title: Optimizing organoclay stabilized Pickering emulsions.
abstract: Oil-in-water emulsions were prepared using montmorillonite clay platelets, pre-treated with quaternary amine surfactants. In previous work, cetyl trimethylammonium bromide (CTAB) has been used. In this study, two more hydrophilic quaternary amine surfactants, Berol R648 and Ethoquad C/12, were used and formed Pickering emulsions, which were more stable than the emulsions prepared using CTAB coated clay. The droplets were also more mono-disperse. The most hydrophilic surfactant Berol R648 stabilizes the emulsions best. Salt also plays an important role in forming a stable emulsion. The droplet size decreases with surfactant concentration and relatively mono-disperse droplets can be obtained at moderate surfactant concentrations. The time evolution of the droplet size indicates a good stability to coalescence in the presence of Berol R648. Using polarizing microscopy, the clay platelets were found to be lying flat at the water oil interface. However, a significant fraction (about 90%) of clay stayed in the water phase and the clay particles at the water-oil interface formed stacks, each consisting of four clay platelets on average.
authors.affiliation: School of Chemistry, Cantock's Close, University of Bristol, Bristol, UK.
authors.forename: Yannan
authors.initials: Y
authors.lastname: Cui
authors.forename: Mhairi
authors.initials: M
authors.lastname: Threlfall
authors.forename: Jeroen S
authors.initials: JS
authors.lastname: van Duijneveldt
mesh_terms: D000327:Adsorption; D001546:Bentonite / Q000737:chemistry*; D004655:Emulsions / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D009821:Oils / Q000737:chemistry; D010316:Particle Size; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D004655:Emulsions; D009821:Oils; D000644:Quaternary Ammonium Compounds; D013501:Surface-Active Agents; D001546:Bentonite