Mechanism of Bio IOS's Surface Activity and Water Solubility Elucidated, Paving the Way for Broader Applications of Sustainable Surfactants

To continuously support people's enriched life, it is essential to secure sustainable sources of surfactants, which are the main ingredients of detergents. While surfactants are known to have a molecular structure consisting of a lipophilic group (alkyl chain), which has a strong affinity for oil, and a hydrophilic group, which has a strong affinity for water, surfactants in general use today typically have an alkyl chain length of 12 to 14 (C12 to C14) and are made from only 5% of all vegetable oil, so their long-term supply has become a pressing issue.
In 2019, Kao developed Bio IOS (Figure 1), a novel surfactant with a longer alkyl chain (C16 to C18) that has a hydrophilic group located at the middle of the chain^*2 . Bio IOS is considered to be a sustainable compound because it is made from the solid fraction of palm oil that is not consumed as food so much and has limited applications.

Regarding the basic properties of surfactants, it is important that they possess both high surface activity (affinity for both water and oil) and high water solubility (easy to dissolve in water). If a surfactant has high surface activity, only a small amount is needed to perform a given cleansing task, so its total usage can be reduced. In addition, if it is highly soluble in cold and hard water, it can be used virtually anywhere around the world.
Kao believes that demand will continue to rise in the future for this type of sustainable surfactant that not only uses sustainable materials and is less harmful to the natural environment but also possesses both high surface activity that allows consumers to enjoy the same level of cleansing performances as well as high water solubility so that it can be used anywhere in the world. This is why Kao has been conducting research on the essential workings of surfactants while harnessing the full potential of its proprietary Bio IOS, with the ultimate goal of broadening the application of sustainable surfactants and improving their utility.

Generally, as the alkyl chain length of a surfactant increases, its surface activity rises but water solubility declines. Conversely, as its alkyl chain length decreases, its water solubility improves but surface activity decreases. Due to this tradeoff, it has been difficult to develop a surfactant that maintains both high surface activity and water solubility. However, Bio IOS has been proven to possess high water solubility as well as excellent surface activity due to its long alkyl chain (Figure 2).
To investigate the mechanism of these characteristics, Kao's researchers analyzed Bio IOS's conformation in water^*3 to test the hypothesis that its spatial molecular structure in water, where detergents are normally used, might differ from that of conventional surfactants.

Kao has been marketing its concentrated-liquid laundry detergent Attack ZERO which contains this sustainable surfactant Bio IOS as one of the ingredients. Kao remains committed to conducting research on fundamental technology to continuously build essential knowledge on natural phenomena and to developing products that are truly friendly to both humans and earth, so that people can enrich daily living for generations to come.

Kao creates high-value-added products and services that provide care and enrichment for the life of all people and the planet. Through its portfolio of over 20 leading brands such as Attack, Bioré, Goldwell, Jergens, John Frieda, Kanebo, Laurier, Merries, and Molton Brown, Kao is part of the everyday lives of people in Asia, Oceania, North America, and Europe. Combined with its chemical business, which contributes to a wide range of industries, Kao generates about 1,420 billion yen in annual sales. Kao employs about 33,500 people worldwide and has 135 years of history in innovation. Please visit the Kao Group website for updated information.