Method for preparing high-expansion nano silica composite microspheres

Abstract

The invention relates to the field of nano silica processing treatment and in particular relates to a method for preparing high-expansion nano silica composite microspheres. The method for preparing high-expansion nano silica composite microspheres comprises the following steps: performing surface grafting modification on SiO2 nanoparticles by using a surface modifier; adding the modified SiO2 nanoparticles into an organic solvent, simultaneously adding a dispersing agent, monomer acrylamide, acrylic acid, a cross-linking agent and an initiator, and ultrasonically and uniformly dispersing; introducing nitrogen into the dispersed solution for bubbling to remove oxygen; carrying out a polymerization reaction after oxygen removal; and repeatedly washing by using ethanol, thereby obtaining the composite microspheres. The microspheres disclosed by the invention have high structural stability, even if the solution temperature is close to the boiling point, the microspheres do not split, and the expansion properties are improved; and moreover, the initial size of the microspheres is less than 1 micron, the microspheres can be applied to plugging of tiny cracks, the final expansion ability can be over 10 times, and the microspheres have good salt tolerance, wide application range and reliable plugging capacity.

Description

technical field [0001] The invention relates to the field of nano silicon dioxide processing, in particular to a method for preparing nano silicon dioxide composite microspheres. Background technique [0002] Nanocomposite microspheres are particles formed by surface coating or compounding of particles of two different particle sizes, such as figure 1 As shown, the mother particle 1 is micron or submicron, and the coated sub-particles 2 are nano-sized particles, which are finally coated into composite particles 3; Functional effect, and can make the surface of a particle produce new physical, chemical, mechanical properties and new functions, and because of the increase in surface area after coating, it can also improve the rate of chemical reaction or the performance of catalyst. [0003] For example, when it is necessary to block underground water seepage, expansion plugging particles and viscosifiers are required. The composition of the groundwater layer is complex, wit...

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Problems solved by technology

[0003] For example, when it is necessary to block underground water seepage, expansion plugging particles and viscosifiers are required. The composition of the groundwater layer is complex, with a certain degree of salinity and salinity, so it is impossible to use a single organic or inorganic plugging medium For plugging, the two need to be combined; in the prior art, clay and organic matter are usually compounded by force. Although this plugging agent maintains good expansibility, the particles are relatively large, generally at the millimeter level. For finer cracks, it cannot be sealed at all, and because the two are combined in a common physical way, the structure is relatively unstable, and may leak again as time goes by. In areas with high salinity groundwater, the sealing capacity will be reduced. significantly decreased

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