How to generate oil-in-water and water-in-oil capsules and flat membranes of controlled thickness? 

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Reference: Tuneable thickness barriers for composite o/w and w/o capsules, films, and their decoration with particles. D. Z. Gunes; M. Pouzot; M. Rouvet; S. Ulrich; R. Mezzenga; Soft Matter, 2011, 7, 9206; DOI: 10.1039/c1sm05997a.

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In this paper, a generation method of oil in water and water in oil capsules and flat membranes of controlled thickness is presented. This method is based on the interfacial complexation between chitosan and anionic phosphatidic fatty acids (PFacidYN). Thanks to surface tension measurements using an automatic drop tensiometer (TRACKER™ by TECLIS), it has been shown that the simultaneous presence of both species at the interface has a striking effect on the value of surface tension, which drops below 3 mN/m within a time of the order of 3 min. This is 20 times more rapid than for PFacidYN alone, and for the case of the chitosan alone, surface tension does not reach values below 20 mN/m, which demonstrates a rapid formation of the first layers of the interfacial membrane. Finally, examples of membranes decorated with uncharged polystyrene particles (diameter of 3µm) are presented, opening thus the road to various application.

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TECLIS product: TRACKER™ automatic drop tensiometer

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Key words: Microfluidic, oil in water/water in oil capsules, membranes, complexation,  interfacial tension, shear rheology, adsorbed microparticles.