Theories of emulsification (Emulsion: A liquid dosage form)

Theories of emulsification (Emulsion: A liquid dosage form)

Theories of emulsification (Emulsion: A liquid dosage form)

By Bryan Wright 6 Comments October 11, 2019


Theories of emulsification Three basic mechanisms are involved in emulsion formation 1. Reduction in interfacial tension 2. Formation of rigid interfacial film, i.e. formation of mechanical barrier 3. Formation of electrical double layer on the surface of oil/water droplet Reduction in interfacial tension Emulsion is the dispersion of two immiscible liquids When you mix oil with water, and stir; the oil/water droplets will be dispersed in continuous phase At that time, the surface area increases so, the surface free energy also increases by the equation when water and oil are mixed together, at that time one phase is dispersed as fine droplet in the continuous phase At, that time the formation of droplet increases the surface area Increase in surface area increases surface free energy and the system becomes unstable In order to stabilize this particular system, we have to reduce the interfacial tension, surfactants are most commonly used to reduce the interfacial tension surfactant contain polarpart and non-polar part Besides this, surface active agents form monomolecular film on the surface of the dispersed droplet By this way they prevent coalescence and subsequent breaking of the emulsion So, the surface active agents perform two functions: 1. Reduction of interfacial tension 2. Formation of monomolecular film that prevent coalescence of dispersed droplets. Formation of rigid interfacial film This can be achieved by use of the hydrophilic polymers. Hydrophilic polymers such as acacia, veegum, carboxymethyl cellulose, HPMC, methyl cellulose, They form multimolecular film on the surface of the dispersed droplets I have discussed mechanism of hyrophilic polymers as an emulsifying agents in separate video Third mechanism is: Formation of electrical double layer Oil droplet contains specific charge, whether it is negative or positive suppose oil droplet contains negative charge on the surface so that it will adsorb positive ions from the solution This is a tightly bound layer This first layer is tightly bound Besides this tightly bound layer, there is a loosely bound layer of the opposite charge This is a loosely bound layer of the opposite charge The surface of the loosely bound layer is called as a shear plane or sleeping plane The charge on the shear plane is called as the zeta potential Due to this zeta potential, the oil droplets repulse each other in the dispersion There is a some electrical barrier between oil droplets so that oil droplets repulse each other and remain in dispersed form in the dispersion and does not fuge together, and this prevents coalescence and breaking of the emulsion

6 Comments found

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Nadine17

That was very helpful, thanks

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DIPANKAR DUTTA

very useful for physical pharmacy….subject

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darshika verma

helpful and concepts are clear by viewing. thanks 🙂

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Shraddha Srivastava

very helpful video. Sir, can you suggest reference book on this……

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Syed Rizwan

HELPFUL

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Manasa Kollu

We want more explanation on stability, preservation and theories of emulsion videos we want more

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