Dispersion interaction across fluid

There are three scenarios for the occurrence of a two-particle collision in a dispersion depending on the type of particle-particle interactions. (1) If the repulsive forces are predominant, the two colliding particles will rebound and the colloidal dispersion will be stable. (2) When at a given separation the attractive and repulsive forces counterbalance each other (the film formed upon particle collision is stable), aggregates or floes of attached particles can appear. (3) When the particles are fluid and the attractive interaction across the film is predominant, the film is unstable and ruptures this leads to coalescence of the drops in emulsions or of the bubbles in foams. 

Drug release from stearic acid-coated microspheres may occur by diffusion when microspheres come in contact with aqueous fluids in the G1 tract. This release may occur when water diffuses into the interior of the microsphere, and allows the drug to diffuse across the release coat of the microsphere to the exterior [82], In addition, stearic acid may act as an emulgent that regulates the rate of drug release from microspheres [83], After ingestion, the drug will disperse and dissolve upon contact with GI fluid, possibly by interactions between stearic acid and the suspension media [85],... 

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