What Makes a No-Tears Shampoo

KEY TERMS intermolecular forces hydrogen bonding polymer 

Shampoo manufacturers provide a wealth of products to satisfy a range of consumer preferences. What kind of chemical ingredients are included to ensure a mild shampoo and guarantee a no-tears formula  

As the central function of a shampoo is to cleanse the hair, the primary ingredient of a shampoo is a detergent (also known as a surfactant). Many shampoos, particularly those targeted for babies and children, claim to cause no eye irritation or sting. A no-tears formulation achieves this claim by carefully adjusting the nature of the surfactants. In particular, the identity and concentration of surfactants with an ionic or charged portion are controlled to minimize both eye and skin irritation. 

A surfactant is a molecule that is characterized as amphiphilic, i.e., containing both a discrete hydrophilic (water-soluble) or polar portion and a well-defined hydrophobic (oil-soluble) or nonpolar fragment. The hydrophilic portion of the molecule is called the surfactant headgroup the hydrophobic portion of a surfac- 

Cationic surfactants contain a positively charged headgroup and are typically used as conditioners to improve hair manageability and reduce static. Cationic surfactants are especially irritating to eyes when used in high concentrations but are safe and useful in low amounts. Quatemium-15 (chloroallyl methanamine chloride, Fig. 7.9.4) is a cationic surfactant included in shampoo formulations 

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