Fragrance solubilization in temperature insensitive aqueous microemulsions based on synergistic mixtures of nonionic and anionic surfactants

Well-defined tetraethylene glycol monooctylether (C8E4) and its commercial polydispersed counterpart (Dehydol® O4) were used to solubilize fragrances. Addition of small amounts (≤1 wt.%) of the ionic surfactants, sodium dodecylsulfate (SDS) or sodium lauryl ether sulfate (SLES), permits the formulation of temperature insensitive fragrance in water microemulsions. The investigation of the pseudo-ternary surfactants/β-pinene/water systems allows the determination of the optimum temperature T* as well as the assessment of the efficiency of the surfactant mixtures to solubilize β-pinene. A mixture of Dehydol O4 and SDS (9/1 wt.%) can solubilize 6.5 wt.% of β-pinene in water within the temperature range of 25–80 °C. This synergistic formulation was also applied to the solubilization of p-cymene, the essential oils pinus pinaster and pinus sylvestris and a true fragrant mixture composed of 9 terpenes and terpenoids in dipropylene glycol.