426 JOURNAL OF COSMETIC SCIENCE ._ 2000 "iii tn 1500 E 1000 I! tn e soo ·e 0.07wt.% 0.15wt.% 0.25wt.% Cationic guar PQ-67, PQ-67, %N-2.1, %N-2.5, Medium HS Medium HS I II Cat. guar II PQ-67, Medium HS ■ PQ-67, High HS I I□ 1 wt.%silicone II 0.3 wt.%silicone I Figure 3. Silicone deposition on European virgin brown hair: formulations with fractional amounts of PQ-67 polymer or silicone. A. Formulations with 0.007 to 0.25 wt.% Polymer and 1 wt. % Silicone. B. Formulations with 0.25 wt.% Polymer and 0.3 to 1 wt.% Silicone. Further studies revealed that even minimal amount of hydrophobe, such as, for example, the low level hydrophobic substitution present in the commercial products SoftCAT SL-5, SK-M, and SK-H, was sufficient to observe the significant boost in silicone deposition between PQ-10 and PQ-67 polymers. At the same time, varying HS in polymers with the CS corresponding to 1.0-1.8 wt.% N did not result in significant changes in silicone deposition. As discussed earlier and according to the data presented on Figure 2A, the prototype benchmark Formulation A prepared with cationic guar deposited significantly more silicone (~675 microgram silicone per gram of hair) on virgin brown hair compared to either group of cationic cellulosic polymers. In order to close this gap, we focused on the PQ-67 structures with the idea of combining the impacts of CS and HS on deposition performance. The charge substitution was further increased and high charge density polymers were prepared at three levels of hydrophobic substitution: low, medium, and high 12 (Fig. 2B). According to the data presented in Figure 2B, a step-change in silicone deposition on hair from PQ-67 shampoos occurred when the charge substitution in polymers exceeded 2 wt.% cationic nitrogen. Experi- mental high charge density PQ-67 polymers deposited up to ~3,500 microgram silicone per gram European virgin brown hair, depending on their CS and HS. They significantly outperformed other PQ-67 and cationic guar benchmarks used in the study. In a second study a series of high charge density PQ-67 13 shampoos were formulated with fractional amounts of polymer (0.07-0.25 wt.%) or silicone (0.3 wt.%). These shampoos were evaluated for silicone deposition in comparison to complete formulations (Shampoo For- mulation A) containing 0.25 wt.% cationic guar and 1 wt.% silicone. According to Figure 3A, the amount of deposited silicone was proportional to the amount of the high charge density PQ-67 polymer added to the formulation. Less then one third of the PQ-67 amount (0.07 wt.% versus 0.25 wt.%) was enough to match the silicone depo- sition from the cationic guar formula. In addition, data presented on Figure 3B shows that the formulation containing one third of the amount of silicone (0.3 wt.% versus 1.0 wt.% silicone in a "complete" Shampoo Formulation A) and high charge density PQ-67 polymers yielded silicone deposition on hair that was similar to the deposition from a "complete" formulation containing cationic guar. 12 All polymers described in this paper had HS 0.01. 13 PQ-67 polymers containing 2. 5 wt.% N.

2006 TRI/PRINCETON CONFERENCE 427 A. Baseline (untreated) Before combing ,B. PQ-67 Cationic guar Figure 4. Volume and frizz control. C. After combing PQ-67 Cationic guar Subjective panel evaluation on tresses. To confirm that the effects described above were perceivable to human subjects, pairs of commercial frizzy hair tresses were shampooed, dried overnight and distributed to five expert panelists skilled in evaluating condition- ing and other properties of hair. Each pair had one tress treated with Shampoo A formulated with a high charge density PQ-67 polymer14 and one tress treated with a control shampoo containing cationic guar. Panelists were asked to evaluate three at- tributes: they were asked to choose one hair swatch in each pair that had less volume/ frizz, was easier to comb and felt smoother/softer. Each panelist performed evaluations twice on different pairs of hair tresses. Photos of the swatches were taken before treat- ment (Figure 4A), after treatment before combing (Figure 4B), and after repeated combing (Figure 4C). As shown in Figure 4, the high charge density PQ-67 formulation provided excellent volume control for frizzy hair. Its superior performance compared to the cationic guar control was clearly noticeable before and after the hair was combed (Figure 4). The results of the subjective panel evaluation are presented in Figure 5A. The study con- firmed that the PQ-67 formulation was perceived by panelists as providing better volume control (10/10) and also significantly improving dry feel (8/10)1 5 and dry comb (9/10)16 of frizzy hair against the cationic guar. As previously discussed, the high charge density PQ-67 polymers were significantly more efficient in depositing silicones on hair compared to the cationic guar control (Figure 3B). Therefore, a second panel evaluation study was conducted to compare a complete formulation with cationic guar to a sample formulation containing a PQ-67 polymer 17 and only about one third of the amount of silicone (0.3 wt.% versus 1.0 wt.%). Hair tresses treated with the formulations were evaluated wet and dry in pairs in the same way as described above. The results of wet/dry comb and feel property evaluations are presented in Figure 5B. It was found that the high charge density experimental PQ-67 polymer used in this study significantly im- 14 PQ-67 polymer with %N -2.5 and medium HS was used in this study. 15 Exact significance level = 89% (binomial distribution). 16 Exact significance level = 98% (binomial distribution). 17 PQ-67 polymer with 2.5 wt.%, medium HS.