Coalescence flocculation assessment

The physical instability of emulsions involves creaming, flocculation, coalescence, or breaking, whereas the chemical instability can be a result of hydrolysis of the stabilizing moieties. In order to assess the stability of the emulsion, heating and freezing cycles and centrifugation and steam sterilization can be employed. 

Assessment and Prediction of Creaming, Sedimentation, Flocculation, and Coalescence of Formulations... 

The above measurements should be supplemented by particle size distribution measurements of the diluted dispersion (ensuring that no floes are present after dilution) to assess the extent of Ostwald ripening and/or coalescence. Another complication may arise from the nature of the flocculation, however. If the latter occurs in an irregular fashion, so as to produce strong and tight floes, //(o) may... 

Following the same strategy, the formation and stability of W/C emulsions was assessed in the presence of a PEO-fc-PFOA copolymer (M p o = 2000 g/mol and M pfoa 31,000 g/mol) [40], Note that the hydrophilic/C02-philic balance (HCB) was lower, and the Af of the copolymer was higher compared to the previous study. The observation of a W/C emulsion was reported from 25°C and 143 bar while flocculation or coalescence of dispersed water phase slowly occurred upon stopping of the stirrer. Notably, the formation of a W/C emulsion was reported at the cloud point pressure of the copolymer in a binary polymer/C02 mixture. 

The above trend depends on the extent of flocculation relative to Ostwald ripening. Therefore, following ap and with storage time requires knowledge of Ostwald ripening and/or coalescence. Only in the absence of this latter breakdown process can one use rheological measurements as a guide of assessment of flocculation. 

To characterize emulsion systems, it is necessary to obtain fundamental information on the liquid/liquid interface (e.g. interfacial tension and interfacial rheology) and properties of the bulk emulsion system, such as droplet size distribution, flocculation, coalescence, phase inversion and rheology. The information obtained, if analyzed carefully, can be used for the assessment and (in some cases) prediction of the long-term physical stability of the emulsion. 

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