58 JOURNAL OF COSMETIC SCIENCE 6O 5O 4O 10 polymer ß 1% gel PQlO PQlO PQlO PQlO Guar Guar (L/H) (M/H)(M/M)(M/L) (H/H) (L/H) Figure 2. 20 ø film gloss of cationic polymers and coacervate gels with SDS. control ionic polymers both with and without surfactant agree very well with the visual assess- ment of the films. OPACITY The opacity of the films on the Leneta charts was examined visually and spectrophoto- metrically. Figure 3 compiles opacity readings of the 1% coacervate gels in comparison with the neat polymer films. Lower opacity readings confirm that polyquaternium-10 and guar (L/H) films are more transparent than guar (H/H), which is consistent with visual inspection. In fact, the wet gel of guar (H/H) presented a yellow haze whereas polyquaternium-10 gels were clear and colorless. The guar (L/H) sample displayed improved color and less haziness than guar (H/H). The coacervate gels followed the same trend as the neat polymer films. Figure 2 also demonstrated that the presence of surfactant in coacervate gels has little impact on the opacity or the clarity of polymer films. Opacity is an important appearance attribute applying to the diffuse rather than to the specular aspect of appearance. Higher opacity readings indicate the stronger power of the polymer hiding a substrate. The film opacity measured by the Hunter Tristimulus colorimeter is inversely related to film transparancy. Figure 3 shows that polyquater- nium-10 and guar (L/H) films give opacity readings similar to that of the control surface, suggesting that the surface beneath the polymer film can be observed. In other words, the polymer deposits on the substrate are invisible. The measurements on guar (H/H) show lower gloss and higher opacity. This combination of the two low gloss and non-transparent films will likely impose a dulling effect when it deposits on hair fibers.

CATIONIC POLYMERS 59 2.0 1.6 0.8 [] polymer ß 1% gel 0.4 0.0 PQ10 PQ10 PQ10 PQ10 Guar Guar (L/I-I) (M/H)(M/M)(M/L) (H/H) (L/I-I) Figure 3. Film opacity of cationic polymers and coacervate gels. control The dulling effect of cationic guar materials on hair has also been reportedly observed in finished conditioning shampoos. COEFFICIENT OF KINETIC FRICTION It has been shown that frictional characteristics of combing materials are of minor importance in hair combing (17). The implication of this result is that hair-on-hair friction is more significant to combing ease than hair-on-comb friction. Therefore, the kinetic friction of polymer on polymer measured in this study can be established to predict the resistance of polymer-coated hairs to sliding or combing. The friction char- acteristics of cationic polymer films can be related to the lubricity of polymer-treated hair. The coefficient of kinetic friction for polymer over polymer at ten-day drying is plotted in Figure 4. Guar (H/H) slides more easily than polyquaternium-10 and guar (L/H) films. The polyquaternium-10 films yielded a higher frictional coefficient than guar (H/H) but similar to guar (L/H). The results suggest that guar (H/H) improves the slip property of treated skin or hair surfaces more effectively. Lower friction of guar (H/H) is attributable to rougher film because friction decreases with increasing film roughness (18). Because rough films in a friction test only contact at high points, lower friction results from a smaller contact area. The frictional properties of the 1% coacervate gels are also included in Figure 4. Interestingly, the incorporation of SDS reduces the friction of polyquaternium-10 samples significantly. The coacervate gels of polyquaternium-10 samples present less friction than the neat polymers. This indicates that SDS lubricates the polymer film by