Research On Preparation Of Functional Materials In A Pickering Emulsion

When some fine solid powders were mixed with water and an oily solvent, a solid-stabilized emulsion (often referred to as a Pickering emulsion) could be obtained even if no surfactants were used. Recently, Pickering emulsions have been found to be a suitable medium in many frontiers, such as the preparation of functional materials, catalytic reaction. With the droplets of a Pickering emulsion as templates, MgO/Mg(OH)₂ hollow microspheres, MgO hollow microspheres and water-containing Mg(OH)₂/PS composites were prepared. The structure and performance of the products were characterized.MgO/Mg(OH)₂ hollow microspheres were prepared with the droplets of a Pickering emulsion as templates. MgO/Mg(OH)₂ microspheres were formed via a hydration reaction of MgO at the oil/water interfaces. The products were characterized by SEM, XRD and BET measurement. A possible mechanism of an interfacial hydration reaction was proposed. The images of SEM showed that the MgO/Mg(OH)₂ microspheres had an average diameter of 62μm. During the hydration, part of the MgO particles turned into Mg(OH)₂, and clinged to the surface of MgO. MgO/Mg(OH)₂ hollow microspheres formed. The controlled-release formulation of avermectins microcapsule encapsulated with MgO/Mg(OH)₂ hollow microspheres was studied. The results showed that, avermectin in the microcapsules release quickly at beginning and stablely later. Avermectins microcapsules displayed good controlled-release characteristics and satisfied the necessary prerequisites for prolonged control period.After calcinations, MgO/Mg(OH)₂ hollow microspheres turned into MgO hollow microspheres. The MgO microspheres were of periclase structure and had a specific surface area of 28 m²/g. The surfaces of the MgO microspheres were made up of nanoflakes with an average thickness of 65 nm. The adsorptive ability of the MgO microspheres to Ni²⁺ was investigated. The effect of the treatment agent's dosage, temperature, mixing time, stirring time and settling time on the removal ratio was analyzed. The results showed that, the MgO microspheres had a similar adsorptive ability to Ni²⁺ to that of MgO nanoparticles, while were more easily separated from the aqueous solution by simple filtration procedure. With the dosage of 0.4g/L, the concentration of Ni²⁺ decreased to 1.7%Water-containing Mg(OH)₂/PS composites were prepared by a polymerization reaction with the droplets of a Pickering emulsion as templates. The results showed that the Mg(OH)₂/PS composites had holes with an average diameter of about 155μm, which served as reservoirs for water. With the increase of polymerization temperature, the amount of water in the composites decreased. The mechanical properties of the water-containing Mg(OH)₂/PS composites decreased, however, the oxygen index of the composites was much higher than that of the ordinary Mg(OH)₂/PS composites, due to the dual flame retardant effect of water and Mg(OH)₂。...