Adsorption properties of amphiphilic polyoxyalkylenated dimethylpolysiloxane derivatives on keratin

Adsorption properties of two types of dimethylpolysiloxane backbone derivatives, perfluoroalkyl polyoxyethylenated dimethylpolysiloxane (FPD) and polyoxyethylenated dimethylpolysiloxane (PD), onto keratin surfaces were investigated. Both polymers are amphiphilic, since they possess hydrophilic polyoxyethylene groups. FPD contains a perfluoroalkyl group that provides both water- and oil-repellent properties, whereas PD lacks these groups. Adsorption properties of these polymers onto keratin surfaces are considered a good index to evaluate these compounds as nonionics used in hair-coating agents, since keratin is a major component of hair. FPD was more likely to be adsorbed and less likely to be eliminated from the keratin surface than PD. Once FPD had been adsorbed onto the keratin surface, it was very slowly washed from the surface when it was immersed in stationary water, whereas PD polymers were quickly washed from the keratin surface. Even in running water, rapid elimination of FPD was not observed. The strong resistance to loss of FPD after washing with a large quantity of water may be due to the water-repellent nature of the perfluoroalkyl groups. As a comparison, FPD adsorption onto a glass surface was also investigated. The affinity to the glass surface was found to be less than to the keratin surface.