WHAT IS A SURFACTANT?
A surfactant or surface active agent is one that possesses one distinct portion of the molecule that is polar and hydrophilic (water-loving), and one portion that is non-polar and hydrophobic (water-fearing). This dual nature enables these molecules to interact favorably with water and water-soluble molecules as well as water-insoluble molecules.
In many surfactants such as sodium lauryl sulfate, the hydrophilic portion is found to exist on a terminal end of the molecule, and for this reason, it is often referred to as the head group. The hydrophobic portion of these linear surfactant molecules is typically an alkyl or aryl containing chain, which is referred to as the tail group.
Surfactants cleanse and build foam by acting at the surface between fat and water (surface-active agents or surfactants). They are able of being mixed with water and fat of the skin, allowing dirt to be removed. Based on their cleansing power surfactants are classified into primary and secondary or co-surfactants. Based on the chemical structure there are anionic, amphoteric, non-ionic, and quaternary agents. Surfactants form the base of all personal cleansing products and can also have wetting, conditioning, defatting, emulsifying, & thickening effects. The most common anionic surfactants have a sulfate (such as SLS), sulfonate, phosphate, or carboxylate (soaps) functionality as the head group, while cationic surfactants are often tertiary or quaternary salts of alkyl amines (cetrimonium chloride). Ionic surfactants are available in a salt form with an appropriate alkali metal or ammonium counterion (typically sodium or ammonium).
Sodium lauryl sulfate is probably the most commonly used anionic surfactant in the personal-care Products. It is relatively inexpensive, foams quickly and is a fairly efficient cleanser. This molecule has 12 carbon atoms in its hydrophobic tail group and has a low critical micelle concentration, which means it has relatively good cleansing capabilities. The downside is that it can be irritating to the skin, can be quite harsh to delicate, dry hair. This is less the case when the formula which contains it has sufficient conditioning agents and co-surfactants present to minimize this effect. It has also acquired quite a reputation primarily due to misinformation spread through the internet for being a health hazard.
Sodium Laureth Sulfate, which is a slightly larger molecule than SLS modified by the addition of ether groups, has the ability to form larger micelles and is consequently a more efficient and harsher cleanser. This is also true for ammonium lauryl sulfate, ammonium laureth sulfate, and sodium myristyl sulfate and sodium myreth sulfate, but SLES and ALES are less irritating to the skin and eyes, which has possibly allowed them to enjoy an erroneous reputation for being gentler to the hair as well.
Sodium lauryl sulfate (top figure) and sodium lauryl ether sulfate. The ammonium versions of these molecules have an NH4+ counter ion in place of the sodium ion.
Sodium coco or cocoyl sulfate is sometimes seen on the labels of products wishing to market themselves as natural, gentle and luxurious. It is touted for being derived from coconut oil, which is true. It is typically a combination of sodium lauryl sulfate (usually around 50%) and sodium myristyl and palmityl sulfate (longer chain hydrocarbon tails). Although this is derived from coconut oil, it goes through a rigorous chemical reaction and purification process, and the result is a surfactant mixture
Sulfosuccinates are another kind of sulfate surfactant seen in hair and skin-care products. These ingredients possess two hydrophobic tails, which is a very different molecular architecture than the straight-chain sulfates. Molecules of this type are not as efficient at packing into micelles and are very mild cleansing agents. For this reason, they are not excessively drying to the skin or hair and should not be of concern, even though they retain their status as “sulfates.”
Magnesium sulfate, an ingredient often used as a curl enhancer in styling products, is not a surfactant but rather an inorganic crystalline compound. This material does not strip away moisture or oils from the hair or dry the hair in the same manner as a sulfate surfactant. It can create frizzy or dry-textured hair.
How to Select a Sulfate Shampoo
Shampoo formulation was merely made up of water, surfactant, and preservative, it might seem pretty cut and dried to avoid most of your sulfate-based surfactants. Sulfate can do wonders if formulated with other co-surfactants, moisturizer and conditioning polymers.
