Effect of added fragrances on the foaming properties of aqueous surfactant solutions

Foaming properties are important characteristics of surfactant solutions used for personal washing products, hair styling foam, shaving foam, etc. Fragrances are often used in these cosmetic products, but they also influence the foaming properties of aqueous surfactant solutions. In this study, we investigated the effects of added fragrances [d-limonene (LN), α-hexyl-cinnamic-aldehyde (HCA), β-ionone (IN), benzyl acetate (BA), linalool (LL), geraniol (GL), eugenol (EL), and cis-3-hexenol (HL)] on the initial foam heights and foam stability of sodium dodecyl sulphate (SDS) aqueous solutions. GL and EL increase the initial foam heights of 0.1 wt% and 0.3 wt% SDS aqueous solutions. Dynamic surface tension measurement shows that these fragrances quickly lower the surface tension of SDS solutions. Hence, GL and EL increase the initial foam heights because of the fast adsorption at the air/water interface. Further, GL and EL also increase the foam stability of SDS solutions and act as foam boosters. For the application to shampoo, the addition of GL results in the largest improvement of the initial foam height and the foam stability among the fragrances investigated here.