chemistry in cosmetics

7/27/2019 Chemistry in Cosmetics

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Cosmetics

Dr. Harminder Singh

[email protected]


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Cosmetics are substances used to enhance the

appearance or odor of the human body.

Includes:

skin-care creams,

lipsticks,

powders, perfumes,

deodorants

nail polish,

eye and facial makeup, colored contact lenses, hair colors, hair sprays and gels,

baby products, bath oils,

Prepared By: Dr. Harminder Singh


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Cosmetics are available in several forms for

various uses. Most common are :Emulsions, suspensions and sticks.

Ingredients used are : surfactants, water,emulsifier, active ingredients, thickener, color,

fragrance and preservatives.

The basics of most cosmetics are emulsions.


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What is a Emulsion?

A emulsion is a meta stable disperse system of

two liquids, which are not soluble in each other.

1.Oil in water (O/W) emulsions and

2. Water in Oil (W/O) emulsions.

The emulsions can be divided up into two groups:



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O/W emulsion

By dispersion of oil into water the oil

drops are the inner, dispersed phase.

Water is the outer, continuous phase.

Cosmetic

removable by water

oil drop

water phase



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W/O Emulsion

By dispersion of water into oil the

water drops are the inner, dispersedphase. Oil is the outer, continuous

phase.

Cosmetic

water resistantWater

Oil



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SKIN CARE

These are used to solve the problems from dry skin to

wrinkles to counteract the effects of ageing.

Lactic acid

swells and soften the top layer of theskin. Also it has some effects in reducing the fine lines

and wrinkles.

Ceramide-3

increases the content within the skinand make it look younger.

Oils Clean and soften the skin. E.g. Natural wool wax

and lanolin.


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Creamsa topical preparation usuallyfor application to the skin



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Cold creams Oil based cleaners. These are

generally semisolid emulsions with water.

Uses

Keep the skin moist and soft.

Vanishing creams oil in water emulsions.

Penetrate the skin without leaving an oily surfacefilm.

Soluble in water and made from fatty acids e.g

stearic acid, oleic acid.

Propylene, glycol, glycerine, sorbitol

incorporated with water phase act to retard

drying out of the creams.


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Foundation creams These are oil soluble

dyes to match the skin color.

Bleaching creams Active ingredients of

ammoniated mercury, sodium perborate.

Emollient creams soften the skin.


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SKIN CARE FOR KIDS

Skin care products for kids usually contain

natural antioxidants , moisturizers ( sweet almond

oil), aloe and milk protein .


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Deodrants and Antiperspirants

Body odour is produced by the breakdown of

the organic fractions of sweat by the natural

skin bacteria.

Deodrants- They merely mask the odour of

sweat rather than seeking to prevent its

formaton.Available in the form of aerolsols, sticks and

gels.


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Deodrants work by

killing the bacteria

and masking the

unpleasant odour

with somethingmore fragrant


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Antiperspirants serve to suppress sweating.

They usually contain anti bacterial agents tohinder growth of odour producing

microorganisms. The contain aluminium salts

in combination with zirconium salts e.g.aluminium chlorohydrate, aluminium

zirconium chlorohydrate etc


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Nail Cosmetics

Nail polishes

Theseconsists of cellulose

nitrate, a plasticizer,

an adhesive resin,dye and a mixture of

solvents.

Nail polish removers

usually consists of

acetone and ethyl

acetate.


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Mouth Cosmetics


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Also called oral cosmetics.

Includes toothpastes and the substances like mouth

washers and sprays that clean the teeth and gums.

Promote a good standard of oral hygiene, which is

essential part of our civilization.

Dentrifices - Dentifrices are agents used along with a

toothbrush to clean and polish natural teeth. They are

supplied in paste, powder, gel or liquid form. Most

common of them is toothpaste.

Toothpaste - Toothpaste is a dentifrice used in

conjunction with a toothbrush to help maintain oral

hygiene.
http://en.wikipedia.org/wiki/Toothbrushhttp://en.wikipedia.org/wiki/Toothbrush


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Common ingredients

Polishing agents e.g. dicalcium phosphate dihydrate.

Foaming agent e.g. sodium lauryl sulphate.

Humectant

Glycerine and sorbitol.

Flavour spearmint, peppermint.


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Uses-

Protect against cavities

Freshens the breath.Reduce tooth senstivity.

Control oral infections.


