Short for surface-active agent. Surfactants make the modern world a clean, healthy place in which to live. Humans certainly weren’t using them on a regular basis for much of recorded history. Nowadays, they’re key chemicals in cosmetics, industrial cleaning, oil & gas, and food.
I enjoy talking about surfactants for a few reasons; principal among them is my career started in formulations of haircare. It was inevitable to become an expert on the subject. Second, while figuring out what I wanted to stick with, I worked in a few industries. To my surprise, surfactants are used in oil & gas for cleaning tanks, cleaning sludge, cleaning water, and drilling. Oil & gas is one of the top markets for surfactants, fyi. Third, they’re rad chemicals. That they have so many applications is a testament to their unique chemistry as a group. Being amphiphilic gives this group of compounds many uses.
In the cosmetics industry, you’re likely to encounter 4 different kinds of surfactants, characterized by their charge(s) on the head group:
- Anionic: negatively charged hydrophilic head
- Cationic: positively charged hydrophilic head
- Nonionic: zero charge hydrophilic head
- Amphoterics (zwitterionic): dual charge on hydrophilic head
Each surfactant class has their pros and cons. The most effective are the anionic, of which the infamous Sodium Lauryl/Laureth Sulfates are a part. Great cleansers, though they might be harmful to aquatic life life and strip hair and skin of their natural oils. Sulfonates are slightly better options, but warning, they do use ethylene are a starting source. Amino acid based surfactants like Sodium Cocoyl Glutamate and Sodium Cocoyl Glycinate are good alternatives with good lather, soft foaming, and gentle washing. They’re also made from natural sources. Furthermore, at acidic pH (4.5-6.0), they increase in viscosity, generate more foam, and lather improves.
Cationic surfactants include Quaternized Ammonium Compounds (Quats), Alkoxylate Amines, and Amines. In cosmetic haircare, positive charge surfactants are used mainly for the conditioning effects so let’s focus on Quats. These compounds have anywhere from one to several ammonium groups that gravitate to hair. Hair happens to be slightly negative in charge. The result is that Quats leave air feeling soft and with more volume. They’re difficult to formulate with when working with anionic surfactants.
Nonionic surfactants are better know by their functionalities, namely emulsifiers, esters, and solubilizers. In effect, these uses make nonionic surfactants the most widely used out of the 4 groups. Glyceryl Stearate SE, Sorbitan Stearate, Stearyl Alcohol and Cetyl Alcohol are all surfactants used for their emulsification properties in creams and lotions to give body and feel. Their use as solubilizers include the following: Polysorbate 20, Caprylyl/Capryl Glucoside, and Tego Solve 61. Esters commonly used are Squalane, MCT oil, and Coco-Caprylate/Caprate. Alkyl Polyglucosides are decent choices for haircare surfactants. As you can see, nonionic surfactants makeup (no pun intended) much of the personal care/cosmetics world.
The last class of surfactants are the Amphoterics. These are likely to be found in shampoos, body washes, and other cleansers. Two of the most widely used are Cocamidopropyl Betaine and Cocamidopropyl Hydroxysultaine, as they make good secondary surfactants that increase foaming, increase viscosity, and reduce irritation. Sodium Lauroamphodiacetate is another good choice.
A good summary for the types of surfactants encountered while in this industry. With everything else within this industry, the sky is the limit as Formulators create novel products and scientists keep making new raw materials from naturals sources. It’ll be interesting to see what will be around in the next 20 years.
Greengen Labs 