The use of x-ray fluorescent spectroscopy to study the influence of cationic polymers on silicone oil deposition from shampoo.

In this study, x-ray fluorescent spectroscopy was employed, in a non-destructive way, to analyze the influence that water-soluble, cationic hydroxyethylcellulose (i.e., polyquaternium-10) has on the deposition of silicone oil (dimethicone) onto hair. Virgin brown hair tresses were washed with various model shampoos that contained emulsified dimethicone. The shampoos were modified only by the addition or absence of polyquaternium-10. The results indicate that the cationic polymers do influence silicone oil deposition onto hair during the shampooing process. In the absence of cationic polymer, the silicone oils deposit readily, but appear to show "build-up" phenomena upon repeated washings. When a cationic polymer is present in the continuous phase of the shampoo, the build-up phenomena is significantly diminished, and silicone oil deposition remains relatively constant in repeated washings. In addition, we have noted that the molecular weight of the cationic polymer can have a strong effect on silicone oil deposition. It appears that the higher the molecular weight of the polyquaternium-10, the greater the amount of silicone deposition onto the surface of the hair. To demonstrate that the analysis technique has potential applications in commercial shampoos, we examined a commercial "2-in-1" shampoo that contains dimethicone and polyquaternium-10 and found that the data for our simple model shampoos and the commercial shampoo correlated closely.