Factors influencing the deposition of conditioning polymers

There was an interesting article in the November/December 2013 issue of the Journal of the Society of Cosmetic Chemists.  The research titled "Use of Statistical Modeling to Predict the Effect of Formulation Composition on Conditioning Shampoo Performance" explains how researchers were able to use a mathematical model to optimize shampoo formulations for the deposition of conditioning polymers. 

Method summary

Basically, the researchers created a basic shampoo formulation with water and varying levels of three surfactants, Sodium Lauryl Ether Sulfate (SLES), Sodium lauryl Sulfate (SLS), and Cocamidopropyl betaine.  They also included cationic polymers including cassia derivatives, guar, and hydroxyethyl cellulose.  Using various prototypes, they were able to demonstrate the effect of different parameters on the deposition of the polymer on hair.  They measured polymer deposition using a Direct Red 80 dye colorimetric test.  That's a pretty standard test of cationic deposition.

Research summary

It turned out there were three primary factors that influenced the amount of conditioning.  This included

1. Surfactant amount - less surfactant resulted in more deposition
2. Micelle charge - Increase micelle charge lead to more deposition
3. Ionic strength - Higher the ionic strength of the polymer, the more deposition

Interesting work.  So, if you are formulating a  cleansing product and want to have more deposition of your conditioning ingredients, use less surfactant and a higher charged polymer.