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J. Cosmet. Sci., 60, 217–238 (March/April 2009) 217 Protection of oxidative hair color fading from shampoo washing by hydrophobically modifi ed cationic polymers Y. ZHOU, L. FOLTIS, D. J. MOORE, and R. RIGOLETTO, International Specialty Products, 1361 Alps Road, Wayne, N.J. 07470. Synopsis The fading of oxidative color in hair as a result of daily shampoo washing activities has become a com- mon problem and a source of frequent complaints by consumers. The fading occurs primarily through hair dye solubility in water. One aspect of the current study investigates the physical and chemical fac- tors that infl uence hair color fading during the washing process. This is accomplished by testing hair dye dissolution in water from dyed hair samples with variation of surfactant type, pH, and hair type. Furthermore, a new approach to preventing color fading is developed aiming to provide an effective barrier function for hair dye from dissolving into water. The preliminary investigation of a series of polymers with various functional groups indicates that polymers with hydrophobically modifi ed and cationic functionalities are most effective in preventing hair dye dissolution in water. It is also evident that a synergistic effect of the polymer’s hydrophobic moieties and cationic charges are important on hair color protection during shampoo washing processes. A primary example of a polymer within this category is a cationic terpolymer of vinylpyrrolidone, dimethylaminopropyl methacrylamide, and meth- acryloylaminopropyl lauryldimonium chloride (INCI: Polyquaternium-55). The color protection bene- fi t of this polymer is evaluated using newly developed methodologies for evaluating hair color changes, such as hair color fading tests through multiple shampoo washes with mannequin heads and hair tresses, both derived from human hair, colorimetry, and quantitative digital image analysis. In addition, new infrared spectroscopic imaging techniques are used to detect the hair dye deposition behavior inside hair fi bers both with and without the color protection treatment. Both visual and instrumental measurement results indicate that Polyquaternium-55 provides a high level of color protection when formulated in a hair color protection regimen with up to 50% color protection. This regimen signifi cantly outperforms commercial products that were tested containing a color protection claim. The proposed mechanism for the anti-fading action of hydrophobically modifi ed polymers includes a cationic charge-reinforced hy- drophobic barrier. This model is supported by evaluating the color fastness effect of several different polymer chemistries and by measuring hair surface hydrophobicity changes. INTRODUCTION Coloring hair becomes increasingly popular year to year. However, fading of artifi cial hair color has become a common problem and a source of frequent complaint by consumers. Lush, colorful hair begins to look dull with a loss of vibrancy and intensity, yielding a shade shift deemed non-desirable after a couple of weeks before roots grow out. The loss of dye hair color typically occurs because of color wash-out during the daily shampooing process or can be initiated by environmental circumstances such as exposure to UV radia- tion which can break down the color molecule. It was found that the washing process is