Originally Posted by patrickBOOTH
I've done a fair amount of researching the chemistry behind shampoos, conditioners, and other styling products. It is very interesting stuff. All of the hate of detergents, or certain surfactants in shampoos are largely unfounded. Below I will disclose, at its most basic level the different ingredients in shampoos and conditioners, which make them effective.
The active ingredients in shampoo is some form of detergent to emulsify oil and dirt so it can be washed away from the hair. The anti-sulphate phenomenon is responsible for shunning of Sodium laureth sulfate, or "SLES". Sulphates are used in shampoos not because they are cheaper, or any of those evil rumors that you hear of, but rather because they are extremely effective. Some people have certain reactions to them if they are not rinsed well and remain on the skin, but from what I understand those people are few and far between. All detergents are not made equally, however. An example of a less "harsh" detergent would be sodium lauryl sulfate, or "SLS". Some supposedly "sulphate free" detergents might include sodium cocoyl sulfate, which is used to trick folks who don't like to see the words "laurel", or "laureth" in their shampoo, but it is very, very similar to sodium lauryl sulphate.
Some other premium detergents that are very mild for hair include Sodium Lauroyl Methyl Isethionate, Dosodium Laureth Sulfosuccinate, and Sodium Laurel Sarcosinate and sodium isethionate.
Along with the detergent in shampoos there will be a melange of other conditioners that deposit on the hair. These conditioners can be silicones, proteins, or Polyquaterniums. Silicones are meant to coat the hair and offer shine, protection, manageability. Most silicones are non-polar and hydrophobic, meaning they don't have an electrical charge and they repel water. They are generally suspended in an emulsion that when you rinse your hair the silicone gets deposited on the hair shaft and repels the water (because it is hydrophobic) this is called "dilution deposition".
Some silicones can be formulated with a charge that sticks to hair, however. The silicones that have a change, like the polyquaterniums work well as conditioners because they carry a positive electrical charge that is attracted to the hair's negative electrical charge. When in the presence of each other they hydrogen bond together. Damaged parts of the hair that has some of the hair's core exposed are even more negatively charged than the cuticle so these types of conditioners do a great job of attracting themselves to the hair and providing slip, and anti-static properties.
Examples of some silicones include, Amodimethicone, Dimethicone, Dimethiconol, Cyclopentasiloxane.
Examples of cationic conditioners include: Polyquaterniums, Benentrimonium Chloride, Cetrimonium Chloride
Generally, Polyquaterniums will have a number after it. The number is only the order in which it was formulated so it doesn't tell you anything about its behavior, unfortunately. All Polyquaterniums have slightly different properties.
If anybody has any direct questions about product ingredients I think I could be a good resource as I have developed a keen interest in cosmetic chemistry.