
of the alveoli. If the alveoli collapsed, air would not be able to
enter. It is the surfactant that allows the alveoli to remain open.
Interestingly, during fetal development surfactant production begins
rather late. Babies born prematurely before 28 weeks suffer infant
respiratory distress syndrome (IRDS) because their lungs cannot stay
open and hold air. Follow this link for more information on surfactants.