Effects of surfactants on crystallization of ethylene glycol distearate in oil-in-water emulsion

Ethylene glycol distearate (EGDS) was forced to crystallize as thin platelet in order to obtain a pearlescent effect. This was possible by performing a cooling surface crystallization in oil-in-water emulsion with the presence of an emulsifier. Under stagnant conditions, nucleation events and growth of faceted crystals in the oil phase were in situ monitored under microscope. After a first primary nucleation of dendritic crystals, a second population of faceted crystals arose by secondary nucleation and seemed to be the prevailing population. In a stirred vessel, the platelet shape of EGDS crystals was driven by the surfactant choice. Only a non-ionic surfactant, located at the liquid interface was supposed to interact with EGDS during the development of the crystals favouring a platelet habit. The nature of the interaction was not yet established. Moreover, the mastery of the platelet shape was lost when the amount of non-ionic surfactant relatively to the EGDS was decreased. This underlined the importance of the non-ionic surfactant for the obtaining of desired shape. The different physical qualities of crystals produced allowed us to confirm relationships between EGDS particle features with their effect of pearlescence of a cold pearl blend.