HAIR SURFACE CHEMISTRY 73 ---+---3% Peroxide, Neutral pH ---3% Peroxide, pH=9 ---½-----3% Peroxide, Surfactant, pH=9 1.4 1.3 'E 1.2 GI u :ii 1.1 E � 4: 0.9 ,:! :::1 0.8 Cl) 0.7 0.6 0 10 20 30 40 50 Bleaching time, min. Figure 6. Surface oxidized sulfur content after various bleaching treatments. WD=20.5mm Time :9:20:25 Figure 7. SEM image of bleached hair fibers (3% hydrogen peroxide, 45 min., pH = 9, with surfactant).

7 4 JOURNAL OF COSMETIC SCIENCE N(E) Min: 52 Max: 48329 0(1s) C(1s) N(1 s) Si(2s) Si(2p) �-�1L� 602 541.8 481.6 421.4 361.2 301 240.8 180.6 120.4 60.2 -4.57764e-005 Binding Energy (eV) Figure 8. Surface elemental "survey" scan showing the composition of conditioner-treated hair. Element C N 0 s Si Ca Table III Surface Composition of Conditioner-Treated and Bleached Hair Bleached sample 73.2 7.7 15.9 1.9 0.5 0.8 Treated sample 64.8 2.0 19.0 1.5 12.5 0.1 and ester quat. The changes in the C(ls) spectrum indicate the presence of a predomi­ nantly hydrocarbon like layer at the surface, which in this case is due to the methyl groups of the dimethicone and the long change fatty acid esters in the ester quat (Figure 9). High-resolution spectra from the treated surface confirm the presence of the ester quat by the unique R4N + chemical state of nitrogen. The relatively high oxygen content of the ester quat (-9 atom% oxygen) and especially the dimethicone (-23 atom% oxygen) are responsible for increasing the observed oxygen content on the treated hair surface. No evidence for retained chloride (Cl-) from the original salt of the quaternary amine was observed. The absence of the anionic chloride at the surface indicates the solvated chloride did not interact with the hair surface, (hair surface possesses a net negative charge at neutral pH, IEP = 3.7) and was washed away with the rinse. In addition, the absence of negatively charged counter ion indicates that multilayer formation of the quat