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Data, Data, Everywhere

By: Steve Herman
Posted: April 6, 2010, from the April 2010 issue of GCI Magazine.

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Robert Lochhead1, 2, 3 is a pioneer in applying combinatorial chemistry to personal care applications. He has used the interaction of a cationic polymer with an anionic surfactant as an example in his publications. And this combination is critical for the modern conditioning shampoo.

The basic science was unraveled by E. Desmond Goddard4 in seminal papers published in the early 1990s. It is complicated unless one is a polymer chemist, but the basic idea is that the interaction of a polymer with a surfactant changes with conditions, such as the amount of solvent present. It is possible for the polymer and surfactant to live happily together for a while but separate upon dilution.

The separation of phases allows the polymer to deposit on the hair, rather than wash off with the surfactant. Since the interactions are complex, a robot generating hundreds of experiments, tools to analyze the results and a computer to turn it into a pretty picture showing the results is a formulator’s dream.

The triangular phase diagram shows regions where coacervates are absent and others with a maximum concentration of phase-separated coacervate. The diagrams are different for every polymer. Surfactant composition and electrolyte concentration are some other key variables.

It is formidable technology, yet it is, in essence, but an extension of a salt curve. Data is gathered, plotted and informed decisions made. It takes the rather haphazard way much cosmetic formulation is done and places it in a formal platform, allowing vastly increased data entry and information processing.