ToF-SIMS characterization of the lipid layer on the hair surface. II : Effect of the 18-MEA lipid layer on surface hydrophobicity

In this study, the effect of the damage level of 18‐MEA on the hydrophobicity of hair surfaces and the mechanism of technology for replenishment of the lipid on damaged hair surfaces were examined using Time‐of‐Flight Secondary Ion Mass Spectrometry (ToF‐SIMS). The surface amount of 18‐MEA was measured in Japanese women by ToF‐SIMS. It was obvious that the 18‐MEA was decreased drastically by coloring treatments, especially in individuals who underwent such treatments more than two times per year. Additionally, even in hair without any chemical treatments, more than 80 percent of 18‐MEA was removed at the portion 40 cm from the hair root. The relationship between the surface contact angle of the hair fiber and the 18‐MEA amount showed that 18‐MEA played an important role in surface hydrophobicity. It was found that, as a replenishment technology of the surface lipid layer, 18‐MEA conditioner treatment combined with a specific cationic surfactant (Stearoxypropyldimethylamine: SPDA) effectively results in persistent hydrophobicity and low friction on damaged hair surfaces. ToF‐SIMS analyses revealed that the homogeneous adsorption layer provided by 18‐MEA/SPDA treatment resulted in effective hydrophobicity in damaged hair. Copyright © 2010 John Wiley & Sons, Ltd.