Investigation of Surfactant Structure in Shampoo with Small Angle X-Ray Scattering

Many personal care products consist of concentrated surfactant systems with a multi-phasic microstructure. A good knowledge of this structure is required in order to drive the development of new product features, and to control the properties of the formulation during production.

It is also important to study how the structure changes while using the product (as dilution in water) or the stability during storage in order to ensure that the performance of the final product is good.

X-ray scattering is a powerful technique to elucidate the organization of the associated micellar formulation on a broad range of length scales, as a function of the environment. It works extremely well as a complementary technique to Cryo-TEM and NMR.

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

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

Measurements and Results

The sample under study is Procter & Gamble's Head and Shoulders "Classic Clean" shampoo. Simultaneous SAXS/WAXS measurements were carried out under vacuum at room temperature.

Due to the single shot measurement, the same sample portion is illuminated during both SAXS and WAXS data collection, offering precise data collection, and shortening acquisition time.

Figure 1 shows the resulting 1D curve.

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

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

Conclusion

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

Further sample investigation is possible 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 sample replacement is not required for prevention from hysteresis phenomenon.

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

For more information on this source, please visit Xenocs.

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