I'm trying to understand a Drug Delivery system preparation by polymerization of micro-emulsion. The author shifted gears suddenly from talking about the surfactants to polysaccharides Emulsifier. It seemed to me as if the latter is a subtype of the former.
A surfactant is basically any compoud that affects the surface tension between any two phases.
An emulsifier is indeed a type of a surfactant, acting to either produce or stabilise an emulsion.
Yes, you are very correct. in addition, if the surfactant is to be used in an emulsion formulation, the term emulsifier or emulsifying agent is most applicable.
There are more than one definition for "Emulsifier", for instance:
1.
a substance that stabilizes an emulsion, in particular an additive used to stabilize processed foods.
2.
an apparatus used for making an emulsion by stirring or shaking a substance.
On the other hand, "Surfactants" are compounds that lower the surface tension (or interfacial tension) between two liquids or between a liquid and a solid. Surfactants may act as detergents, wetting agents, emulsifiers, foaming agents, and dispersants.
There is a fine line between surfactant and emulsifier:
Surfactant s must lower the interfecial tention between water and oil phases to a great extent depending on the concentration. On the other hand, emulsifiers not necessarily do that effect and usually perform their action by film forming properties around oil droplets (as in gum Arabic, gum tragacanth, ... etc) or by increasing the viscosity of the aqueous continuous phase (as in xanthan gum, guar gum, .. etc..) so prevent the dispersed oil droplets from flocculation and coalescence .
One more difference: ionic Surfactants my not work with hard water (filled with Ca salts) but emulsifiers work with hard water and soft water too.
Wishing that can help
Amr Edris
Egypt
Dear mohammed
They are the same structure with an differentes characteristics and properties
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