19-12-2012, 02:33 PM
POLYMERIC MICELLES AND its IMPORTANCE
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Polymeric Micelles
Polymeric is an organic molecule and mostly of the compound is noncrystalline
Micelles are relatively small, spherical structures
Polymeric micelles are nano-sized particles that are made up of polymer chains and are usually spontaneously formed by self-assembly in a liquid
The micelles internally have a hydrophobic core and
externally a hydrophilic surface
How Are Micelles Formed
When the concentration of surfactant reaches a critical concentration, the hydrophobe of the surfactant will organize to form micelle.
In the micelle, the lipophilic hydrocarbon chains are orientated towards the interior of the micelle, leaving the hydrophilic groups on contact with the aqueous medium
Conventional Polymeric Micelle
These micelles are formed by hydrophobic interactions between the core segment and the corona region in the aqueous environment
One of the simplest amphiphilic block copolymer polymer ethylene oxide - propylene oxide - ethylene oxide , forms micelles as a result of1 hydrophobic interactions.
TYPES OF POLYMER USED
Micelle-forming amphiphilic copolymers can be either block copolymers (di, tri, or tetra) or graft copolymers
Eg: di copolymer
A graft copolymer is one which comprises a polymer chain as a backbone and another polymer chain as side ''grafted'' parts
Eg : N-phthaloylchitosan-g-polycaprolactone