solubilization,Solubility and Micelle Formation

ppt of solubilzation, solubility, factor effecting solubility,surfactant and micelle formation.

by Sanjay Kumar (hamdard University)

1. SOLUBILIZATION PRESENTED BY “SANJAY KUMAR” DE-073 SUBMITTED TO : Dr. TAHMINA ADNAN LECTURER AT HAMDARD UNIVERSITY, FACULTY OF PHARMACY

2. SOLUBILIZATION The process whereby something becomes  soluble or more  soluble.

3. MECHANISM OF SOLUBILIZAtion Break up of solute-solute intermolecular bonds. Break up of solvent-solvent intermolecular bonds. Formation of cavity in solvent phase large enough to accommodate solute particles. Transfer of solute into cavity of solvent phase. Formation of solute –solvent intermolecular forces.

4. Solubilty IN QUANTITATIVE WAY : Concentration of solute ion a saturated solution at a certain temperature. IN QUALITATIVE WAY : Spontaneous interaction of two or more substances to form homogenous molecular dispersion

5. FACTORS AFFECTING SOLUBILITY There are three main factors that control solubility of a solute. Temperature, Nature of solute or solvent, Pressure.

6. FACTORS TEMPERATURE EXOTHERMIC PROCESS solubility decreases with increase in temperature and vice versa ENDOTHERMIC PROCESS solubility increases with increase in temperature and vice versa. NATURE OF SOLUTE AND SOLVENT A polar solute dissolved in polar solvent. Solubility of a non-polar solute in a solvent is large. A polar solute has low solubility or insoluble in a non-polar solvent PRESSURE An increase in pressure increases of solubility of a gas in a liquid. The relationship between pressure and solubility can be summarized by combining Le Chatelier's principle and Henry's Law .

7. surfactant STRUCTURE OF SURFACTANTS Surfactant molecules are usually organic compounds that contain hydrophobic groups or " tails " and hydrophilic groups or " heads ." Surfactants are chemical species that act as wetting agents to lower  the surface tension  of a  liquid  and allow for increased spread ability EXAMPLE Sodium stearate 4-(5-dodecyl) benzenesulfonate alkyl ether phosphates benzalkaonium chloride ( BAC)

8. TYPES OF SURFACTANTS There are four types of surfactants. Anionic, Nonionic, Cationic, Zwitter ( amphoteric ) ion.

9. Anionic surfactant Have a negatively charged end of the molecule that gives it hydrophilic part . These negatively charged parts of the molecules are usually sulfonates , sulfates, or carboxylates . Are ionic , made up of two ions positively charged(metal, ion )and a negatively charged(organic ion) EXAMPLE: sodium alkyl benzene sulfonates , sodium stearate (a soap), and potassium alcohol sulfates

10. Nonionic surfactant have no ions . derive their polarity from having an oxygen rich portion of the molecule at one end and a large organic molecule at the other end. EXAMPLE: alcohol ethoxylates , nonylphenoxy polyethylenoxy alcohols, and ethylene oxide/propylene oxide block copolymers

11. Cationic surfactant Are positively charged molecules usually derived from nitrogen compounds . Not commonly used as cleaning agents . Many cationic surfactants have bactericidal or other sanitizing properties. Cationic surfactants are usually incompatible with anionic surfactants, because they will react with the negatively charged anionic surfactant to form an insoluble or ineffective compound.

12. Amphoteric ( zwitter ) ionic surfactant Change their charge with pH . They can be anionic, nonionic, or cationic depending on pH.   For the amphoteric surfactants the charge of the hydrophilic part is controlled by the pH of the solution. They can act as anionic surfactant in an alkalic solution or as cationic surfactant in an acidic solution .

13. micelle Are made out of amphipathic molecules. A micelle is a ball that forms when amphipathic molecules are put in a liquid. The liquid can be polar like water or non-polar like butane or octane. Micelles will form because only one end of the amphipathic molecules will be compatible with the liquid. 

14. Micelle formation In the aqueous system the high interfacial energy between the water molecules and the hydrocarbon chains of the surfactant is the primary factor in the process, while in a nonpolar system the attractive interaction between the polar parts serves as the force governing the association process. The micellization in aqueous solutions may be perceived as a phase separation that is modified through geometrical restrictions, while the corresponding phenomenon in oils is a chemical equilibrium similar to that of alcohols in such media. The consequence of this difference is that the process in water is highly cooperative and the designation of a critical micellization concentration ( cmc ) is justified. In the nonpolar environment, on the other hand, the association process is gradual and the term cmc is not warranted. In this case the interactions leading to the micellization are amenable to analysis by spectroscopic methods.

15. Types of micelle Following are three types of micelles Spherical micelle, Rod shaped micelle, Laminar micelle.

16. Spherical micelle Amphipatic can form bilayers that sandwich the tails in the middle, or they can form spherical micelles. Phospholipids are amphipathic molecules that contain two water-fearing tails. Phospholipids prefer to form bilayers . Fatty acids have only one water-fearing tail, so forming a micelle is easier and more stable for them

17. Rod shaped micelle Monomers are arranged in rod shape Rod formation is primarily governed by the characteristic Gibbs free energy of rod formation,  ΔG   rod . Geometrically, a rod-shaped micelle consists of a central cylindrical part of hydrocarbon radius  r   c  and of more or less hemispherical parts at the ends of hydrocarbon radius  r   s . The model includes hydrophobic, electrostatic, and steric interactions.

18. Laminar micelle Are interconvertable . In this type of micelle monomers are arranged in laminar manner. They are form at higher concentration. Initially micelles are of spherical type but as the concentration increases towards higher side leads to formation of laminar micelle.