Investigation of Surfactant Structure in Shampoo

A number of personal care products comprise of concentrated surfactant systems featuring a multi-phasic microstructure. A familiarity with this structure can facilitate the development of new product features, and also control the properties of the formulation during production.

The study of how the structure changes during usage (as in the case of diluting with water) or the stability of the formulation throughout storage is also essential in order to guarantee that the quality of the end product is good.

X-ray scattering is an indispensable technique for determining the organization of the associated micellar formulation on a wide range of length scales, as a function of the environment. This technique also greatly complements the Cryo-TEM and NMR.

Figure 1. 1D SAXS/WAXS curve from Head & Shoulders Classic Clean Shampoo sample. Exposure time = 600 s.

Measurements and Results

The sample that was investigated is Procter & Gamble's Head and Shoulders "Classic Clean" shampoo. Simultaneous SAXS/WAXS measurements were performed under vacuum at room temperature.

Thanks to the single shot measurement, the same sample portion is illuminated during both WAXS and SAXS data collection, and precise data collection is obtained, and acquisition time is shortened.

Figure 1 depicts the resulting 1D curve.

The SAXS/WAXS pattern obtained presents a structure made of:

• A wormlike micelle, presented by a form factor with two observed orders corresponding to the cross-section signature, and a slope change at smaller q- values related to the characteristic dimension of 38.31 nm.
• A crystalline phase defined by clearly characterized peak positions from WAXS measurements, and a sponge phase

Conclusion

SAXS/WAXS measurements were carried out on the Head and Shoulders Shampoo from Procter & Gamble and its inner structure was studied.

Further sample investigation can be done with the Nano-inXider under temperature control, by deploying the integrated temperature control stage, the Linkam HFSX350.

The SAXS/WAXS single shot measurement enables a proper temperature investigation as the hysteresis phenomenon can be avoided without sample replacement.

This information has been sourced, reviewed and adapted from materials provided by Xenocs.

For more information on this source, please visit Xenocs.