Friend: tiahu (4200 + approved, recommended by Zhihu editor)
Too long to read:
1. Does silicone oil block pores? - no
2. Does silicone oil affect cleaning power? - no
3. Should shampoo and conditioner be separated? -If possible, it is recommended to separate them. Because there is a little conflict between the action of anionic surfactant and cationic surfactant. But if we dont separate, it doesnt hurt.
Silicone free shampoo is just hype. If you want to believe it, you can believe it. Its just like a pregnant womans radiation proof clothing. Please like it. (btw, I dont believe in radiation proof clothing, but my wife still has to buy it when she is pregnant
It has been mentioned that silicone oil is the substance that makes hair smooth. In fact, there are some misunderstandings.
Next, it is explained in several aspects:
1. Cleaning ability of shampoo
Our hair is exposed to the natural environment, and gradually becomes more and more dirty. This dirty, mainly is the oil secreted by the scalp, peeling off scalp debris, dust in the environment and so on gradually accumulated. Because the oil is insoluble in water, it is not very effective to wash it with water.
So the first basic ingredient in shampoo is anionic surfactant, which is used to remove oil.
However, if there are only anionic surfactants in shampoo, there are usually two consequences:
(1) too strong decontamination;
(2) pH is too high.
Both of these conditions can lead to rough hair. The reasons are explained in the next paragraph.
2. Basic structure of hair fiber
The structure of hair scale on the surface of hair fiber is mainly composed of keratin.
Keratin molecule, is a long chain, usually curly structure, can be imagined as an entangled rubber band. The force that curls this chain comes from intramolecular and intermolecular hydrogen bonds, as well as disulfide (- S-S -).
Keratin spiral structure (picture from network, invasion and deletion)
These bonds are not very strong. Hydrogen bonds can be easily opened in the presence of water, especially in the alkaline environment (with high pH).
Therefore, if you get up in the morning and your hair is messy, dip some water in it to comb your hair, you will press down the curled hair. This is because water destroys the hydrogen bond of hair and makes curly hair lose its elasticity.
Imagine the effect of opening the winding rubber band. When the hair is dry, the hydrogen bond is formed again, and it is fixed in the shape after combing. In a word, the principle of straightening and hot rolling is similar to this, except that the disulfide bond needs to be opened.
It is for this reason that washing your hair with washing powder (in other words, I used to do this in College) or soap, because of the strong alkalinity of washing powder and soap, will lead to the full opening of hair scales, so that after washing, the hair is completely dry, astringent and fluffy.
Because of the characteristics of hair surface structure and keratin, if the hair scales on the hair surface are damaged, a negative charge will be formed at the gap.
The lipophilic end of the cationic surfactant is positively charged and therefore fills these gaps, resulting in:
(1) the surface of hair fiber was repaired;
In appearance, it is to make the hair no longer rough.
In hair conditioner, cationic surfactant is used to repair hair damage. In addition, cationic surfactants are sometimes used in fabric softeners, in fact, the same is true.
However, cationic surfactants and anionic surfactants in shampoo will react and conflict with each other, resulting in precipitation. Therefore, shampoo with hair care function, usually slightly adjust the formula, use some non-ionic surfactants.
4. Function of silicone oil
If you are familiar with cosmetic raw materials, you should know that the main functions of silicone oil are:
(1) moisturize and soften the skin, providing a light skin feeling.
(2) film forming.
Skin feeling is due to the small molecular weight of silicone oil, low viscosity, strong penetration, so it is widely used in skin care products.
Because of its ability to lock water, it is also used in wound care and other ways.
However, the membrane formed by silicone oil has porous structure. Its not clogging the pores, as some people assume.
At present, there is no published research that can confirm that silicone oil can cause any form of acne aggravation, skin irritation or suffocation.
I think that should be enough.
Appendix: 1. Recommended reading: haircondition Wikipedias entry on conditioner 2. Cosmetics ingredient Dictionary: silicone cosmetics innovation Dictionary: cosmetics copexpert advice 3. Recommended reading: siliconeoil Wikipedias entry on silicone 4. References: Schlossman m. The Chemistry and manufacturing of cosmetics. Carolstream: alluredpublishing Corp; 2002.p.833-8 Thirty-nine