Surfactants

By Sachin Patel

1. Surfactants SACHIN PATEL

2. Surfactants Surface Acting Agent Reduces Surface Tension

3. Definition Surface tension: The molecules at the surface do not have other molecules on all sides of them and therefore are pulled inwards. This creates some internal pressure and forces liquid surfaces to contract to the minimal area. Surfactants: are substances that absorb to surfaces or interfaces, causing a marked decrease in the surface tension. Surfactants – Surface Active Agents

4. Surfactant structure All surfactants are characterized by having two regions in their molecular structure: A) a hydrophobic group , such as a hydrocarbon chain, that has no affinity for aqueous solvents B) a hydrophilic group that has an affinity for water. A molecular or ion that possesses this type of structure is termed amphipathic ( amphiphilic ).

5. AIR WATER These molecules preferentially position themselves at the water-organic interface due to energetic effects – they are surface active! e.g. Stearic Acid: CH 3 -(CH 2 ) 16 COOH

6. • Low molecular mass surfactants  Nonionic  Ionic  Amphoteric • Polymeric surfactants  Synthetic  Natural Classification of surfactants Dependent on the molecular composition and the nature of dissociation of their polar head groups the surfactants are classified as ionic (cationic, anionic, amphiphilic ) or nonionic.

7. Alkylpolyoxyethylenes Spans Tweens Nonionic surfactants C n EO m

8. Tweens Spans 85 80 60 85 80 60 Non-ionic surfactants Polyhydric alcohol:Tween , Span Polyoxyethylene Pluronic ( Poloxamer ) Sucrose esters (SE) Non- ionics : Can be tailored to specific applications (e.g. detergency, wetting agent,

9. 2.Ionic surfactants (a) Anionic (b) Cationic Diffuse electric layer sodium dodecyl sulfate dodecyl trimethyl ammonium chloride

10. Salts of higher fatty acids (soaps) Sodium dodecyl sulfate (SDS) (Sodium lauryl sulphate (SLS)) (widely used to produce o/w emulsions). Sodium glycocholate Sodium taurocholate Alkylbenzene sulfonates (detergents) Sodium Oleate : CH 3 (CH 2 ) 7 CH=CH(CH 2 ) 7 COO - Na + Sodium Dodecylsulphate : CH 3 (CH 2 ) 11 SO 4 - Na + Sodium Dodecylbenzenesulphonate : CH 3 (CH 2 ) 11 C 6 H 4 SO 3 - Na + Sodium Stearate : CH 3 (CH 2 ) 16 COO - Na + Anionic surfactants

11. 3 . Amphoteric surfactants (a) Natural soaps ( alkylcarboxylates ), Lipids

12. (b) Betaines AMPHOLYTICS : Dodecyl betaine : C 12 H 25 N + (CH 3 ) 2 (CH 2 COO - )

13. Properties of surfactants Critical micelle concentration (CMC) Hydrophile Lipophile Balance (HLB) HLB =20*M(hydrophilic) /M(surfactant)

14. Increasing concentration of surfactant in water slowly forming a layer on the surface and eventually forming micelles at or above the CMC CMC:concentration of surfactants at which it begin to form micelles. Critical micelle concentration (CMC)

15. Hydrophile-lipophile balance ： surfactants contain both hydrophilic groups and lipophilic groups with one or the other being more predominant, t he hydrophile-lipophile balance (HLB) number is used as a measure of the ratio of these groups. It is a value between 0-40 defining the affinity of a surfactant for water or oil. HLB value of nonionic surfactants ranges from 0-20. HLB numbers >10 have an affinity for water (hydrophilic) and number <10 have an affinity of oil ( lipophilic ). hydrophilic lipophilic HLB 0 10 20 Hydrophile-lipophile balance (HLB)

16. Calculation of HLB Values of Surfactant Mixtures The HLB values of the surfactant mixtures were calculated according to the following equation: where C1,C2,C3 are the percent of component proportion and HLB1,HLB2,HLB3 are the HLB values for the each component (23).

17. Micellar Structure and Shape (a) Ionics inner core - liquid phase hydrocarbon Shell diffuse electric double layer (b) Nonionics inner core - liquid phase hydrocarbon Shell

18. Micelle

19. M icell

20. The mechanism for solubilization Solubilization is the process of incorporation of the solubilizate into or onto the micelles.

21. Applications of Surfactant Cleaning/Detergents (40%), Textiles, Cosmetics, Paper Production, Paint, Food, Mining (Flotation)...... Surfactant production per year: ~40 billion tons

22. An adhesive * is a compound, or a mixture of compounds, intended to assist cleaning. The term is often used to differentiate between soap and other chemical surfactants used for cleaning purposes * is a compound that adheres or bonds two items together. An emulsifier * (also known as an emulgent or surfactant ) is a substance which stabilizes an emulsion. Detergent

23. An ink is a liquid containing various pigments and/or dyes used for colouring a surface to render an image or text. Ink is used for drawing or writing with a pen or brush. * Fabric softener * is used to prevent static cling and makes the fabric softer.

24. Paint Anti-fogs Shampoos Toothpastes Oil dispersants Wetting Ski Wax Snowboard Wax Foaming Defoaming Quantum dot coating Biocides (Sanitizers) Hair Conditioners (after shampoo)

25. Thank You. . .