Effect of electrolyte in silicone oil-in-water emulsions stabilised by fumed silica particles.
Partially hydrophobised fumed silica particles are used to make silicone oil-in-water emulsions at natural pH of the aqueous phase. The stability and rheological properties of the emulsions and suspensions are studied at NaCl concentrations in the range 0-100 mM. It is found that all emulsions are very stable to coalescence irrespective of the NaCl concentration. However, a strong effect of electrolyte on the creaming and rheological properties is observed and linked to the particle interactions in aqueous suspensions. The creaming rate and extent are large at low electrolyte concentrations but both abruptly decrease at salt concentrations exceeding the critical flocculation concentration of the suspension (approximately 1 mM NaCl). The drastic improvement of the stability to creaming is attributed to the formation of a visco-elastic three-dimensional network of interconnected particles and emulsion droplets.
Horozov
Tommy S
TS
Surfactant & Colloid Group, Department of Chemistry, University of Hull, Hull, UK HU6 7RX. t.s.horozov@hull.ac.uk
Binks
Bernard P
BP
Gottschalk-Gaudig
Torsten
T
D004573:Electrolytes / Q000737:chemistry*; D004655:Emulsions; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D009994:Osmolar Concentration; D010316:Particle Size; D012212:Rheology; D012822:Silicon Dioxide / Q000737:chemistry*; D012827:Silicone Oils / Q000737:chemistry*; D012965:Sodium Chloride / Q000737:chemistry*; D013499:Surface Properties; D013997:Time Factors; D014867:Water / Q000737:chemistry*
D004573:Electrolytes; D004655:Emulsions; D012827:Silicone Oils; D014867:Water; D012965:Sodium Chloride; D012822:Silicon Dioxide