Chemistry for Cosmetics

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ChemistryforCosmetics

• Dr Lida Schoen
• Amsterdam

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Human skin
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Dirt on the skin

• water soluble (sweat)
• oil soluble (sebum, grease)
• non soluble (sand, skin flakes).
• Rubbing with water and soap can remove all three.

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Cleaning the skin water and soap
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Washing dirt from textiles
with water and soap
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Cosmetic cleaners
Showergel (shampoo)
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Cosmetic emulsion

• Water
• Oil
• Emulsifier
• Additions
• Perfume
• Colour

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Emulsion micro
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Emulsion macro
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Cream

• 2-3 emulsifier thickener (for stabilisation)
• 10 oil like
• mineral like paraffin (cheap, doesnt
  deteriorate)
• vegetable like avocado (whats good to eat )
• animal like mink (snob appeal)
• Water
• Perfume
• Additive, like
• dihydroxyacetone (artificial tanning)
• herbals

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Flowers, herbals
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Hair under microscope
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Chemistry keratin

• Hydrogen bridges
• Ion-ion (salt) bonds
• Disulfide (sulpher) bonds

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Keratin (2)
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Keratin (3)
pH 5,5
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Keratin (4)
cystin
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All bonds (schematic)
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Melanin in cortex

• Eumelanin
• black-brown
• large molecules
• easy to light up.
• Pheomelanin
• yellow-red
• smaller molecules
• difficult to light up.

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Hair colour
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Cleaning hair shampoo

• Detergent sodium lauryl (C12) ether sulphate
• cheap
• skin friendly
• good foam
• easy to thicken (with NaCl)

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Ether sulfates

• Vegetable oil, after hydrolysation and reduction,
  ethoxylation with ethylene oxide
• Alkyl alcohol esterified with sulphuric acid
  CH3-(CH2)10-CH2(OCH2CH2)nOSO3- Na with 1ltnlt4

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Thickener electrolyte

• detergent in water micelles
• NaCl (3-4)

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Conditioner in the past egg yolk

• Egg shampoo
• egg yolk lecithin

Conditioner today man made

• quat quaternary ammonium compound
• silicone

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Hair in form 1775
today
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Hair gel at school

• Carbomer (brand name in Europe) neutralised
  cross linked polymer of acrylic (propene) acid
• CH2CH-COO-Na

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Bleaching (1)

• Decomposition of melanin by oxidation in alkaline
  (ammonia) environment
• carboxylated derivatives soluble at higher pHs.

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Bleaching (2)

• Bleaching powder persulphate(O3S-O-O-SO3)2-
• 2 Na2S2O8 -gt 2 Na2S2O7 O2
• Hydrogen peroxide,(max. 12, pH 4), optimum
  melanin bleaching at pH ? pKa (11,5) of the
  peroxide-anion
• In practice pH 10. H2O2(aq) 12 not stable at
  pH 10.

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Types of hair colouring

• permanent
• semi-permanent
• temporarily

• Oxidative

• Direct

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Hair colouring products

• Natural
• Metal
• Permanent (synthetic dyes)
• Semi-permanent (natural en synthetic dyes)
• Temporarily (synthetic dyes)

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walnut
henna
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Semi-permanent hair colouring

• in and under cuticle
• 4-6 washings
• till 30 grey covering

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Metal dyes

• Acetates or sulphates of lead, silver, iron,
  copper, cobalt, bismuth, manganese, zinc
• Sulphide bonds with sulphur from keratin
• Toxic properties!
• Sensitive to oxidation

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Permanent hair colouring

• Oxidative dyes development with hydrogen
  peroxide
• Not washable
• Till 100 grey covering

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Developers and couplers
Developers
couplers
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Examples of couplings
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Summary chemical trick

• Mix two (or more) types small molecules
• cover hair with mixture
• small molecules intrude the hair cortex (higher
  pH will help to open cuticula)
• inside the cortex small molecules react to form
  bigger molecules
• The big molecules are captured in the cortex,
  they cant leave permanent hair dye

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Bath salts

1. Salt
2. kitchen salt NaCl (cheap, crystals)
3. soda Na2CO3 (softener)
4. bicarbonate NaHCO3 (solubility)
5. phosphate Na3PO4 (complexer)
6. Perfume
7. Colour (water soluble food colour)
8. Extra (chamomile, herbals)

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Perfume

• Natural (past) and synthetic (aldehydes, ketones,
  esters)
• Mixture of 3 groups notes
• Top
• Middle
• Base.

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TOP
lime, lemon , mandarin, orange, grass,
apple, pineapple, cassis, raspberry, peach
citrus green fruity
MIDDLE
jasmin, rose, violet, muguet
floral
sandalwood, cedarwood, ambery, musky, vanilla,
sweet hay
BASE
woody powdery
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Our Chanel Allure

• citrus 15 drops (top)
• lily of the valley 8 drops (top/ middle)
• rose 2 drops (middle)
• jasmin 10 drops (middle)
• floral bouquet 5 drops (middle)
• sensual 10 drops (base)

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Dilution

• With min 70 alcohol
• Denaturised (tax reasons) with bergamot (citrus)
  or DEP (di-ethylphtalate)
• Perfume 20 oils
• Eau de Toilette 5 oils

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Allure Fragrance Description

• From the Chanel website
• The concept of Allure was Coco Chanels ideal an
  innocent seduction without artifice, an
  unforgettable elegance transcending words and
  conventions.
• Fragrance family floral, fresh, oriental. A
  faceted fragrance that mixes notes of the Orient
  with abstract flowers.
• A simple jewel that combines 6 complex facets. In
  Allure, youll find bergamot, mandarin, water
  lily magnolia, jasmine and may roses, vetiver
  and finally, the velvety sensuality of vanilla.