Preparation And Properties Of Molybdenum Disulfide-based Nanocomposites

As representative of intelligent soft materials,ER fluid itself means that solid particles with polarizing ability are dispersed as a dispersed phase into an insulating medium(such as silicone oil,mineral oil)as a continuous phase to form a stable suspension system.Under the control of an external electric field,the rheological properties of the suspension system assembly will change significantly.The solid particles dispersed in the ER suspension will polarize and form a chain structure along the field direction by the applied electric field.Therefore,they exhibit a phase change from a liquid to a solid.In this fast and reversible process,the rheological properties of the ER fluid have a significant change.In recent years,the emerging two-dimensional layered materials have been used as electrorheological materials many times.Among these two-dimensional materials,molybdenum disulfide has a low density and controlled conductivity due to its two-dimensional layered structure similar to graphene,Corrosion and heat resistance,large specific surface area and many other advantages have made it the focus of attention in the field of electrorheology.Molybdenum disulfide has been widely used in electrorheological fluids,and its particle morphology and size have a very important influence on its electrorheological effect.At the same time,because the polarization ability of molybdenum disulfide itself is not strong,the conductivity control is more complicated,which makes it unsuitable for use as an electrorheological material alone.By introducing a material with strong polarization ability as an insulating layer,the molybdenum disulfide is coated to reduce its conductivity Is an effective means.Starting from this,we designed and prepared molybdenum disulfide nanoparticles with special morphology and formed composite materials by doping with polyaniline,titanium dioxide and silicon dioxide.The following are the main contents of the experiment:Prepared by using a simple two-step method,first a flower-like molybdenum disulfide with a multi-level structure was synthesized by hydrothermal method,then the surface of molybdenum disulfide particles was coated with titanium dioxide by hydrolysis method,and then PVP was discussed as the surface.The active agent plays a huge role in the formation of flower-like molybdenum disulfide.At the same time,TiO2 as the outer layer of the core-shell structure is very effective in limiting the excessively high conductivity of the molybdenum disulfide particles and improving the overall polarization ability of the composite material.The particle electrorheological effect is significantly enhanced.(2)The size of the flower-shaped molybdenum disulfide is further reduced by improving the synthesis method,its density is further reduced,and the suspension stability is enhanced,and then the insulating effect is stronger.Silica is used to coat the molybdenum disulfide particles as the conductive core using the Stober method,A new core-shell structure MoS2 @ SiO2 nanocomposite was prepared,with uniform product morphology and size,which greatly enhanced the suspension stability of the electrorheological material as a dispersed phase,and at the same time The conductivity of the material itself is greatly reduced,and the surface roughness makes the polarization ability of the particles further enhanced,making the material more suitable for use in the field of electrorheology.(3)The aniline monomer first forms a fibrous ED precursor with molybdate ions,and then undergoes a polymerization reaction and a hydrothermal reaction to form a MoS2 @ PANI composite material.Then,in order to further reduce the conductivity,pass Stober water on the surface of MoS2 @ PANI The solution method coats a layer of SiO2 to achieve the effect of insulation to obtain the final product MoS2 @ PANI @ SiO2 ternary blended composite material,which greatly enhances the current-changing effect of the material.(4)Combine the tubular titanium dioxide with a small amount of molybdenum disulfide to form a composite material by hydrothermal method and ultrasonic assisted stripping method,and then effectively reduce the electrical conductivity of the tubular TiO2 @ MoS2 composite material by calcination to control it to a certain level It is beneficial to the application of tubular TiO2 @ MoS2 composite materials in the field of electrorheology.The morphology of the materials prepared above was characterized by scanning electron microscope(SEM)and transmission electron microscope(TEM).The structure was characterized by X-ray powder diffraction,transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS),and Raman spectrometer.In addition,the rheological behavior of the electrorheological fluid prepared by the above materials was tested by a rotary rheometer,and its dielectric properties were analyzed by dielectric spectroscopy.