Polydisperse double emulsion, corresponding monodisperse double emulsion and method for preparing the monodisperse emulsion

A fractionatable stable double emulsion, having a polydispersity greater than 30%, of the water-in-oil-in-water type, consisting of 50 to 95% by weight, with respect to the total weight of the double emulsion, of droplets of a monodisperse inverse emulsion Ei dispersed in a continuous aqueous phase;

• the monodisperse inverse emulsion Ei having a polydispersity of up to and including 30%;
• the continuous aqueous phase comprising an alginate thickening agent at 1 to 10% by weight with respect to the total weight of the continuous aqueous phase;
• a water-soluble sequenced copolymer of ethylene oxide and propylene oxide as surfactant;
• and an osmotic pressure balancing agent;
• the emulsion Ei having a viscosity up to and including the viscosity of the continuous aqueous phase and consisting of 50 to 95% by weight, with respect to the total weight of Ei, of droplets of an internal aqueous phase dispersed in an oily phase;
• the internal aqueous phase comprising at least one hydrophilic active substance;
• the oily phase comprising polyglycerol polyricinoleate as surfactant;
• the concentration of balancing agent being sufficient to ensure osmotic balance between the aqueous phase of the emulsion Ei and the continuous aqueous phase,
• wherein the formula of the sequenced copolymer is:
• H—(OCH2CH2)a—(O—CH(CH3)—CH2)b—(OCH2CH2)a—OH (I)
• in which
• a is an integer between 50 and 120;
• and
• b is an integer between 20 and 100, and
• wherein the continuous aqueous phase comprises 1 to 5% by weight, with respect to the total weight of the continuous aqueous phase, of alginate, as a thickener;
• and 3 to 10% by weight with respect to the total weight of the continuous aqueous phase of the sequenced polymer of said formula (I), as a surfactant.