424 JOURNAL OF COSMETIC SCIENCE dimethicone with an average particle size -0.3 microns,7 and conditioning polymers incorporated at 0.25% level and Shampoo Formulation B containing sodium laureth sulfate (SLES)/ disodium laureth sulfosuccinate (DSLSS)/ cocamidopropyl betaine (CAPB), 1 wt. % dimethiconol with average particle size -0.5 micron8 and conditioning polymers incorporated at 0.2% level. Deposition of silicones from shampoo formulations depends upon many factors type of silicone, its average particle size, the surfactant base, the presence and type of cationic polymers are amongst the most important (6,11). Hair type can also play a significant role in the deposition of silicones and, therefore, impact the choice of cationic polymers to assist in and/or control this deposition. For example, as we previously described in (1) and the SoftCAT product literature, the low to medium charge density (-1.0 to 1.45 wt.% N) PQ-67 polymers ideally suit the needs of bleached damaged hair. They do not overload this susceptible-to-cationic-deposition hair type while maximizing the deposition of much needed silicone as compared to cationic guar and PQ-10 polymers. Deposition of silicone on virgin hair as well as on any "interme- diate" hair type varies significantly depending on a specific shampoo formulation. Ex- amples of systems where high-viscosity high-charge PQ-10 grades outperformed their cationic guar counterparts have been previously described in (11). As we show later, Shampoo Formulation B also falls into this category. At the same time, the Shampoo Formulation A yielded significantly better silicone deposition on European virgin brown hair when formulated with cationic guar.9 One of the goals of the present study was to further explore and tune structural parameters of PQ-67 polymers in order to close this gap. We, therefore, began our investigation with the Formulation A, where the short- coming was first identified, and then expended our evaluation scope to include other systems. Conditioning performance of two prototype shampoo systems described below is largely due to the presence of silicones and their ability to reach hair and stay behind (in small amounts) after the rinse-off cycle is complete. Ability to deposit silicone is therefore crucial in these systems and greatly contributes to the overall conditioning effect. On the other hand, the contribution of the cationic conditioning polymers and other ingredients found in shampoos can also play an important role in the overall performance. In order to account for these effects and make sure that the performance differences are likely to be noticed and appreciated by the end consumer, we included subjective panel studies on hair tresses in our evaluation. Performance in Shampoo Formulation A Silicone deposition. The total amount of silicone deposited on hair treated with the Shampoo Formulation A was measured using atomic absorption spectrophotometry. Commercial European virgin hair10 was washed two times 11 with each formulation. The 7 Dow Corning® Emulsion 1664 (supplied by Dow Corning) is a non-ionic emulsion of high molecular weight polydimethylsiloxane with 50% silicone content. 8 Dow Corning® Emulsion 1785 (supplied by Dow Corning) is an anionic emulsion of high molecular weight polydimethylsiloxane with 60% silicone content. 9 Note that the exact same shampoo formulation with lower charge density PQ-67 polymers (SoftCAT SL grade) yielded superior deposition of silicones on single-bleached hair compared to cationic guar (1). 10 All hair used in this work and described in this paper was supplied by International Hair Importers Co. 11 Consecutive washings, no drying in-between.

2006 TRI/PRINCETON CONFERENCE 425 silicone was extracted from the hair by a 50/50 (v/v) methyl isobutyl ketone/toluene solution. The silicone content was measured, and then the micrograms of silicone per gram of hair was calculated. Deposition of silicone on European virgin brown hair from the prototype Shampoo A formulated with PQ-10 polymers, PQ-67 polymers, and cationic guar is shown on Figure 2A. According to this data, increasing the charge substitution in PQ-10 polymers (HS = 0) resulted in more silicone deposited on hair. A moderate increase from -45 to 95 micrograms of silicone per gram of hair was observed. This trend became more pronounced in the PQ-67 group compared to PQ-10. The same increase of cationic charge from -1.0 to 1.8 wt.% N resulted in a several fold boost of silicone deposition from PQ-67 formulas: from -45 to 215 micrograms of silicone. 700 ... ca 600 .c CJ 500 ::::: 400 (/J E 300 l! CJ 200 CJ 100 E 0 3600 ... ca 3000 .c CD 2400 - U'J 1800 E ca 1200 CD u 600 E 0 HS= 0 (PQ-10) I □o/oN-1.0 Low HS (PQ-67) Cat. guar ■ %N -1.25 mo %N -1.a I Low HS Medium HS High HS Cat. guar ■ %N-1.25 ■ %N-1.45 DD1 %N-1.8 II %N-2.1 ■ %N-2.5 Figure 2. Silicone deposition from Shampoo Formulation A on European virgin brown hair. A. Polymers PQ-10 and PQ-67 with CS of 1.0-1.8 wt.% N. B. PQ-67 with CS 1.25-2.5 wt.% N and cationic guar.