Functional Ultraviolet Absorbers in Hair CareMany consumer shampoos with traditional UV absorbers are currently marketedaround the world. These shampoos claim UV protection for hair. It is generallyrecognized that because of their water insolubility, these traditional UV absorbersare not readily deposited onto the hair during shampooing. Because shampoo formulationsare different from sun-screen formulations, these molecules are reallynot suitable for shampoo applications. To improve the substantivity of UVabsorbers, quaternary ammonium functionality has been combined with UV filtersin a single molecule. Two excellent examples follow.Dimethylpabamidopropyl Laurdimonium Tosylate B. The damage causedto hair by ultraviolet radiation is well known. Tryptophan degradation, cystineresidue reduction (weakening the strength of the hair), and changes of the cuticleall are recognizable as damage induced by UV light [10–13]. Althoughcommercially available sunscreens are able to protect against UV-A and UV-Blight, they are not functionally suitable for hair care. In cleansing formulations,typical sunscreens are not substantive toward hair. It is not difficult to realize thatthey were not designed for rinse-off applications. In conditioning formulations,these ingredients are water insoluble and also lack substantivity.The degree of sun damage to hair tresses was indirectly measured through astaining method with a Hunter Lab Colorimeter. Comparison of treated anduntreated hair tresses using thiol-indicating Merbromin stain demonstrated significantprotection of the hair shaft with dimethylpabamidopropyl laurdimoniumtosylate (as Escarol HP-610 from ISP) [19]. Approximately a 50% improvementwas measured [14]. In an additional study measuring the photoprotection of tryptophana 25% increase in tryptophan stability was measured by means of fluorescencespectroscopy [14,15]. To further demonstrate the protection offered by42 DalrympleFIGURE 7 Cinnamidopropyltrimonium chloride.FIGURE 6 Coming force measurements.dimethylpabamidopropyl laurdimonium tosylate, a combing test was performedwith a Diastron Miniature Tensile Tester. Three standard sunscreens (octylmethoxycinnamate, DEA methoxycinnamate and benzophenone-3) were comparedwith dimethylpabamidopropyl laurdimonium tosylate. The test productswere applied to damaged hair as solutions. After rinsing, the hair tresses were irradiatedfor 72 h. The tresses were then shampooed to eliminate any surface treatmenteffects. Comparative measurements were then taken. The results are given inFig. 6. The surface damage was reduced for the sample treated with dimethylpabamidopropyllaurdimonium tosylate.Cinnamidopropyltrimethylammonium Chloride C. Cinnamidopropyltrimoniumchloride was introduced to the hair care market in 1998 (Fig. 7). CinnamiMultifunctionalHair Care Products 43dopropyltrimonium chloride has a molar extinction coefficient of 21,605 cm2/molat 280 nm1 [16]. It is a liquid at room temperature and easy to process. Because sunscreensvary in their water solubility they often are diluted by perspiration. Consistentreapplication of sunscreen is often needed. Another obstacle to overcome is theneed to provide substantivity without overloading the hair shaft. Preparation of sunscreenformulations employing hydrophobic carriers may result in a product havingunfavorable properties such as a greasy feel. This is a particular problem for formulationfor hair care and protection. Cinnamidopropyltrimonium chloride is anamidoquaternary that is water soluble yet at the same time highly substantivetoward hair. To demonstrate the deposition of the cationic onto hair, a standardrubine dye test was conducted using bleached hair. A 2% w/w active aqueous solutionwas compared to a blank of deionized (DI) water. This standard techniquegave a positive response to the hair tresses with cinnamidopropyltrimonium chloride[16].It has been shown that cinnamidopropyltrimonium chloride is able to protect

blonde hair from damage by UV radiation. Two simple cleansing base formulationswere compared. Both contained 10% SLS. One contained 2% octylmethoxycinnamate (an approved sunscreen in the United States) and the other, 2%cinnamidopropyltrimonium chloride. Bleached blonde hair tresses were treatedwith both formulations and then subjected to light in the UV-B range. A thirduntreated hair tress was also subjected to UV-B light. A fourth hair tress, used asa positive control, was not subjected to UV-B radiation. The results clearly showeda degradation of color for the untreated hair tress and the hair tress treated withoctyl methoxycinnamate solution. The hair tress treated with cinnamidopropyltrimoniumchloride and the hair tress not subjected to UV-B light were virtuallyidentical [17].