Emulsions, surfactants and pigments are used in personal care products.
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Cosmetic products combine several chemical systems to produce a desired effect on skin or hair. Creams and lotions are oil-in-water or water-in-oil emulsions stabilised by emulsifiers, with humectants such as glycerol to retain moisture and preservatives to prevent microbial growth. Sunscreens rely either on UV absorbers such as avobenzone or on mineral particles such as zinc oxide and titanium dioxide that scatter and reflect UV light. Shampoos and cleansers use surfactants that lower surface tension and lift oils and dirt. Permanent hair dyes depend on oxidation chemistry that forms coloured molecules inside the hair shaft.
Key ideas: Products are emulsions (oil in water creams, water in oil lotions) stabilized by surfactants, plus humectants (glycerol), thickeners, preservatives (parabens), colors and fragrance. Sunscreens use UV absorbers (organic, avobenzone) or mineral blockers (zinc oxide, titanium dioxide). Skin surface pH is about 4.5 to 5.5, so mild products match it. SPF measures UVB protection.
Common mistakes and connections: Misconception: SPF 100 gives twice the protection of SPF 50; SPF 30 blocks about 97 percent and 50 about 98 percent. Hair products depend on keratin disulfide bonds (perming breaks and reforms them). Links to surfactants and soap, polymers and emulsions.
Sunscreen filters absorb UV light. Octinoxate absorbs mainly UVB near 310 nm and avobenzone absorbs UVA near 357 nm. The interactive lesson shows this as a live animation or chart.
SPF is a measure of protection against UVB, the wavelengths that cause sunburn.
Emulsions, surfactants and pigments are used in personal care products.
Cosmetic Chemistry is a intermediate topic in Biochemistry, Environment & Industry. It builds on the vocabulary of beginner topics in this area.
Study these earlier topics in Biochemistry, Environment & Industry first: Food Additives, Maillard Reaction, Chemistry of Cooking.
The next topics in Biochemistry, Environment & Industry are Plastics and Thermoplastics and Thermosets.
Yes. The interactive lesson includes a self-check question on Cosmetic Chemistry, and the Biochemistry, Environment & Industry quiz draws on every topic in this area.
Cosmetic Chemistry is topic 51 of 127 in Biochemistry, Environment & Industry.
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