240 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table VI Designed Experiment: Polyquaternium-10 Treated Samples Atomic % Sample C N Tress End CH C - O C = O Amide N + O S•/S2 B Root 53.8 15.6 6.4 4.4 0.4 16.2 1.89 B Tip 49.5 21.8 4.6 3.1 0.8 17.4 0.85 B Root 53.2 15.8 8.5 4.4 0.5 14.3 2.02 B Tip 50.9 18.1 7.2 3.3 0.8 17.1 0.77 C Root 53.5 15.6 7.1 3.4 0.6 16.4 1.36 C Tip 50.9 18.3 6.8 3.7 0.9 15.4 0.86 in the elemental compositions and in the high-resolution data. Relative standard devia- tions are less than or equal to 10% for all but the tip end of sample B and compare favorably with those established for control hair previously (Tables I and II). These particular samples generally show somewhat higher oxygen content than the initial control samples, as evidenced by slightly higher levels of C- O-type carbon. In general, there are few distinct compositional differences noted between these samples, either from tress-to-tress or root-versus-tip regions from the same tress. (The exception is the D tress pairs which do exhibit a statistically significant increase in oxygen content for the tip end versus the root end.) The one definite trend observed is the change in the relative amounts of the two forms of sulfur detected. The root end of the hair fiber shows a majority of sulfur present as the low-binding-energy disulfide form. However, upon moving to the tip ends of the hair, the higher-binding-energy sulfonate or thiosulfonate form begins to predominate. This shift is illustrated in Figure 4 and is in agreement with other studies reported in the literature (3,4). This change has been attributed to oxidation of the sulfur as part of the aging or weathering process in hair. Sample B exhibits several anomalies, the most obvious of which is the presence of Table VII Designed Experiment: Samples Treated With Polyquaternium-24 Atomic % Sample C N Tress End CH C - O C = O Amide N + O S•/S2 A Root 34.1 27.5 3.2 2.4 0.6 28.8 1.44 A Tip 49.4 23.3 4.1 1.6 0.5 19.1 0.53 C Root 35.7 30.4 6.1 1.6 0.7 24.0 0.90 C Tip 36.2 33.4 3.7 1.4 0.7 23.3 0.43 D Root 40.1 24.5 8.5 2.7 0.4 20.5 2.02 D Tip 44.4 24.7 4.4 2.0 0.5 21.4 0.69 D Root 53.2 20.2 5.4 2.4 0.3 15.7 1.19 D Tip 48.3 21.0 5.3 3.4 0.4 19.1 0.95

ESCA OF POLYMERS ON HAIR 241 DISULFIDE ROOT E N D • 178,5 158.5 BINDING ENERGY (eV) Figure 4. Sulfur high-resolution spectrum of tip-versus-root ends of hair. quaternary nitrogen in high quantities on the tip end. The source of this component is unknown however, it suggests that contamination by quaternary ammonium-con- taining material is the source of the scatter observed in the data for this particular sample. (Note that a small quantity of NR4 + was also observed on the tip half of sample A). Occasional contamination is not surprising in view of the source and nature of the substrate. POLYMER-TREATED SAMPLES Polymer deposition is again readily detected. However, examination of the Polyquater- nium-10 data reveals very interesting substantivity behavior. The surface composition data (Table VI) reveal generally higher oxygen and lower nitrogen contents on the tip end samples (except for specimen C). These observations suggest preferential polymer adsorption at the tip ends. This conclusion is confirmed upon inspection of the high- resolution data which in all cases show higher levels of cellulosic type carbon (C- O type) and greater amounts of quaternary nitrogen on the tip ends as opposed to the corresponding root ends. This differential adsorption behavior is very interesting. A contribution to the observed behavior is probably the greater availability of ionic attachment sites on the tip end. As previously discussed, the sulfur present on the hair fiber exists in two forms. Of these, the sulfonate type provides anionic sites which are capable of binding the cationic polymer. With increasing thiosulfonate and sulfonate at the tip ends (note S 1/S2 ratio in Table VI), a higher degree of adsorption occurs. Another factor likely to cause an