However, in most formulations, there are co-surfactants present, such as fatty alcohols, nonionic surfactants and amphoteric surfactants (cocamidropropyl betaine) — many of which help to reduce the drying tendency of the cleanser. Also, most formulations contain additives such as moisturizing oils and conditioning polymers that can help prevent damage to the hair. Additionally, the composition by weight of each component in the formulation is important to the overall performance of the product.
If you are attempting to avoid harsh shampoos, it is probably best to make sure you find a product that contains milder surfactants, lots of moisturizing agents, and little, if any of the linear chain sulfates, look for ones that have SLS or SLES lower down the ingredient list, and make sure the list contains other mild co-surfactants and moisturizing agents.
The sulfate-free trend has emerged from beauty salons into the mainstream. Originally meant to convey resistance to color-fading on dyed hair, the sulfate-free concept has grown to include low skin irritation claims in Shampoo, body washes, and other cleansing products.
The Chemistry of Sulfate-Free Shampoo
Chemistry is a defined Science. When you change one element of a formula or ingredient, you change composition, which in turn changes the ingredient. For example, Sodium Laurel sulfate becomes sodium laurel Sulfonate, simply by changing o to x in the ingredient design. The product is now sulfate free or so they claim.
Marketers love these slight variations that allow them to claim a healthier point of difference in their products, giving the consumer the impression produced is safe, healthier and cleaner, in reality, these new surfactants although gentler but are sulfate compounds.
What most consumers don’t know is that some companies are choosing chemical that is often stronger and harsher than sulfate. These substitutes include Coco amide DEA, Cocomide MEA, PEG, Propylene Glycol, Hydroxysultaine.
The most widely-used sulfate-free claims in the Personal Care market are
- Less color loss on dyed hair even with repeated shampooing
- Less stripping of natural oils from skin and hair
- Mild and gentle to skin, scalp, and hairSurfactants including:
There are challenges when formulating with sulfate-free
- Foam volume tends to be lower than sulfated systems
- Foam character is denser compared to sulfate surfactants
- Viscosity building may be different from sulfate surfactants
Who should use sulfate free /Low Sulfate Shampoo?
- You have a sensitive skin such as eczema.
- You have dry hair.
- You are experiencing hair loss.
- You dye your hair and would like to maintain the color un-faded for a longer time.
How Do I Find Sulfate-Free Products?
In common terms, these new generations of surfactants acts as a cousin to their original counterparts. The good news is that truly sulfate-free hair products are out there! True Sulfate Free Shampoos are derived from gentler, plant-extracts and amino acid, seed oils, such as palm or coconut oil, and possess numerous advantages over their chemically manufactured counterparts.
Look for products that contain many of the following ingredients:
- Fruit Amino Acids – Oat and Apple amino acids obtained by acylation of this fruits, this are Anionic Surfactant, extremely gentle, nondrying and offers unctuous and rich Foam.
- Glutamates – Amino acid-based surfactants, these are often found in certified organic products. Hypoallergenic and non-comedogenic, Glutamates are also known for being one of the mildest active agents on the market.
- Gulcosides – Ecocert approved, they are obtained from renewable, plant-derived raw materials, such as vegetable oils and starch. Lauryl Glucoside, a surfactant made from coconut oil and sugar, is one of the gentlest cleaners on the market. Because it is naturally derived, Lauryl Glucosides facilitate effective cleansing with a reduced potential for irritation.
- Taurates and Fatty Acid Isethionates – Derived from the coconut fatty acid, they have an excellent cleansing ability and hair conditioning effect; all while being considered exceptionally mild for the hair, skin, and eyes.
- Amino Acid Sulfosuccinates – Known for their mild and anti-irritant properties, these surfactants are especially suitable for products made for delicate skin and baby shampoos due to their super gentle nature.
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