What are hydrogen bonds in hair primarily affected by?

Hydrogen bonds in hair are primarily affected by water and thermal heat because these two factors directly influence the structure and behavior of the hair's keratin proteins.

When hair is wet, water molecules form hydrogen bonds with the keratin, which can temporarily change the shape and elasticity of the hair. This is why wet hair can be easily styled or manipulated; the hydrogen bonds are disrupted, allowing the hair to be reshaped. Upon drying, the hydrogen bonds reform, thus setting the hair in its new shape.

Thermal heat also plays a crucial role in affecting hydrogen bonds. When heat is applied, it can weaken or break these bonds, making it easier to alter the hair's texture or shape. For example, using a curling iron or straightener allows the stylist to transform the hair’s appearance by temporarily breaking and reforming these bonds with heat.

While chemicals, physical stress, and oils can influence hair in various ways, they do not directly impact hydrogen bonds in the same manner as water and heat. Instead, chemicals may alter the hair's structure through different types of bonds, and physical stress can lead to hair damage, while oils mainly serve to condition and lubricate the hair without directly affecting hydrogen bonding. Therefore, water and thermal heat are the