5. Cationic Surface Active Agents
Cationic surface active agents agents are
those substance which dissociate in water to
give postively charged ions.
e.g. Cetyl trimethyl ammonium chloride,
Cetyl pyridinium choride,
Octadecyl ammonium Chloride.
6. Anionic Surface Active Agents
Anionic Surface Active agents are sodium salts of higher fatty acids
such as sodium palmitate
Sodium stearate
Sodium oleate
The Salts of sulphonic acids of high molar mass acts as anionic
surfactants.
7. Non ionogenic Surface Active Agents
Non ionogenic surface active agents are those substance whose
molecules cannot undergo dissociation. When an alcohol having a high
molar mass reacts with several molecules of ethylene oxide, a non
ionogenic surfactant is obtained.
Some other examples are ethoxylate,alkoxylates and cocamides.
These surfactants are a close second widely, used in a range of
cleaning,personal care and disinfactant products as well as industrial
proceses.
8. • Amphoteric Surface Active Agents
These surfactants have a dual charge on their hydrophillic end,both
positive and negative. The dual charge cancel each other out creating
a net charge zero,reffered to as Zwitterionic.
The pH of any given solutions will determine how amphoteric
surfactant react. In acidic solution the amphoteric surfactants
become positively charged and behave similarly to cationoic
surfactants. In alkaline solutions, they develop a negetive charge
simillar to anionic surfactant.
Anionic surfactants are often used in personal such as shampoos and
cosmetics.
Examples: betaines and amino oxides.
9. Micelles
The Micelles or Ionic micelles as defined by James William Mc Bain are
the Clusters or aggregates formed in solution by colloidal electrolytes.
The micelles may contain hundered or more ions clumped together
with a considerable number of water molecules.
According to modern concepts micelles may be defined to be the
aggregate of long chain diphilic surfactant Molecules or ions formed
spontaneously in their solutions at a definite concentration.
Micelles are formed, by the cooperative binding of monomers to one
another.
12. Thermodynamics Of Micellization
Hydrophobic interactions can be regarded to be the
thermodynamic driving force of micellization. The Hydrocarbon
part of a diphilic molecule gets forced out of the aqueous medium
to avoid contact of the Chain with water consists of a liquid
Hydrocarbon ( combined closely packed hydrocarbon chains), while
the external part which faces the aqueoues solution has polar
groups.
Micellization is a spontaneous process i.e. The change in free
energy ,∆G=∆H-T∆S becomes less then zero. The main contribution
to the value of ∆G is made not by the change in enthalpy,Which is
insignificant in magnitude but by the change in the entropy ,T∆S.
The removal off hydrocarbon chains of the diphilic molecules from
water into the micelles disorders the structure of water and thus
the entropy of the system increases (∆S>0).
17. Factors Affecting CMC
•Structure Of The Amphiphiles
•Ionic Surfactants
•Bulky Hydrophobic/Hydrophilic Groups
•Presences Of Aditives
•Experimental Conditions Like Temp.
