PH adjustment

• dilution and/or temperature change

• addition of an incompatible or non-wall-forming polymer

• three wall-forming polymers

III A single wall-forming polymer soluble in an organic liquid

• addition of a miscible liquid, a non-solvent for the polymer

• change of temperature

• addition of an incompatible or non-wall-forming polymer

• evaporation with a miscible liquid, a non-solvent for the polymer

• evaporation with an immiscible polar liquid, a non-solvent for the polymer

• evaporation or removal with an immiscible organic liquid, a non-solvent for the polymer

IV Two wall-forming polymers soluble in organic liquids

V One wall-forming polymer soluble in water and one soluble in an organic liquid

While emphasis is placed on the above classification, it would appear that the properties of the core material are not important. This is not true as the core, whether a solid, a mixture of solids, a liquid, a solution, a suspension or an emulsion, for example, may alter or inhibit the process of coacervation-phase separation. A suitable process must be selected in order to obtain a satisfactory product in terms of maximum utilization of the core and appropriate characteristics of the product.

In many cases it is not necessary to have a core present - empty microcapsules are formed. In other cases microcapsules are not readily formed unless there is a core present to promote deposition of the polymer. Only a few procedures which do not pertain to pharmacy will be described in order to exemplify different procedures or materials. Coacervation-phase separation is also used extensively in a number of other fields, such as photography, agriculture, food and biology.

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