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SURFACTANTS IN SOLUTION

SURFACTANTS IN SOLUTION. Classification of Surfactants. Anionic Cationic Zwitterionic Nonionic. Sodium dodecylsulfate (SDS). Cetylpyridinium bromide. Dipalmitoylphosphatidylcholine (lecithin). Polyoxyethylene(4) lauryl ether (Brij 30). 4 nm. Surfactant Aggregates. Normal micelles.

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SURFACTANTS IN SOLUTION

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  1. SURFACTANTS IN SOLUTION

  2. Classification of Surfactants • Anionic • Cationic • Zwitterionic • Nonionic Sodium dodecylsulfate (SDS) Cetylpyridinium bromide Dipalmitoylphosphatidylcholine (lecithin) Polyoxyethylene(4) lauryl ether (Brij 30)

  3. 4 nm Surfactant Aggregates Normal micelles Unimers cylindrical spherical Inverted hexagonal phase Reverse micelles Bilayer lamella

  4. 14  12 10 8 CMC 6 4 2 0 0 Surfactant concentration 1 Critical Micelle Concentration CMC • Below CMC only unimers are present • Above CMC there are micelles in equilibrium with unimers

  5. 14 Concentration unimers 14  Osmotic pressure 12 12 10 10 8 8 CMC 6 CMC 6 micelles 4 4 2 2 0 0 0 1 Surfactant concentration 0 1 Surfactant concentration 14 Isc 12 Light scattering 10 8 CMC 6 4 2 0 0 1 Surfactant concentration Solution Properties

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

  7. 14 Solubility 12 10 8 CMC 6 4 2 0 0 Surfactant concentration 1 Solubility Effects • Solubility of a poorly soluble compound increases as a result of solubilization in the micelles

  8. 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; 880+ 270 = 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

  9. Important to remember !

  10. 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

  11. 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 15/18 12.5 • White wax 12 x 1/18 0.7 • Lanolin 10 x 2/18 1.1 • Total required HLB 14.3

  12. 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)

  13. 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 0.4 + 14.9 x 0.6 = 10.8

  14. 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

  15. 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

  16. Shampoo

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

  18. cyclomethicone Propylene Glycol Dicaprylate/Dicaprate

  19. 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

  20. 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).

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

  22. Cream

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