Surface active agents

SURFACTANTSSURFACTANTS

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PRESENTS BYPRESENTS BYPRADEEPKUMAR YADAVPRADEEPKUMAR YADAV

RAMNIRANJAN JHUNJHUNWALA RAMNIRANJAN JHUNJHUNWALA COLLEGECOLLEGE

MSC(II) (PHYSICAL CHEMISTRY)MSC(II) (PHYSICAL CHEMISTRY)SEM – (III) ( 2013 – 14 )SEM – (III) ( 2013 – 14 )

CONTENTSCONTENTS

• INTRODUCTIONINTRODUCTION

• C.M.CC.M.C

• MICELLAR SOLUBILIZATIONMICELLAR SOLUBILIZATION

• TYPES OF SURFACTANTSTYPES OF SURFACTANTS

• PROPERTIESPROPERTIES

• APPLICATIONSAPPLICATIONS

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SURFACTANTSSURFACTANTS

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Molecules and ions that are absorbed at the interface is termed as Surfactants

Surfactants have two distinct regions in their chemical structure, one of which is water-liking or Hydrophilic and the other of which is water-hating or Hydrophobic.

These molecules are referred to as Amphiphilic or Amphipathic molecules or simply as Surfactants or Surface active agents.

The functional groups such as alcoholic (-OH), carboxylic acid (-COOH), sulphate (-SO4) & quaternary ammonium(NH4

+) contribute to hydrophilic portion

Alkyl chains contribute to lipophilic nature of molecules

The polar end oriented towards the water as well as the non polar end projected upwards to space.

SURFACTANTSSURFACTANTS

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• When a surfactant is placed in water it forms micelles at concentrations above its critical micelle concentration(CMC), they form aggregates known as micelles.

• In a micelle, the hydrophobic tails flock to the interior in order to minimize their contact with water, and the hydrophilic heads remain on the outer surface in order to maximize their contact with water .

CMCCMC

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• Critical micellar concentration is the concentration at which the monomeric surfactant molecules associates into small aggregates called micelles. • Diluting the surfactant solution to below the cmc causes themicelles to disperse or break up into single or non associatedsurfactant molecules.• Micelles are not static aggregates but dissociate, regroup andreassociate rapidly.• There is a dynamic equilibrium between single surfactant molecules and micelles.• The shape of micelles in dilute surfactant solutionsis approximately spherical.

CMCCMC

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•Solubilization can be defined as the spontaneous dissolving of a substance by reversible interaction with the micelles of a surfactant in water to form a thermodynamically stable isotropic solution with reduced thermodynamic activity of the solubilized material.•At surfactant concentrations above the cmc the solubility increases linearly with the concentration of surfactant, indicating that solubilization is related to micellization.•The lower is the CMC value and higher the aggregation number , the more stable are the micelles.

Micellar solubilizationMicellar solubilization

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Surfactants, Types Surfactants, Types

•Anionic: Sodium dodecyl ( lauryl)sulfate ( SLS)

•Cationic: Dodecyltrimethyl ammonium bromide(DTAB)

•Nonionic: Tweens, Spans

•Zwitterionic(Amphoteric): Lecithin(Phospholipids), Others

• Nontraditional: Bile salts

•Drugs: Dexverapamil-HCl, ibuprofen, and benzocaine.

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Anionic surfactantsAnionic surfactants

• Sodium Lauryl Sulphate BP

• Mixture of sodium alkyl sulphates, the chief of which is sodium dodecyl sulfate, C12 H25 SO4 – Na+

• It is very soluble in water at room temperature, and is used

• pharmaceutically as a preoperative skin cleaner, having

• Bacteriostatic action against gram-positive bacteria, and also in medicated shampoos

• Component of emulsifying wax.

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Cationic surfactantsCationic surfactants

• cationic surfactants are important pharmaceutically because of their bactericidal activity against a wide range of gram-positive and some gram-negative organisms.

• They may be used on the skin, especially in the cleaning of wounds.

• Their aqueous solutions are used for cleaning contaminated utensils.

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Non-ionic surfactantsNon-ionic surfactants

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• These are not ionised in aqueous solution

• Polyoxy ethylene sorbitan fatty acid esters

• Sorbitan esters are supplied commercially as Spans and are mixtures of the partial esters of sorbitol and its mono- and di-anhydrides with oleic acid.

• They are generally insoluble in water (low hydrophile –lipophile balance (HLB) value) are used as water-in-oil emulsifiers and as wetting agents.

Non-ionic surfactantsNon-ionic surfactants

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• Polysorbates are complex mixtures of partial esters of sorbitol and its mono and di-anhydrides condensed with an approximate number of moles of ethyleneoxide.

• They are supplied commercially as Tweens. The polysorbates are miscible with water, as reflected in their higher HLB values, and are used as emulsifying agents for oil-in-water emulsions.

PROPERTIESPROPERTIES

- Wetting- Wetting- Emulsification- Emulsification- Dispersion / Solubilization - Dispersion / Solubilization - Foaming / De-foaming - Foaming / De-foaming - Detergency- Detergency- Conditioning- Conditioning- Thickening- Thickening

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WETTINGWETTING

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•Paraffin or new cotton cloth barely wetted by water, but when surfactant is added to water their surface easily becomes wet

•Surfactant in floor cleaner as a wetting agent

EMULSIFICATIONEMULSIFICATION

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Examples of Emulsions

EMULSIFICATION EMULSIFICATION

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Foam consist of gas covered with thin liquid film.

Surfactant molecule absorbed to interface between

gas and liquid

FOAMING EFFECTFOAMING EFFECT

DETERGENCYDETERGENCY

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APPLICATIONSAPPLICATIONS

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PHARMACEUTICAL ADJUVANTSThey are added to the drugs in order to increase the product

characteristics in the design of dosage forms in a variety of ways like solublising agents, wetting agents ,detergents, suspending ,foaming, emulsifying agents

INFLUENCES THE DRUG ACTIONThese are at low conc. Enhances the penetration of

hexylresorcinol into pinworm ,ascaris.

ANTIBACTERIAL ACTIVITY• These are alter the integrity and lost the essential elements by leak• Mainly cationic surfactants show activity• But non ionic surfacants help in metabolism of organisms & facilitate their

growth• Natural surfactants enhances the absorption of antibiotics

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FOAMING AGENTS:They can be used in shampoos & lathering shaving cream so it

can produce stable foam when mixed with air pockets enclosed with thin film of liquid.

ANTI FOAMING AGENTSThey can be used in fermentation process to prevents the foams in

production .eg., octnol, ether, castor oil & silicones

SOME ARE DRUGS• Phenothiazine & procaine-tranquilizer, local anesthetic• Acridines-antibacterial• Streptomycin-antibiotic• Veratrum alkaloids-anti cancer

APPLICATIONSAPPLICATIONS

REFERENCE

M. J. Rosen. Surfactants and Interfacial Phenomena (3rd

edn.), John Wiley(2004)

R. Zana (ed.). Dynamics of Surfactant Self-Assemblies, CRC

Press (2005)

3. M. Abe & J. F. Scamehorn. Mixed Surfactant Systems, CRC

Press (2004).21

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