Deposition of 18-MEA onto alkaline-color-treated weathered hair to form a persistent hydrophobicity

• Published in: International journal of cosmetic science Vol. 32; no. 1; pp. 82 - 83
• Main Authors: Tanamachi, H., Inoue, S., Tanji, N., Tsujimura, H., Oguri, M., Ishita, M., Tokunaga, S., Sazanami, F.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-02-2010
• ISSN: 0142-5463; 1468-2494
• DOI: 10.1111/j.1468-2494.2009.00533_5.x

J. Cosmet. Sci., 60, 31–44 (January/February 2009)
Synopsis
A technology for the deposition of a persistent hydrophobicity to alkaline‐color‐treated weathered hair surfaces using 18‐MEA (18‐methyleicosanoic acid) is presented. Two approaches were examined in order to make 18‐MEA bind tightly to the alkaline‐color‐treated weathered hair surface. One was to apply 18‐MEA as an acid form and the other was to apply 18‐MEA as a salt or complex. It was found that the combination of 18‐MEA with specific cationic surfactants [stearoxypropyldimethylamine (SPDA) and docosyldimethylamine (DSDA)] makes the alkaline‐color‐treated weathered hair surface hydrophobic and that its hydrophobicity is maintained even after shampooing. Characterization of adsorbed layers of 18‐MEA/SPDA on a mica surface, as a possible hydrophilic surface model, was performed using atomic force microscopy (AFM) and angle‐resolved X‐ray photoelectron spectroscopy (AR‐XPS). The results revealed that 18‐MEA/SPDA formed a layer with high wear resistance, with an alkyl chain, the hydrophobic moiety, oriented at an angle of around 25° to the air interface.