1. SURFACTANTS IN SOLUTION

2. Classification of Surfactants
Anionic
Cationic
Zwitterionic
Nonionic
Sodium dodecylsulfate (SDS)
Cetylpyridinium bromide
You will find many other examples of amphiphilic surfactants in the recommended literature
Dipalmitoylphosphatidylcholine (lecithin)
Polyoxyethylene(4) lauryl ether (Brij 30)

3. Surfactant Aggregates
Normal micelles
Unimers
cylindrical
spherical
Inverted hexagonal phase
Molecules of amphiphilic surfactants in solution self-assemble into various supramolecular aggregates. This slide shows typical changes in surfactant self-assembly and morphologies formed with decreasing water content in the system (water content decrease is shown by arrows)
Reverse micelles
Bilayer lamella
4 nm

4. Critical Micelle Concentration
CMC 2 4 6 8 10 12 14 1
Surfactant concentration
CMC 
Below CMC only unimers are present
Above CMC there are micelles in equilibrium with unimers
Critical micelle concentration (CMC) can be determined by surface tension measurements. Below CMC surfactant adsorbs on the surface and decreases surface tension. More surfactant we have below CMC less surface tension is. Above CMC the micelles are formed. All surfactant added in excess of the CMC incorporate in the micelles. Therefore surface tensions remains the same as at CMC.

5. Solution Properties Surfactant concentration CMC Concentration2 4 6 8 10 12 14 1
Surfactant concentration
CMC
Concentration
unimers
micelles 2 4 6 8 10 12 14 1
Surfactant concentration
CMC
Osmotic pressure 
Dependencies of various solution properties on surfactant concentration reveal a break upon crossing the CMC as a result of micelle formation. This underlies methods for determining CMC by measuring such properties as a function of the surfactant concentration. 2 4 6 8 10 12 14 1
Surfactant concentration
CMC
Isc
Light scattering

6. Solubilization
Spontaneous transfer of a compound insoluble in the bulk solvent into solution due to incorporation into the surfactant micelles
polar compound
Reverse micelles
non-polar compound
Normal micelles
amphiphilic compound

7. Solubility Effects
Solubility of a poorly soluble compound increases as a result of solubilization in the micelles 2 4 6 8 10 12 14 1
Surfactant concentration
CMC
Solubility
One method to characterize CMC of a surfactant in aqueous solution is to determine solubility of a water-insoluble dye as a function of surfactant concentration. Above CMC the dye is transferred into solution due to incorporation into the core of the micelles.

16. An example of an HLB value calculation
BRIJ ® 98 INCI name : oleth-20 is a 20 mole ethoxylate of oleyl alcohol
calculate the molecular weight of the 20 moles of ethylene oxide ( one mole ETO =44 );
20 x 44 = 880
add this number to the molecular weight of the oleyl alcohol;
= 1150 ( the mol. wt of BRIJ 98 )
What percentage of 1150 is 880 ?
880/1150 = 76.5%
76.5% divided by 5 = 15.3
15.3 is the HLB value of BRIJ 98

18. Important to remember !

20. HLB and Use of Surfactants
Amphiphilic surfactants are characterized by the hydrophilic-lipophilic balance (HLB): a relative ratio of polar and non-polar groups in the surfactant
HLB ca. 1 to 3.5: Antifoams
HLB ca. 3.5 to 8: Water-in-Oil Emulsifiers
HLB ca. 7 to 9: Wetting and spreading agents
HLB ca. 8 to 16: Oil-in-Water Emulsifiers
HLB ca. 13 to 16: Detergents
HLB ca. 15 to 40: Solubilizers
HLB is an arbitrary parameter. Sometimes it is determined experimentally, for example, using reverse phase chromatography. There are numerous methods of computing of HLB. More information on computing of HLB (including blends of surfactants and requred HLB) can be found in: M. Stoklosa and H. Ansel, Pharmaceutical Calculations, Williams & Wilkins, Baltimore, 1996.

22. Required HLB
HLB needed for emulsification of the oil phase. If there are several oil ingredients the required HLB is calculated as a sum of their respective required HLB multiplied by the fraction of each.
Calculate the required HLB for the oil phase of the following o/w emulsion: cetyl alcohol 15 g., white wax 1g. Lanolin 2 g, emulsifier (q.s.), glycerin 5 g. water 100 g.
Required HLB Fraction
(from reference)
Cetyl alcohol 15 x 15/
White wax 12 x 1/18 0.7
Lanolin 10 x 2/18 1.1
Total required HLB
HLB is an arbitrary parameter. Sometimes it is determined experimentally, for example, using reverse phase chromatography. There are numerous methods of computing of HLB. More information on computing of HLB (including mixtures of surfactants) can be found in: M. Stoklosa and H. Ansel, Pharmaceutical Calculations, Williams & Wilkins, Baltimore, 1996.

23. HLB of Surfactant Blend
Surfactant blends are commonly used to obtain desired emulsifying properties.
Span 60 (HLB = 4.7)
Tween 60 (HLB = 14.9)
Span 80 (HLB = 4.3)
Tween 80 (HLB = 15.0)
HLB is an arbitrary parameter. Sometimes it is determined experimentally, for example, using reverse phase chromatography. There are numerous methods of computing of HLB. More information on computing of HLB (including mixtures of surfactants) can be found in: M. Stoklosa and H. Ansel, Pharmaceutical Calculations, Williams & Wilkins, Baltimore, 1996.

24. What is the HLB of the mixture of 40 % Span 60 (HLB = 4
What is the HLB of the mixture of 40 % Span 60 (HLB = 4.7) and 60 % Tween 60 (HLB = 14.9)?
Sorbitan monostearate is an ester of
sorbitol and stearic acid (synthetic wax)
Polyoxyethylenesorbitan monooleate;
Sorbitan monooleate ethoxylate
HLB of mixture: 4.7 x x 0.6 = 10.8

26. In what proportion should Span 80 (HLB = 4. 3) and Tween 80 (HLB = 15
In what proportion should Span 80 (HLB = 4.3) and Tween 80 (HLB = 15.0) be mixed to obtain “required” HLB of 12.0?
4.3.(1-x) + 15.x = 12 x = 0.72
72 % Tween 80 and 28 % Span 80

28. Glycerol Monostearate
HLB value of 3.6~4.2
dissolves in hot grease, paraffine, ethanol, chloroform, acetone and aether, the material is widely used when producing of chocolate, margarine, ice cream, skin care balsam, cold cream, hair oil and drug ointment, also lubricant for plastic processing

36. Shampoo

37. Ingredients Isobutane Cyclomethicone Aluminum Chlorohydrate
Propylene Glycol Dicaprylate/Dicaprate
Lichen extract
Fragrance
Quaternium-18
Silica
Dimethiconol

38. cyclomethicone
Propylene Glycol Dicaprylate/Dicaprate

39. Facial Cleanser Aqua/Water Palmitic acid Myristic acid Lauric acid
Stearic acid
Potassium hydroxide
PEG-7 Glyceryl cocoate
PEG-150 Distearate
Glycerin
Sodium laureth sulfosuccinate
Limonene
Linalool
Zinc PCA
Propylparaben
Propylene glycol
Disodium EDTA
NaCl

40. Propylene glycol
propyl ester of p-hydroxybenzoic acid = propylparaben
zinc salt of 2-Pyrrolidone-5-Carboxylic Acid
PEG-7 Glyceryl cocoate
Polyoxyethylene glycol glyceryl cocoate (monococoate).

41. PEG-150 Distearate
Polyethylene glycol diester of stearic acid.
Sodium laureth sulfosuccinate

42. Cream