Preparation And Characterization Of Microcapsule Composites With Stimuli-responsive Release

The stimuli-responsive microcapsule composite material can realize the controlled release of the core material by changing the physical or chemical properties of the shell material under the changes of external influence factors.It has broad application prospects in drug delivery,biosensors,corrosion inhibitors,gel breakers,plugging agents and self-repair materials.In this paper,ammonium persulfate(or azobisisobutyronitrile)initiator is used as the core material,and polyaniline(or polypyrrole)with high density and high storage stability is used as the shell material.Materials such as silica nanoparticles,montmorillonite,petroleum resin or coumarone resin are shell material dopants,and a series of touch release microstructures have been prepared by in-situ polymerization,solvent-free,emulsification-polymerization and other methods.Capsule composite(The microcapsule can be used as the initiator of oil well plugging material).Using scanning electron microscope,transmission electron microscope,energy spectrometer,Fourier transform infrared absorption spectroscopy,X-ray diffraction and thermogravimetric analysis,the morphology,size,shell thickness,shell composition and crystal structure of microcapsules and thermal stability are analyzed.The result shows: 1)With ammonium persulfate as the core material,the microcapsules with polyaniline doped with silica nanoparticles as the shell material are irregular in shape,the particle size is about 5?6 ?m,shell thickness 150?300 nm,the incorporation of silica nanoparticles effectively improves the thermal stability of the microcapsules;2)With ammonium persulfate as the core material,the microcapsules of polypyrrole doped with montmorillonite as the shell material are irregular in shape,particle size is about 8?10 ?m.The surface of the microcapsules is enriched with a large amount of montmorillonite with a rod-like structure,and the incorporation of montmorillonite can effectively improve the suspension and dispersion performance of the microcapsules;3)Use ammonium persulfate as the core material,the microcapsules of petroleum resin doped polypyrrole as shell material are spherical in shape.Particle size is 4?5 ?m,thickness of the shell is about 300?500 nm,polypyrrole shell material that has been soaked in organic solvent and removed the petroleum resin presents an obvious porous structure,the hole diameter is150?200 nm;4)Using azobisisobutyronitrile as the core material,polyaniline doped with coumarone resin with a shell material is a spherical microcapsule,particle size is 10?15 ?m,among them,the microcapsules prepared with Span 80 and Tween 80 composite emulsifiers have better dispersion properties.The release performance of the microcapsules was systematically tested by means of conductivity meter,ultraviolet spectrophotometer,etc.The result shows: by doping other component materials in polyaniline(or polypyrrole)shell material,can successfully realize the microcapsule stimuli-responsive release and its release time can be adjusted by adjusting the type of dopants in the shell material,the amount of doping,the concentration of lye,and the temperature.