Change of amphiphilic association structures during evaporation from emulsions in surfactant–fragrance–water systems

Abstract

The phase diagrams of a nonionic surfactant (Laureth 4), water, and three different fragrance compounds, limonene, phenethyl alcohol and benzaldehyde, were compared. The location of the fragrance molecules in the lamellar liquid crystals (LLC) was investigated using the small-angle X-ray diffraction. The evaporation processes of the fragrance emulsions, consisting of 80 wt.% water, 15 wt.% fragrance and 5 wt.% surfactant, were followed both experimentally through an optical microscope, and theoretically through calculation based on the knowledge of the vapour pressure of the fragrance along the demixing line of the water-in-oil microemulsion (L(2)) phase boundary. Evaporation of the phenethyl alcohol emulsion led the system directly into the L(2) phase region, with very little phenethyl alcohol evaporated in 20 min. For the limonene system, during evaporation the system experienced several multi-phase regions, then reached the water-surfactant axis, and finally went into the L(2) phase region. By contrast to phenethyl alcohol, limonene evaporated completely within 10 min. Benzaldehyde emulsion went through structural changes similar to those of limonene, while the fragrance evaporated continuously until completion in 20 min.

Development of an Environmentally Friendly Larvicidal Formulation Based on Essential Oil Compound Blend to Control Aedes aegypti Larvae: Correlations between Physicochemical Properties and Insecticidal Activity

“…The decrease of the contact angle and volume of the droplets and the increase of their radius with time may be explained assuming the coupling between the spreading of the droplets on the surface and the evaporation of the water (main component of the studied emulsions). − The results show similar time dependences for the geometrical parameters, independently of the considered emulsions, only variations of the time scales involved in the spreading/evaporation process and the values of contact angle, volume, and radius on the composition of the emulsions are observed from the experimental rate. This may be explained considering that the spreading rate is mainly governed by the oil phase and the copolymer, with the water evaporation, for such diluted emulsions, proceeding with a similar rate than in pure water droplets .…”

Adsorption of Model Perfumes at the Air–Solution Interface by Coadsorption with an Anionic Surfactant

“…The particular focus of this study is perfumes, which are important ingredients in a wide range of surfactant based home and personal care products. − Surface delivery and retention, evaporation into the vapor phase, and the impact upon surfactant self-assembly are the key elements of perfume performance. Although there have been numerous studies on their solubilization into micellar phases and their impact upon surfactant self-assembly − and on evaporation into the vapor phase, − there is relatively little on their adsorption at interfaces . Although fragrances are complex blends of different components, these studies have focused on individual model components with differing degrees of hydophobicity/hydrophilicity, and this approach provides important insights.…”

Probing the surface of aqueous surfactant-perfume mixed solutions during perfume evaporation

“…Most surfactant based home and personal care products contain perfumes as a key element of their performance (1)(2)(3), and this has stimulated extensive research into the different properties of a range of model perfume molecules. The solubilisation of different perfume molecules in a range of surfactant and mixed surfactant solutions has been studied (4)(5)(6)(7)(8), their location within aggregates identified (9)(10)(11), and their impact upon surfactant phase behaviour determined (12)(13)(14)(15). Optimised delivery is an important element and this has stimulated the development of novel encapsulation and delivery systems (16)(17)(18)(19).…”