Semi-Solid o/w Emulsions Based on Sucrose Stearates: Influence of Oil and Surfactant Type on Morphology and Rheological Properties

Abstract

Sucrose stearate blends of intermediate lipophilicity are mild surfactants with thermosensitive gelling behavior. Binary systems and emulsions with sucrose stearate S-970 or S-1170 were developed and investigated by thermoanalytical and rheological measurements. The presence of an oil phase promoted the gelling potential of the esters especially at higher production temperatures. Semi-solid emulsions with viscoelastic properties comparable to weak gels were obtained with different dermatologically acceptable oils. The complex internal structure as visualized by fluorescence microscopy exhibited changes during storage in dependence of oil and surfactant type. A combination of S-970 with cetearyl ethylhexanoate-based oil phases led to superior physical stability.

Keywords:

• Fluorescence microscopy
• semi-solid
• sucrose stearate

Acknowledgments

The authors would like to thank Elham Rezvani and Gerhard Schleining of the University of Natural Resources and Life Sciences, Vienna, and Xueyan Wang of the University of Vienna for technical assistance. The financial support of the research platform “Characterisation of Drug Delivery Systems on Skin and Investigation of Involved Mechanisms” is gratefully acknowledged.

Notes

*The aqueous sucrose ester dispersions of either S-970 or S-1170 were prepared at 25°C, 40°C, or 60°C and their dynamic viscosity was compared at a shear rate of 50 s⁻¹. Values are given as means ± SD of at least three experiments (n ≥ 3).