282 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS in which the methyl groups attached to the dimethyl siloxane polymers are partly replaced with organic amine groups. Recently, Wendel and Disapio (5) have shown that ADMS tend to deposit on hair twice as much as dimethiconol and that the ADMS deposited are resistant to cycles of hair wash with shampoo. This measurement was conducted using a technique called electron spectroscopy for chemical analysis (ESCA). In this paper, deposition characteristics were further investigated in greater detail by dividing long hair of approximately 70 cm into three parts, root parts, middle parts, and tip parts, and comparing deposition of ADMS on these parts. Figure 5 shows that the deposition amount on hair was less at the root part, moderate at the middle part, and considerably higher at the tip part. Further, the microscopic distribution of Si-atom on the hair, determined with an electron probe microanalyzer (EPMA) is shown in Figure 6. The result in Figure 6 indicates that ADMS, having stronger affinity to the negatively charged site, are selectively adsorbed on the edges of cuticles of hair. Figure 7 shows the scanning electron microscope (SEM) photograph of cuticle scales and the schematic diagram of the longitudinal slice through the hair surface. Mechanical wearing of the hair surface, caused by brushing, combing, towelling, and other general handling causes the cuticle scale edges to gradually chip away. In Figure 7a, the fractured scale edges and partly exposed endocuticle are shown. Endocuticle contains very little cystine, but, on the other hand, it is rich in acidic and basic amino acid residues, and it swells in contact with water (6). The higher amount of ADMS adsorbed at the hair tip seems to be related to hair surface conditions, which became more hydrophilic due to the damages. By this selective adsorbing characteristic of ADMS, physical properties of the surface of the damaged cuticles are expected to improve with application of ADMS. APPLICATION OF SILICONES IN "2 IN 1" SHAMPOOS PDMS, POES, and ADMS are expected to be especially effective as conditioning agents in "2 in 1" shampoos. The influence of silicones on the foaming properties is shown in Figure 8. A decrease in foam by the addition of PDMS may have resulted from the less A-layer Exoeuticle Endoeuticle A-layer Exoeuticle Endoeutiele Hair surface Fractured scale edge (a) (b) Figure 7. Scanning electron microphotograph of cuticle scales (a), and schematic diagram of the longitu- dinal slice through the hair surface (b).

CONDITIONING AGENTS 283 400 3OO 200 o lOO o B 1 ank PDMS POES ADMS Figure 8. Changes in the foam volume of model shampoos containing 2 wt% silicones. Each shampoo was diluted with 40øC, 4 ø DH water to prepare a 0.5% shampoo solution containing 0.3 wt% model sebum. stable vapor-liquid interface resulting from the formation of PDMS thin films at the water surface. In the case of POES and ADMS systems, on the other hand, these silicones had little effect on the foam volume. Figure 9 shows the measurement of dynamic combing force (DCF) through the shampoo and drying process. This experiment was performed on tufts of hair to which the model "2 in 1" shampoos were applied. For dry conditions, PDMS with high molecular weight was the most effective compared with the other silicones, and this silicone made hair light and extra smooth to the touch. POES with low HLB, which forms liquid crystal in water, were specially effective in reducing combing force while the hair was in contact with running water. By the application of ADMS, which were selectively adsorbed on damaged sites of the hair surface, altering hair surface properties to more hydrophobic conditions, the combing force was retained at a low level throughout the drying process. Consequently, ADMS make hair naturally manageable, eliminating the necessity of blow drying, and they effectively control flyaway of hair tips. In conclusion, use of silicones has enabled formulation of new types of conditioning or "2 in 1" shampoos, and the selection and combination of silicones is of special impor- tance.