Transcript Chemistry for Cosmetics

Chemistry
for
Cosmetics
Dr Lida Schoen
Amsterdam
Human skin
Lida Schoen
Chemistry of hair and skin products
2
‘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.
Lida Schoen
Chemistry of hair and skin products
3
Cleaning the skin: water and soap
Lida Schoen
Chemistry of hair and skin products
4
Washing dirt from textiles
with water and soap
Lida Schoen
Chemistry of hair and skin products
5
‘Cosmetic’ cleaners
Showergel (=shampoo)
Lida Schoen
Chemistry of hair and skin products
6
‘Cosmetic’ emulsion
•
•
•
•
Water
Oil
Emulsifier
Additions
– Perfume
– Colour
Lida Schoen
Chemistry of hair and skin products
7
Emulsion: micro
Lida Schoen
Chemistry of hair and skin products
8
Emulsion: macro
Lida Schoen
Chemistry of hair and skin products
9
Cream
• 2-3% emulsifier + thickener (for stabilisation)
• 10% oil like
– mineral like paraffin (cheap, doesn’t deteriorate)
– vegetable like avocado (what’s good to eat …),
– animal like mink (snob appeal)
• Water
• Perfume
• Additive, like
– dihydroxyacetone (artificial tanning)
– herbals
Lida Schoen
Chemistry of hair and skin products
10
Flowers, herbals
Lida Schoen
Chemistry of hair and skin products
11
Hair under microscope
Lida Schoen
Chemistry of hair and skin products
12
Chemistry: keratin
• Hydrogen bridges
• Ion-ion (salt) bonds
• Disulfide (sulpher)
bonds
Lida Schoen
Chemistry of hair and skin products
13
Keratin (2)
Lida Schoen
Chemistry of hair and skin products
14
Keratin (3)
pH = 5,5
Lida Schoen
Chemistry of hair and skin products
15
Keratin (4)
cystin
Lida Schoen
Chemistry of hair and skin products
16
All bonds (schematic)
Lida Schoen
Chemistry of hair and skin products
17
Lida Schoen
Chemistry of hair and skin products
18
Melanin in cortex
Eumelanin
• black-brown;
• large molecules;
• easy to light up.
Pheomelanin
• yellow-red;
• smaller molecules;
• difficult to light up.
Lida Schoen
Chemistry of hair and skin products
19
Lida Schoen
Chemistry of hair and skin products
20
Hair colour
Lida Schoen
Chemistry of hair and skin products
21
Hair cleaning: shampoo
Detergent: sodium lauryl (=C12) ether
sulphate:
•
•
•
•
cheap
skin friendly
good foam
easy to thicken (with NaCl)
Lida Schoen
Chemistry of hair and skin products
22
Ether sulfates
• Vegetable oil, after hydrolysation and
reduction, ethoxylation with ethylene oxide
• Alkyl alcohol esterified with sulphuric acid:
CH3-(CH2)10-CH2(OCH2CH2)n)OSO3- Na+
with 1<n<4
Lida Schoen
Chemistry of hair and skin products
23
Thickener: electrolyte
• detergent in water:
micelles
• NaCl (3-4%)
Lida Schoen
Chemistry of hair and skin products
24
Conditioner in the past: egg yolk
Egg shampoo:
• Egg yolk: lecithin
Conditioner today: man made
•quat = quaternary ammonium compound
•silicone
Lida Schoen
Chemistry of hair and skin products
25
Hair in form
1775
today
Lida Schoen
Chemistry of hair and skin products
26
Hair gel at school
Carbomer (brand name in Europe):
neutralised cross linked polymer of acrylic
(propene) acid
CH2=CH-COO-Na+
Lida Schoen
Chemistry of hair and skin products
27
Bleaching (1)
• Decomposition of
melanin by oxidation in
alkaline (ammonia)
environment;
• carboxylated derivatives
soluble at higher pH’s.
Lida Schoen
Chemistry of hair and skin products
28
Bleaching (2)
• Bleaching powder: persulphate:
(O3S-O-O-SO3)22 Na2S2O8 -> 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.
Lida Schoen
Chemistry of hair and skin products
29
Types of hair colouring
• Oxidative
– permanent
• Direct
– semi-permanent
– temporarily
Lida Schoen
Chemistry of hair and skin products
30
Hair colouring products
•
•
•
•
•
Natural
Metal
Permanent (synthetic dyes)
Semi-permanent (natural en synthetic dyes)
Temporarily (synthetic dyes)
Lida Schoen
Chemistry of hair and skin products
31
Lida Schoen
Chemistry of hair and skin products
32
Lida Schoen
Chemistry of hair and skin products
33
walnut
henna
Lida Schoen
Chemistry of hair and skin products
34
Semi-permanent hair colouring
• in and under cuticle
• 4-6 washings
• till 30% grey covering
Lida Schoen
Chemistry of hair and skin products
35
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
Lida Schoen
Chemistry of hair and skin products
36
Permanent hair colouring
• Oxidative dyes:
‘development’ with hydrogen
peroxide
• Not washable
• Till 100% grey covering
Lida Schoen
Chemistry of hair and skin products
37
Developers and couplers
Ontwikkelaars = developers
NH2
NH2
NH2
NH2
CH3
NH2
p-Fenyleendiamine
CH3
NH2
OH
Tolueen-2,5-diamine
p-Aminofenol
OH
4-Amino-m-cresol
Koppelaars = couplers
NH2
NH2
NH2
NH2
OH
OH
OH
OH
CH3
m-Fenyleendiamine
Lida Schoen
m-Aminofenol
p-Amino-o-cresol
Chemistry of hair and skin products
Resorcinol
38
Examples of couplings
Lida Schoen
Chemistry of hair and skin products
39
Summary chemical ‘trick’
• Mix two (or more) kinds of 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 much
bigger molecules;
• The big molecules are captured in the cortex,
they can’t leave: permanent hair dye
Lida Schoen
Chemistry of hair and skin products
40
Bath salts
1. Salt
1.
2.
3.
4.
kitchen salt:
soda :
bicarbonate:
phosphate:
NaCl
Na2CO3
NaHCO3
Na3PO4
(cheap, crystals)
(softener)
(solubility)
(complexer)
2. Perfume
3. Colour (water soluble food colour)
4. Extra (chamomile, herbals)
Lida Schoen
Chemistry of hair and skin products
41
Perfume (1)
• Natural (past) and synthetic (aldehydes,
ketones, esters)
• Mixture of 3 groups ‘notes’:
– Top;
– Middle;
– Base.
Lida Schoen
Chemistry of hair and skin products
42
TOP
citrus
green
fruity
lime, lemon ,
mandarin, orange, grass, apple,
pineapple, cassis, raspberry, peach
MIDDLE
jasmin, rose, violet,
muguet
floral
sandalwood,
cedarwood,
ambery,
musky,
vanilla,
sweet hay
BASE
woody
powdery
Lida Schoen
Chemistry of hair and skin products
43
‘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)
Lida Schoen
Chemistry of hair and skin products
44
Dilution
• With min 70% alcohol
• Denaturated (tax reasons) with bergamot
(citrus) or DEP (di-ethylphtalate)
• Perfume:
• Eau de Toilette:
Lida Schoen
20% oils
5% oils
Chemistry of hair and skin products
45
Allure – Fragrance Description
From the Chanel website:
• The concept of Allure was Coco Chanel’s 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,
you’ll find bergamot, mandarin, water lily & magnolia,
jasmine and may roses, vetiver and finally, the velvety
sensuality of vanilla.
Lida Schoen
Chemistry of hair and skin products
46