How do you break a microemulsion?
Microemulsions may be broken by a variety of mechanisms, such as by chemicals or by temperature changes. However, the most simple way of breaking is by dilution. An example of a microemulsion that caries a corrosion inhibitor is listed in Table 6.1. The formulation in Table 6.1 can be easily diluted to the water phase.
What is the difference between emulsion and microemulsion?
Emulsions are stable dispersions of immiscible liquids, but they are not thermodynamically stable. We say that they are kinetically stable. These type of dispersions are sometimes called macroemulsions. Microemulsions, on the other hand, are thermodynamically stable.
How do you explain microemulsions?
Microemulsions are clear, thermodynamically stable isotropic liquid mixtures of oil, water and surfactant, frequently in combination with a cosurfactant. The aqueous phase may contain salt(s) and/or other ingredients, and the “oil” may actually be a complex mixture of different hydrocarbons.
How do you make microemulsions?
Microemulsions (MEs) are clear, thermodynamically stable, optically isotropic systems. They are formed spontaneously upon mixing a suitable oil, water, and an amphiphile blend (surfactants either alone or in combination with a cosurfactant; (1–4)).
Why are microemulsions optically transparent?
3. Most emulsions are opaque (white) because bulk of their droplets is greater than wavelength of light and most oils have higher refractive indices than water. 3. Microemulsions are transparent or translucent as their droplet diameter are less than ¼ of the wavelength of light, they scatter little light.
What is Cosurfactant?
Definition of cosurfactant : a chemical substance that is used in addition to a surfactant to improve its performance especially : a second surfactant that is used in conjunction with a primary surfactant.
Why is microemulsion thermodynamically stable?
Micro-emulsion is thermodynamically stable as its Gibbs free energy caused by some effects becomes negative. Then the micro emulsion become thermodynamically stable.
How many types of microemulsions are there?
three kinds
There are three kinds of microemulsions: oil dispersed in water (o/w), water dispersed in oil (w/o), and bicontinuous. The presence of o/w droplets is likely to be a characteristic of microemulsions where the amount of oil is low.
Why do microemulsions form spontaneously?
Both hydrophilic and hydrophobic drug can be delivered through microemulsion. They are thermodynamic stable thereby rendering (long shelf life). They can be easily formulated since they carry zero interfacial and hence forms spontaneously without the requirement of extra efforts to manage interfacial tension.
Are all surfactants amphiphilic?
Surfactants are normally amphiphilic molecules with a long hydrocarbon tail and a polar head group. The head group may be anionic, cationic or nonionic and accordingly the surfactants are classified as anionic, cationic or nonionic.
What is a microemulsion?
The term “microemulsion” was first used even later by Schulman et al. [3] in 1959 to describe a multiphase system consisting of water, oil, surfactant and alcohol, which forms a transparent solution. There has been much debate about the word “microemulsion” to describe such systems [4].
How to address changes in film curvature and microemulsion type?
Changes in film curvature and microemulsion type can be addressed quantitatively in terms of geometric requirements. This concept was introduced by Israelachivili et al. and is widely used to relate surfactant molecular structure to interfacial topology. As described in Section 2. 3.
Can microemulsion enhance the permeability across the GI barrier of fenofibrate?
Our work is aimed at exploring the composition and the properties of microemulsion (ME), as a drug delivery system, to enhance the permeability across the gastrointestinal (GI) barrier of fenofibrate, a BCS class II drug. It is a prodrug that is converted rapidly after oral administration into a major active metabolite which is the fenofibric acid.
What is the ternary phase diagram of a microemulsion?
At constant temperature and pressure, the ternary phase diagram of a simple three-component microemulsion is divided into two or four regions as shown in Figure 3. 8. In each case, every composition point within the single-phase region above the demixing line corresponds to a microemulsion.