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Sun Protection

Problems faced:

Sun burns

Skin cancer

Formation of Wrinkles

Ageing.


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Skin care actives fall in two categories-

Inorganic sun blockers These include zinc oxide

or titanium dioxide.

Organic sun absorbers

These includesbenzophenones and octyl methoxycinnamate.

These days both are used in combination.


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Perfumes and Fragrances

Perfumes and Fragrances are all parts of our

daily lives.

Shampoos, soaps, detergents and other

products that we use have fragrancesassociated with them.


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Nose can detect seven

primary odours :

CamphorousMusky

Floral

Pepperminty.

EtheralPungent.

Putrid


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Most of the fragrances

originate from plants.Parts of plants responsible

are

Flower

Seeds (Cardamom)Roots (angelica)

Bark ( Cinnamon)

Peels (Orange).


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The fragrances are extracted from the flowers

in the form of essential oils.

These oils are dissolved in a solvent (ethyl

alcohol).

The percentage of essential oils are

Perfume (20-30%)Cologne ( 8-15%)

Aftershave (1-3%)


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Hair Care

Different products used are:Shampoos

Conditioners

Styling products

Hair dyes


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Hair cleansing

Shampoos are liquid detergents and are

further modified by additives to give

lustre and softness to hair.

These are designed to clean the hair,

which generally equates to removing

grease because the particulate dirt tends

to adhere to the grease rather than thehair itself.


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Major ingredients are : A mixture of Surfactants

ethoxylate and an amphoteric surfactant and

usually an alkanoamide as well.Surfactants are responsible for removing the dirt by

lowering the surface tension. They are also

responsible for the formation of foam.

Some of the foaming agents may also be added e.g

Sodium laryl sulphate.

Then, Coconut fatty acid may be added which

prevent the hair from becoming dry.


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Hair conditioning

The second stage in hair care is conditioning.

Purpose of hair conditioner - To make the hair soft

and shiny and easier to comb.

Earlier it was cationic surfactants like such asstearalkonium chloride was used but these days it is

silicones and proteins often in combination with

cationic surfactants.

Pro-vitamin B5 is most common.


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Hair color

Hair color is modified either byBleaching with Hydrogen peroxide

Colored with hair dyes.

Hair dyes are alkaline solution paraphenylenediammine dyes. These solutions are mixed with

Hydrogen peroxide before being applied to the

hair.

After the color develops the hair are washed away.

Hair darkners are combination of Pb, Ag and Cu

salts with developing solutions.


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Hair Waving

It is the process of changing the shape of the hair.

Two types:

Heat waving- Preparations contain sodium or potassium

sulphite with monoethanolamine, potassium carbonate,ammonium carbonate, sodium borate and water.

These solutions are applied at a temp. of 90-104oC followed

by rinsing with neutralizer which is a dil. Acid.

Cold waving

solution contain ammonium thioglycolate.


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Hairspray

It is a solution of a polymer in a very volatilesolvent.

Spraying deposits a stiff layer of the polymer

on the hair after the solvents evaporates.

Polymers used are polyvinylpyrrolidine, vinyl

acetate and maleic anhydride etc.


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Shaving Creams

Contain water, palmitic acid , stearyl alcohol,

mineral oil, imidazolidinyl urea,

methylparaben, propylparaben and

fragrance.


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Color cosmetics

Most color cosmetics are based on talc whether face

powder, eye shadow or blusher.

Lipsticks : It consists of a solid waxy material mixed

with non volatile oil so that it can spread easily and

also remain stiff in the tube.

Dyes used are insoluble in water so that the color

last longer.

Soluble dyes are converted into insoluble particles

by treatment with metal oxides.


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Eosin is commonly used red dye in lipsticks.

Esters of fatty acids are added to ensure the lipstickhas proper texture, stickness and suitable melting

point.

Natural lipsticks

These contain stain dyes but nopigments and on application develops a pink color.

Oil soluble dyes when used without pigment give

black lipsticks which gives a dark red color.

Mood lipsticks These changes color with diet,

stress, physical activity as these factors affect the


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Rouge

Available in liquid, cream, paste and powder form.

Liquid rouge is formulated as dispersion or a fluid

emulsion containing slow drying or non dryingingredients like glycerine , propylene glycol or

sorbitol.

Cream rouges may be emulsified cream with atexture such that an adequate amount can be picked

by a finger and spread smoothly over the skin.

Solid rouge may be of oil in water or water in oil

chemistry in cosmetics

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