Micro encapsulation

1. COACERVATION- PHASE
SEPERATION TECHNIQUE IN
MICROENCAPSULATION
By:
N. Sivanaga Tejaswini
Y14PH0505
CLPT

2. CONTENTS…
 Introduction
 Microencapsulation techniques
 Coacervation-phase separation
process
 Steps in coacervation-phase
separation
 Techniques used in coacervation-
phase separation
 Conclusion

3. INTRODUCTION:
 Microencapsulation is the packaging of small
particles of solid, liquid or gas, also known as core,
within a secondary material, also known as shell or
coating to form small microparticles.

4. MICROENCAPSULATION
TECHNIQUES:
1. Air suspension process
2. Coacervation-phase separation
process
3. Pan coating
4. Solvent evaporation process
5. Spray drying or Spray congealing
6. Interfacial polymerization
7. Multi orifice centrifugal process.

5. COACERVATION-PHASE SEPARATION
PROCESS:
 Coacervation means the separation of a liquid or
phase when solution of two hydrophilic colloids
are mixed under suitable conditions.
 In this method, the three immiscible phases of
core material, solvent and coating material are
formed followed by deposition of coating material
on the core.
 The coating material is dissolved in a suitable
solvent and the core material is uniformly
dispersed in the solution of the coating material.
 Then the coating material is phased out of its
solution which starts getting deposited on the
particles of the core material.

6. STEPS IN COACERVATION:
Coat formation during coacervation-phase separation
process consists of three steps carried out under continues
agitation:
STEP:1 Formation of three immiscible chemical phases
(vehicle, core and liquid coating).
STEP:2 Deposition of the coat material
STEP:3 Rigidisation of the coat material.

7. STEP:1 Formation of three
immiscible phases
A Liquid manufacturing vehicle phase, a core material
phase and a coat material phase.
 To form the three phases, the core material is
dispersed in a solution of the coating polymer, the
solvent for the polymer being the liquid manufacturing
vehicle phase.
 The coating material phase, an immiscible polymer in a
liquid state, is formed by utilizing one of the methods of
coacervation phase separation.

8. STEP:2 Deposition of the coating
material:
 This is accomplished by controlled, physical mixing of
the coating material and the core material is the
manufacturing vehicle,
 Deposition of the liquid polymer coating around the core
material occurs if the polymer is adsorbed at the
interface formed between the core material and the
liquid vehicle phase, and this adsorption phenomenon
is a prerequisite for the coating.
 The continued deposition of the coating material is
promoted by a reduction in the total free interfacial
energy of the system, by decreasing of the coating
material surface area during coalescence of the liquid
polymer droplets.

9. STEP:3 Rigidisation of the coating
material
The process involves rigidizing the coating usually by
thermal, crosslinking or desolvation technique to
form a self-sustained microcapsule.

10. TECHNIQUES USED IN
COACERVATION
1. Temperature change
2. Incompatible polymer
addition
3. Non-solvent addition
4. Salt addition
5. Polymer polymer
interaction

11. TEMPERATURE CHANGE
Under proper polymer concentration,
temperature and agitation conditions the liquid
polymer droplets coalesce around the dispersed
core material particles, thus forming the
embryonic microcapsules.
EXAMPLE:
Core material : N- amino acetophenol
Coating material : Ethyl cellulose
Solvent : Cyclohexane

12. INCOMPATABLE POLYMER
ADDITION
Liquid phase separation of a polymeric coating
material and microencapsulation can be accomplished
by utilizing the incompatibility dissimilar polymers
existing in a common solvent.
EXAMPLE:
Core material: Methylene blue HCL
Coat material: Ethyl cellulose
Solvent : Toulene

13. NON-SOLVENT ADDITION
A Liquid that is a non-solvent for a given polymer is
added, to a solution of the polymer to induce the phase
separation, as indicated by the general phase diagram.
The resulting immiscible, liquid polymer can be utilized to
microencapsulation of an immiscible core material.
EXAMPLE:
Core material: Methylscoplamine
Coat material: Cellulose acetate
Solvent : Methyl ethyl ketone
Non-solvent : Isopropyl ether

14. SALT ADDITION
Soluble inorganic salts are added to aqueous
solutions of water soluble polymers to cause phase
separation.
EXAMPLE:
Core material: Vitamin A
Coat material: Pig gelatin
Salt : Sodium sulphate
Solvent : Water

15. POLYMER-POLYMER
INTERACTION (COMPLEX
COACERVATION)
The interaction of oppositely charged poly electrolytes
can result in the formation of a complex having reduced
solubility and phase separation occurs.
Complex coacervation process consists of three steps:
1. Formation of an O/W emulsion
2. Formation of the coating
3. Stabilization of the coating.
EXAMPLE:
Core material: Methyl salicylate
Coat material: Gelatin or Gum acacia
Solvent : Water

16. CONCLUSION:
 Microencapsulation process involves basic
understanding of the general properties of
microcapsules such as nature of the core and the
coating material, the stability and the release
characteristics of the coated materials and its methods.
 Microencapsulation technique is employed for the
production of:
 Sustained release or prolonged action of medications.
 Taste masked chewable tablets, suspensions and
powders.
 Stabilization of oxidation process.
 Reduction of volatility.
 Reduced gastric irritation.

17. REFERENCES:
 “The Theory And Practice Of Industrial
Pharmacy”, by Leon Lachman and Herbert
Liebermann; 3rd edition, Indian Edition; Varghese
Publishing House, Bombay; 1987; Page No: 412-
429
 http://www.google.com