Introduction to

Surfactants

Why does surfactant work ?

Water : Hydrophobic Hydrophilic Oil : Lipophilic Lipophobic

What does surfactant do ?

Water & Oil are mortal enemies

Surfactants acts as clamp

binding Water & Oil

are together

Surface Tension –

Force between

two liquids

How does surfactant work?

SurfactantDefinition

Surface Active Agent Substance which reduces surface/interfacial tension

between two phases Compounds having tendency to gather around the interface between two different materials by altering the properties of interface remarkably Serves as good mediator to settle dispute between two phases which are not friends

What is Surface Tension?

The Influence of Surfactants on Surface Tension

Important Property MicelleSmall

Micelle

Extremely Dil. Soln

Dil. Soln Soln at CMC

Soln above CMC

Critical Micelle Concentration

(CMC)

Minimum concentration at which surfactants molecules begin to form micelles

Surfactant Behavior

Structures of Micelles

CMC and Micelles Importance

• Micelles make insoluble material soluble in water.

• The structure of the micelles can affect the viscosity of the solution.

• Micelles are reservoirs of surfactants.

• If not above CMC, the cleaning solution gets depleted of surfactants and cleaning power is lost!!

Important Properties of Surfactants

• Wetting and penetrating effects

• Emulsifying

• Dispersing / Solubilizing effects

• Foaming / De-foaming effects

• Detergency

• Conditioning

• Substantivity

• Thickening

Wetting effectParaffin or new cotton cloth barely wetted by water

ButWhen surfactant is added to water their surfaceeasily becomes wet

Surfactant in floor cleaner as a wetting agent

Wetting

Emulsions

Emulsification

Examples of Emulsions

Foaming effect

Foam consist of gas covered with thin liquid film.Surfactant molecule absorbed to interface betweengas and liquid

Cleaning/DetergencyHow does cleaning take place ?

Real Soil Composition

Required Effects when Cleaning

How Surfactants Work

Types of Surfactants

Ionic Surfactants Anionic Surfactants

Carboxylates

Alkyl benzene Sulphonates

Soaps

LABS

FAS

Ionic Surfactants Anionic Surfactants

Sulfosuccinate

Diester

Sulfosuccinate

Monoester

Ionic Surfactants: Uses Anionic Surfactants

• Cleansing Formulation– Shampoo– Hand wash– Bath gels– Tooth Paste– Soaps & Detergents

Cationic Surfactants(1)

Cationic Surfactants(2)

Important Property Substantivity

Cationic Surfactants

Ionic Surfactants Amphoteric Surfactants

N+

CH3

CH3

CH2COO-

CONH(CH2)3N+

CH3

CH3

CH2COO-

Cocobetaine (CB)

Cocoamidopropylbetaine ( CAPB)

Uses : Amphoteric Surfactants

• Betaines are used in personal care products e.g. hair shampoos, liquid soaps, and cleansing lotions.

• All-purpose cleaning agents, hand dishwashing agents, and special textile detergents..

Nonionic Surfactants

Nonionic Surfactants

Water Solubility of NonionicsReason

Cloud Point

Effect of moles of EO on Cloud Points of Nonionic

Influence of Cloud Point on Soil Removal

HLB –Hydrophilic Lipophilic Balance

HLB is a means of expressing the hydrophilic property of surfactants in figures

HLB ValueSignificance

HLB Value 1 2 3 4 5 6 7 8 9 1011 12 13 14 15 16 17 18

Use

Water in oil emulsifier

Oil in water Emulsifiers

 

Wetting AgentsDetergent

s

 

 

Solubilizer

HLB According to Griffin (only for PEG types)

substantive to skin and hair

HLB = 20 ( 1 – SV / AV ) Where S V = Sap value of ester of polyhydric alcohol AV = Acid value of fatty acid used

Calculation of HLB value of PEG-7-glyceryl-cocoate

AV of cocofatty acid = 265 mg KOH/g SV of PEG-7-glyceryl-cocoate = 95

HLB = 20 ( 1 – 95 / 265 ) = 12.8

HLB According to Griffin (only for polyhydric alcohol types)

HLB = 7 + m * Hh + n * Hl where

• m - number of hydrophilic groups in the molecule• Hh - Value of the hydrophilic groups• n - Number of lipophilic groups in the molecule• Hl - Value of the lipophilic groups

HLB According to Davis

Ex : Calculation of HLB of SLES

Formula of SLES : CH3(CH2)11O (CH2CH2O)2SO3Na

HLB = 7 + (1 x 1.3 + 2 x 0.33 + 38.7)+(12 x - 0.475) = 42

Nonionic SurfactantsProperties

• Cleansing agent in detergents

• Emulsifying agents household & I & I formulations

• Wetting agents in textile processing, agrochemical formulations

Nonionic SurfactantsApplications

Thank you