| Core-shell microspheres are widely given more concern recent years and they are used in most areas including photocatalysis,battery,gas storage and separation.The microsphere is an orderly assembly structure and its inorganic nano-materials are wrapped by a layer of polymer.Microemulsion polymerization is the best method to prepare core-shell structure from the point of the stability of preparation and particle size.The smallest size of modified silica and optimum grafting of modified silica can be prepared when KH570 is used as well as time is 2h,temperature is 50? and the mass percent of KH570 is 40wt.%.On the basis of solubilized water,the component of microemulsion and mass ratio among components on solubilized water are studied when microemulsion is researched by ternary phase diagram.The result shows that the maximum amount of solubili-zed water is 23.7%when the components are hexane,Tween-80 and pentanol as well as the mass ratio of hexane/Tween-80/pentanol is 15/9/6.Core-shell microspheres are prepared when microemulsion is as reaction zone and materials are used including modified silica,initiator,monomer and cross-linking agent.According to the single factor method,the effect of concentration of modified silica,the amount of initiator and concentration of monomer to water ratio on the number of core-shell microspheres are studied.Meanwhile,the effect of the mass ratio of acrylic acid to acrylamide,reaction temperature,crosslinking agent dosage,the concentration of salt and the temperature of water absorption on expansion ratio of microspheres are also researched.The results show that the yield of core-shell microsphere is most when modified silica is 3wt.%,the amount of initiator is 6wt.%,concentration of monomer to water ratio is 30wt.%,meanwhile,the expansion ratio of microspheres can increase to 5.5 within one hour when the mass ratio of acrylic acid to acrylamide is 9:1,reaction temperature is 40 ?,the temperature of water absorption is 40 ? and the mass percent of crosslinking agent is 0.1 wt.%.Expansion ratio of microspheres can not decrease when the concentration of salt exceeds to 50000mg/L and these microspheres perform best in salt resistance.Core-shell microspheres are tested by all kinds of characterization and results are obtained.The result of Fourier transfer-infrared spectrometry(FTIR)shows that the structure of synthetic product is the same as the structure of target product.The core-shell structure of microspheres is tested by transmission electron microscopy(TEM)and average size of microspheres is 150nm.Optical microscope and dynamic light scattering(DLS)show that the size of microspheres increases to 673nm as time extending when they are placed into water environment and temperature is set to 40 ?.The result of thermogravimetric analysis(TGA)shows that there is best performance in higher temperature resistance for core-shell microsph-eres than general microspheres and temperature of the loss of mass is 360 ? and 350 ?,respectively.The experiment of stratigraphic gap simulated by a capillary and the relation between microspheres and nucle-pore membrane show that microspheres deform in a capillary and microspheres perform best in plugging when the size of nucle-pore membrane is 10?m and 12?m,respectively.The property of profile control and water plugging of microspheres is studied.The result shows that these core-shell microspheres achieved best performance in plugging when the permeability of sand packed tube is 0.92D.Meanwhile,plugging ratio,resistance factor and the flow residual resistance are 98.7%,72.5,73.0,respectively. |
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