Oil coating on hydrophilic surfaces from emulsions and under shear flow.
We study the formation of silicone oil coating on negatively charged hydrophilic surfaces via emulsion deposition. Cationic surfactants usually adsorb and form bilayers onto negative surfaces. As a result, direct emulsions stabilized with cationic surfactants are paradoxically poorly efficient at coating negative substrates. We show in this work an alternative and new method, still based on electrostatic attractions, to coat negative substrates. Our method consists of using emulsions stabilized with nonionic surfactants and of adding to the oil cationic additives that are non-water-soluble and of high molecular weight to minimize their solubilization in the micelles formed by the neutral surfactant. The positively charged droplets stick efficiently onto the substrates. They form monolayer and uniform coatings. We study the kinetics and the density of the resulting coating using a flow cell experiment. This technique allows us to finely analyze the influence of several physicochemical parameters.
Essafi
Wafa
W
Centre de Recherche Paul Pascal, Avenue Albert Schweitzer, 33600 Pessac, France.
Poulin
Philippe
P
Chiron
Stéphanie
S
Bavouzet
Bruno
B
D004655:Emulsions; D017022:Flow Injection Analysis; D006863:Hydrogen-Ion Concentration; D008823:Micelles; D017646:Organosilicon Compounds / Q000737:chemistry*; D012827:Silicone Oils / Q000737:chemistry*; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry; D013997:Time Factors
D004655:Emulsions; D008823:Micelles; D017646:Organosilicon Compounds; D012827:Silicone Oils; D013501:Surface-Active Agents