2010 TRI/PRINCETON CONFERENCE 173 It is important to note that the micelles are made up of mixtures of all of the surfactants that are in the shampoo. In fact, it is commonly assumed that the relative amount of each surfactant in a micelle is the same as in the bulk formulation. This means that the average surfactant charge is a convenient measure of the potential that would exist on each mi- celle. Thus, it will be considered to be a theoretical measure of micelle charge density. The relative sizes of the micelles can be estimated from the viscocity of the shampoos it- self. Since the micelles primarily increase in one dimension, a convenient description of micelle size is aspect ratio. This terminology will be used here. An estimate of this value has been obtained in previous work (14) by modeling the change of the Brookfi eld viscos- ity measured at 20rpm with the various surfactant blend composition (in terms of SLES-3, CAPB and SLS content) and Equation 4 summarizes the modeling fi t. Aspect ratio = wt% CAPB + 0.8* wt% SLS + 0.15* wt% SLES 3 + 0.15*(wt% SLS 2.1) *(wt% CAPB 4.1) - - - (4) This measure of aspect ratio is not a pure one. It is partially confounded with the amount of surfactant that is in the formulation as well as the amount of salt. Thus, it should be only considered as a rough estimate of size. These factors will be used to rationalize per- formance. For the silicon deposition data presented above, the micelle aspect ratio and total micelle charge were calculated for each surfactant blend. The ratio of aspect ratio to micelle charge against the total silicone deposition for each cationic cassia polymer is plotted in Figures 13 and 14. It can be seen from the P value in Figure 13 that in the case of the higher cationic charge cassia polymer, there is a relatively high confi dence level (98%) that these factors are important in explaining silicone deposition. The results show that as the ratio of the aspect ratio to micelle charge increases, the silicone deposition with EX-906 decreases, i.e. the conditioning performance decreases. The ratio shown is an indirect measure of the inverse of micelle charge density (as the micelle charge density increases, the silicone deposition increases). Thus, the data show that micelles having a Figure 13. Correlation of silicone deposition with the ratio of aspect ratio to micelle charge for EX-906 (3.0 mEq/g).

Purchased for the exclusive use of nofirst nolast (unknown) From: SCC Media Library & Resource Center (library.scconline.org)