Its main feature is its extremely high moisturizing and hydrating property. However, because sodium hyaluronic acid contains hydroxyl functional groups and is negatively charged, the surface of human skin and hair also has negative charges. Since they are both negatively charged, unmodified sodium hyaluronic acid is not easily adsorbed by the human skin and hair. After being rinsed with water, most of the sodium hyaluronic acid is washed away, resulting in a poor moisturizing effect and failing to achieve good moisturizing results.