1. Properties
1.1. particles unavoidably form dynamic inhomogeneous structures on small length scale.
1.2. highly unstable systems and require an emulsifying agent or emulsifier ( These are usually surface active agents also known as “surfactants”)
1.3. prepared by continuous mixing or agitation of the two phases When kept for longer periods of time or in case of absence of an emulsifying agent, the phases in the emulsion tend to separate, resulting in “cracking of emulsion” or ” phase inversion”.
2. Mechanisms of Emulsification
2.1. Surface tension theory
2.1.1. According to this theory, emulsification takes place by the reduction of interfacial tension between two phases
2.2. Repulsion theory
2.2.1. he theory proposes that the emulsifying agent creates a film over one phase that forms globules, which repel each other. This repulsive force causes them to remain suspended in the dispersion medium
2.3. Viscosity modification
2.3.1. Certain emulgents such as acacia, tragacanth, carboxymethylcellulose, polyethylene glycol, etc increase the viscosity of the medium, which helps create and maintain the suspension of globules of the dispersed phase
3. Instabilities
3.1. Flocculation
3.1.1. When the particles or droplets of the dispersed phase aggregate together on account of attractive forces, the phenomenon is known as flocculation and results in an unstable system. Flocculation is mainly observed in case of oil in water type of emulsions.
3.2. Coalescence
3.2.1. When the droplets of discontinuous phase bump into each other to form a larger droplet thus increasing the average particle size over time, it is known as coalescence which is a form of instability.
3.3. Creaming
3.3.1. When the droplets in an emulsion rise to the top of the emulsion under the influence of buoyancy or centripetal force, it results in the creaming of emulsion
3.4. Ostwald Ripening
3.4.1. It describes the change of an inhomogeneous structure over time, i.e., small crystals or sol particles dissolve and redeposit onto larger crystals or sol particles. Ostwald ripening is generally found in water-in-oil emulsions
4. is Mixture of 2 Liquids or More That are Normally immiscible
4.1. unmixamble
4.2. unblendable
5. Types
5.1. Oil in water
5.1.1. Oil is Dispersed Phase
5.2. Water in Oil
5.2.1. Aqueous phase is Dispersed Phase
6. Uses
6.1. As Food
6.1.1. Oil-in-water emulsions are common in food products. Examples include butter, margarine, homogenized milk, mayonnaise, etc
6.2. Healthcare
6.2.1. Many cosmetic and pharmaceutical dosage forms are in the form of emulsions. Cosmetics such as lotions, creams, biphasic makeup removers are in fact emulsions. Many oral, as well as topical dosage forms, are emulsions. Microemulsions are used to deliver vaccines and kill microbes. Cod liver oil, cortisol, polysporin are some examples of emulsion formulations.
6.3. Chemical Synthesis
6.3.1. Emulsions are used in the manufacturing of polymer dispersions. These include primary components of glues and paints.