Cremophor(R)a25

• CAS: 68439-49-6
• Catalog Number: ACM68439496-1
• Category: Main Products
• Molecular Weight: 0
• Molecular Formula: C₁₈H₃₈O
• Synonyms: alcohols,c16-18,ethoxylated;Alcohols,C16-18-ethoxylated;AliphaticC16-18-alcohol,ethoxylated;C16-18-Alkylalcohol,ethoxylate;C16-18-Alkylalcoholethoxylate;cremophor¨a25;ethoxylatedfattyalcohols(c16-18);CETEARETH-2
• Hazard Statements: N
• Safety Description: 60-61
• Supplemental Hazard Statements: H302-H315-H319-H400
• Symbol: GHS07,GHS09

Case Study

Preparation of Nanoemulsions with Cremophor A25

Fernandez, Patrick, et al. Colloids and Surfaces A: Physicochemical and Engineering Aspects 251.1-3 (2004): 53-58.

The droplet size distribution of an emulsion determines the properties of the emulsion, such as long-term stability, texture and optical appearance. Therefore, methods to control the droplet size during the emulsification process are of interest when well-defined emulsion properties are required. In this work, emulsions consisting of water, paraffin oil and mixtures of nonionic surfactants such as Cremophor A25 and fatty alcohols were studied by laser scattering. The effect of the preparation route as well as the surfactant concentration on the droplet size distribution was investigated. Above the critical surfactant to oil ratio and following the standard approach of emulsion phase inversion, a large number of oil droplets with a diameter of less than 1 μm are obtained. When the emulsification approach is changed and thus phase inversion is avoided, such fine droplets are absent and the droplet size distribution is controlled solely by the input of mechanical energy. Phase inversion emulsification exploits two effects to achieve finely dispersed oil-in-water emulsions. The lamellar or bicontinuous structure formed by the surfactant at the inversion point determines the size of the resulting droplets, while the corresponding minimum interfacial tension favors droplet formation, which explains why the droplet size distribution depends only on the weight ratio between surfactant and oil and not on the water concentration.
Emulsions were prepared with CremophorA6 and CremophorA25, distilled water and paraffin oil. CremophorA6 is a nonionic surfactant composed of polyethylene glycol alkyl ether (ceteareth-6; CE, i = 16-18, j = 6) and stearyl alcohol in a weight ratio of 3:1. CremophorA25 is also known as ceteareth-25 (CE, i = 16-18, j = 25). The weight ratio of CremophorA6/A25 was fixed at 7:3. The total mass of each sample (whose composition is shown in Table 1) prepared was 300 g, and the weight ratio of water to oil was kept constant at 3.5. The surfactant was mixed into the oil phase at 80°C before emulsification. The aqueous phase (also at 80 °C) and the oil phase were mixed with a stirrer at 150 rpm and subsequently homogenized at 13,000 rpm for 1 min. The samples were cooled to room temperature under moderate stirring at 150 rpm.

Cremophor A25 in rheology modifier studies

Fernandez, Patrick, et al. Colloids and Surfaces A: Physicochemical and Engineering Aspects 262.1-3 (2005): 204-210.

Vesicles are self-assembled spherical aggregates of amphiphilic molecules with rich structural diversity. They have attracted increasing attention due to their possible applications in the pharmaceutical and cosmetic fields, but also from a more fundamental point of view. Here, the formation of vesicles in commercial surfactant mixtures is demonstrated. It is shown how the admixture of nonionic surfactants such as Cremophor A25 leads to vesicle formation by adjusting the packing parameters of the mixture. The high-frequency viscosity data can be described by an effective hard-sphere system applying the Lionberger-Russel model. Therefore, the hydrodynamic volume of the vesicles as well as their average size can be estimated, which agrees well with the structures observed by transmission electron microscopy.
Cremophor A6 and Cremophor A25 are nonionic surfactants. Cremophor A6 is a mixture containing 75% of polyethylene oxide alkyl ether (CE with i = 16-18 and = 6) and 25% of stearyl alcohol. Cremophor A25 is a polyethylene oxide alkyl ether with a relatively long ethylene oxide chain length (CE, i = 16-18 and = 25). The densities of Cremophor A6 and Cremophor A25 are approximately 0.9 and 1.02 g/ml (60°C), respectively. Water and surfactant were mixed in various compositions at 80°C under stirring. This was followed by homogenization at 13 000 rpm for 1 min. The samples were cooled to room temperature under moderate stirring at 150 rpm and then stored at room temperature. For emulsion measurements, 20 vol.% paraffin oil with a viscosity of 230 mPa·s was emulsified in a mixture of Cremophor A6/Cremophor A25 (7:3) and sodium dodecyl sulfate and subjected to transmission electron microscopy (TEM) measurements as well as optical microscopy experiments. To study surfactant vesicles in TEM, a small drop of the sample is flash frozen in liquid ethane at -183 °C and freeze-fractured in an evaporation chamber. Freeze etching by ice sublimation at high temperature (-120 °C) leads to the morphology of the vesicular phase at the fracture surface. This morphology is replicated by oblique evaporation of a thin Pt/C layer, which now contains morphological information of the vesicles. The replica is cleaned of adhering surfactant material in a chromium-sulfuric acid mixture at room temperature and imaged in a transmission electron microscope (freeze-fracture TEM).