280 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS films of hair surface, is more effective than cationic surfactants in improving the surface characteristics of hair. Figure 3 shows the amount of PDMS deposited on hair surface and the effect on }x k. The }x k values were found to be depressed when the amount as Si deposited exceeded approximately 100 •zg/g hair. This result may suggest that the amount of PDMS sufficient to form the film, which persists on the hair surface under the mechanical friction, is probably more than 100 •zg/g hair. DIMETHICONE COPOLYOLS (SILICONE GLYCOL COPOLYMERS) With dimethicone copolyols (POES), some methyl groups attached to silicon have been replaced by polyether side chains, namely ethylene oxide or propylene oxide polymers or the copolymer of these. Since most POES contain enough glycol to be water-soluble, they are particularly useful in shampoo formulations requiring clarity. The chemical structures, the HLB values calculated, water solubility, and surface tension of various POES are listed in Table II. POES with lower HLB values are not water-soluble, and in this sense they become similar to PDMS. With the addition of polyoxyethylene units and the reduction of 100 8O 60 40 20 ......................... -- iiiiiiiiiiiiiiiiiiiiiiiil ......................... ::::::::::::::::::::::::: ::::::::::::::::::::::::: ::::::::::::::::::::::::: ::::::::::::::::::::::::: .................................................. ::::::::::::::::::::::::: ::::::::::::::::::::::::: :::::::::::::::::::::::: ::::::::::::::::::::::::: :::::::::::::::::::::::: ::::::::::::::::::::::::: ::::::::::::::::::::::::: ::::::::::::::::::::::::: ::::::::::::::::::::::::: :::::::::::::::::::::::: ................................................. ................................................. ::::::::::::::::::::::::: :::::::::::::::::::::::: :::::::::::::::::::::::::: :::::::::::::::::::::::: :::::::::::::::::::::::::: ::::::::::::::::::::::::: :::::::::::::::::::::::::: ::::::::::::::::::::::::: ::::::::::::::::::::::::: :::::::::::::::::::::::::: ::::::::::::::::::::::::: :::::::::::::::::::::::::: :::::::::::::::::::::::::: ::::::::::::::::::::::::: :::::::::::::::::::::::::: :::::::::::::::::::::::::: ::::::::::::::::::::::::: :::::::::::::::::::::::::: :::::::::::::::::::::::::: ::::::::::::::::::::::::: :::::::::::::::::::::::::: :::::::::::::::::::::::::: ::::::::::::::::::::::::: :::::::::::::::::::::::::: :::::::::::::::::::::::::: ::::::::::::::::::::::::: :::::::::::::::::::::::::: ::::::::::::::::::::::::: :::::::::::::::::::::::::: .......................... ::::::::::::::::::::::::: :::::::::::::::::::::::::: :::::::::::::::::::::::::: ::::::::::::::::::::::::: :::::::::::::::::::::::::: :::::::::::::::::::::::::: ::::::::::::::::::::::::: :::::::::::::::::::::::::: :::::::::::::::::::::::::: ::::::::::::::::::::::::: :::::::::::::::::::::::::: :::::::::::::::::::::::::: ::::::::::::::::::::::::: :::::::::::::::::::::::::: :::::::::::::::::::::::::: ::::::::::::::::::::::::: :::::::::::::::::::::::::: :::::::::::::::::::::::::: ::::::::::::::::::::::::: :::::::::::::::::::::::::: :::::::::::::::::::::::::: ::::::::::::::::::::::::: :::::::::::::::::::::::::: :::::::::::::::::::::::::: ::::::::::::::::::::::::: :::::::::::::::::::::::::: :::::::::::::::::::::::::: ::::::::::::::::::::::::: :::::::::::::::::::::::::: .......................................................................... :::::::::::::::::::::::::: ::::::::::::::::::::::::: ::::::::::::::::::::::::: :::::::::::::::::::::::::: ::::::::::::::::::::::::: ::::::::::::::::::::::::: :::::::::::::::::::::::::: ::::::::::::::::::::::::: ::::::::::::::::::::::::: :::::::::::::::::::::::::: ::::::::::::::::::::::::: ::::::::::::::::::::::::: :::::::::::::::::::::::::: ::::::::::::::::::::::::: ::::::::::::::::::::::::: :::::::::::::::::::::::::: ::::::::::::::::::::::::: ::::::::::::::::::::::::: ::::::::::::::::::::::::: ::::::::::::::::::::::::: ::::::::::::::::::::::::: ......................................................................... .......................................... ............................ Root liddle Tip Figure 5. Effects of hair parts on amount of ADMS deposition, treated with model shampoo containing 0.2 wt% ADMS.

CONDITIONING AGENTS 281 dimethylsiloxane units, both increasing the HLB values, these POES become dispersible and then finally water-soluble. In the case of the solution of POES with HLB values ranging from 5 to 6, liquid crystal formation was observed with a cross-polarizing microscope. With ordinary nonionic surfactants with polyoxyethylene chains, aqueous solutions are known to form lyotropic liquid crystals at optimum HLB (4). This solution behavior of POES bears fundamental similarity to that of organic surfactants, with the hydrophobic hydrocarbon groups being replaced by hydrophobic dimethylsiloxane groups. The amount of POES deposition on hair treated with the model shampoo, containing 4 wt% POES, is plotted in relation to the HLB values in Figure 4. The samples with higher HLB scarcely remained on hair after being rinsed with water, and this is because of their high hydrophilicity. However, the samples of POES with lower HLB, dispersed in water, behaved almost identically to the PDMS as far as the amount of deposition is concerned. This result implies that the hydrophobic interaction between dimethylsi- loxane units and hair surface plays an important role in the sorption behavior of silicones on hair. Therefore, the POES containing sufficient polyoxyethylene units to be water- soluble provide only a subtle conditioning effect, while POES with low HLB provide a light conditioning effect because of their deposition properties. AMODIMETHICONE (AMINOFUNCTIONAL SILICONES) One of the newest groups of silicones is the aminofunctional silicone polymers (ADMS), Figure 6. The distribution of Si atom on the hair surface by EPMA (line analysis). The hair sample was treated with 0.2 wt% ADMS emulsion.