How Much Do You Know About Shampoo Composition in Hair Care?

Shampoo is a hair care product, typically in the form of a viscous liquid, that is used for cleaning hair.

Shampoo combines a surfactant, most often sodium lauryl sulfate or sodium laureth sulfate, with a co-surfactant, most often cocamidopropyl betaine in water to form a thick, viscous liquid. Other essential ingredients include salt (sodium chloride), which is used to adjust the viscosity, a preservative and fragrance. Other ingredients are generally included in shampoo formulations to maximize the following qualities:

pleasing foam
ease of rinsing
minimal skin and eye irritation
thick or creamy feeling
pleasant fragrance
low toxicity
good biodegradability
slight acidity(pH less than 7)
no damage to hair
repair of damage already done to the hair
Many shampoos are pearlescent. This effect is achieved by the addition of tiny flakes of suitable materials, e.g. glycol distearate, chemically derived from stearic acid, which may have either animal or vegetable origins. Glycol distearate is a wax. Many shampoos also include silicon to provide conditioning benefits.

Commonly used ingredients

Ammonium chloride
Ammonium lauryl sulfate
Glycol
Sodium laureth sulfate is derived from coconut oils and is used to soften water and create a lather. There was some concern over this particular ingredient circa 1998 as evidence suggested it might be a carcinogen. This has yet to be disproved, as many sources still describe it as irritating to the hair and scalp.
Sodium lauroamphoacetate is naturally derived from coconut oils and is used as a cleanser and counter-irritant. This is the ingredient that makes the product tear-free.
Polysorbate20 (abbreviated as PEG(20)) is a mild glycol-based surfactant that is used to solubilize fragrance oils and essential oils, meaning it causes the liquid to spread across and penetrate the surface of a solid (i.e. hair).
Polysorbate80 (abbreviated as PEG(80)) is a glycol used to emulsify (or disperse) oils in water (so the oils do not float on top like Italian salad dressing).
PEG-150 distearate is a simple thickener.
Citric acid is produced biochemically and is used as an antioxidant to preserve the oils in the product. While it is a severe eye irritant, the sodium lauroamphoacetate counteracts that property. Citric acid is used to adjust the pH to approximately 5.5. It is a fairly weak acid which makes the adjustment easier. Shampoos usually are at pH 5.5 because, at a slightly acidic pH, the scales on a hair follicle lie flat, making the hair feel smooth and look shiny. It also has a small amount of preservative action. Citric acid, as opposed to any other acid, will prevent bacterial growth
Quaternium-15 is used as a bacterial and fungicidal preservative.
Polyquaternium-10 has nothing to do with the chemical quaternion-15; it acts as the conditioning ingredient, providing moisture and fullness to the hair.
Di-PPG-2 myreth-10 adipate is a water-dispersible emollient that forms clear solutions with surfactant systems
Chloromethylisothiazolinone, or CMIT, is a powerful biocide and preservative.