60 JOURNAL OF COSMETIC SCIENCE 0.30 ß - 0.20 = 0.10 .[3 polymer ß 1% gel 0.00 PQlO PQlO PQlO PQlO Guar Guar (L/H) (M/H) (M/M) (M/L) (H/H) (L/H) Figure 4. Coefficient of kinetic friction of cationic polymers and coacervate gels. possibly lowering surface tension. Figure 5 shows that the slip property of guar (L/H) is compromised although it offers better film clarity and gloss compared to guar (H/H). Also, in the presence of SDS, polyquaternium-10 exhibits comparable or even lower friction than the guar (H/H) coacervate. All in all, polyquaternium-10 renders high film gloss and clarity, as well as beneficial lubricity when delivered from surfactant systems. SURFACE PROFILE OF POLYMER FILMS The SEM micrographs of cationic polymer films are presented in Figure 5 (a, b, c), with the measurement bar representing 1 pro. The bright spots (domains) reflect surface textures of the films. The number and size of the "domains" in the SEM images represent the macro effect of surface roughness. Fewer such domains are present in the polyquater- nium-10 (H/H), signifying a smooth, shiny film. Guar (H/H) displays significantly larger domains that reduce gloss of the polymer film. The domains are smaller in size and more uniformly distributed in guar (L/H) than in guar (H/H). This accounts for the gloss and friction increase of this guar sample. However, tremendous film texture is still responsible for its lower gloss compared to polyquaternium-10 samples. The film difference between the two classes of cationic polymers was also confirmed by atomic force microscopy (AFM). The topographic AFM images illustrate the three- dimensional surface roughness. The surface topology of two medium-molecular-weight polyquaternium-10 samples with high and low charges are shown in Figure 6 and 7. Both polymer drawdown films appear relatively smooth, supportive of their high gloss values. Figure 8 and 9 are the AFM topographic images of two cationic guar films. The

CATIONIC POLYMERS 61 Figure 5. SEM micrographs of polyquarternium-10 and cationic cationic guar films. a. PQ-10 (M/H). b. Guar (H/H). c. Guar (L/H).