Finely ground ammonium carbonate was dispersed in the polymer solution, which was then added to 200 ml of oil (either corn oil, castor oil, or mineral oil) containing 2% w/v surfactant (Span 20, 40 or 80).
The microcapsules containing ammonium carbonate were lyophilized to remove the core.
Ammonium carbonate was ground for a total of 6 hours, taking samples hourly from 3 hours.
The polymer and ammonium carbonate concentrations in each solvent were kept constant at 1.
Although a large population of discrete spherical capsules was formed with the acetonitrile/corn oil system, methods to reduce aggregate formation, increase microcapsule yield, and improve the encapsulation efficiency of ammonium carbonate were necessary.
The 5% w/v loading of ammonium carbonate was the highest limit before undue settling or flocculation of core material particles occurred in the polymer solution.
Ammonium carbonate particles were not found to be adhered to the surface, implying efficient encapsulation of core material.
Phase separation of PLGA, and encapsulation of the coacervate around ammonium carbonate particles was successful, proving the compatibility of interfacial energies and surface properties of the polymer droplets and hydrophilic core material in accordance with Arshady (1990) .
The effects of adding surfactants were studied to increase ammonium carbonate dispersion for improving encapsulation efficiency, and for reducing the microcapsule diameters below 10 X [10.
This probe had a higher shear design compared to the double-ringed emulsion probe, allowing better dispersion of both ammonium carbonate and coacervate droplets.
These could form during the coating of ammonium carbonate particles by coacervate droplets, showing areas of fusion of the capsule wall.