Preparation Of Two-Dimensional Molybdenum Disulfide And Its Modification To Thermal Stability And Tensile Properties Of Polycarbonate

Recently,the unique physical properties of two-dimensional inorganic layered materials due to quantum size effects（related to nano-scale thickness）have received great attention.Among them,molybdenum disulfide（MoS₂）,as a member of the two-dimensional inorganic layered material,is a unique sandwich sandwich structure with a wide band gap structure,high carrier mobility and switching ratio.It is widely used in many fields such as photocatalysis,composite preparation and pollutant degradation,especially in optoelectronic devices.In addition,the nano-sheet structure of the two-dimensional MoS₂ imparts a high specific surface area,making it easy to adsorb the polymer and enhancing the interaction with the polymer chain,so the two-dimensional MoS₂ is an excellent reinforcing agent for the polymer material.However,like graphene,many of the superior properties of MoS₂ must be stripped into a layered material to reach its potential.At the same time,the surface of MoS₂can be functionally modified to retain a variety of excellent properties and used in sophisticated methods to achieve composites with improved properties.Therefore,there is a need to find a simple stripping method to produce a large number of single-layer or multi-layer MoS₂ nanosheets for obtaining two-dimensional MoS₂/polymer nanocomposites with excellent properties.In this paper,from the perspective of facilitating the acquisition of polymer nanocomposites,the preparation of MoS₂ nanosheets was carried out by four different stripping methods of liquid phase ultrasonic stripping.The results show that the MoS₂nanosheets stripped by hydrazine hydrate pretreatment are more suitable for obtaining highperformance two-dimensional MoS₂/polymer nanocomposites.Secondly,the surface of the MoS₂ nanosheet is modified with organic molecules to improve its dispersibility in the polymer matrix.The thermal stability and tensile properties of the MoS₂/polymer nanocomposites obtained before and after modification of MoS₂ nanosheets were investigated.The specific work of the thesis is as follows:（1）The MoS₂ raw materials were stripped by four different stripping methods of liquid phase ultrasonic stripping,respectively,through UV-Vis,TEM,AFM and X-ray diffraction（XRD）.By comparison and other means of characterization,a stripping route with good stripping effect and high stripping yield was selected to prepare thin-layered MoS₂ nanosheets.It was found that high yield and high quality MoS₂ nanosheets can be obtained by hydrazine hydrazine pretreatment.（2）The MoS₂ nanosheets obtained by the hydrazine hydrazine pretreatment method were selected as the filler and the PC was used as the matrix.The two-dimensional MoS₂/PC nanocomposites were prepared by solution blending.The morphology and structure of the composites were observed and analyzed by means of infrared spectroscopy（FTIR）,scanning electron microscopy（SEM）and XRD.The effects of the addition amount of MoS₂ nanosheets on the thermodynamic properties of two-dimensional MoS₂/PC nanocomposites were investigated by DSC,TG and tensile tests.The results show that the MoS₂ nanosheets are successfully dispersed into the PC matrix,and the thermal stability and tensile properties of the composites are improved due to the addition of MoS₂ nanosheets.When the content of MoS₂ nanosheet filler is 3%,the thermal stability and tensile properties of the composite is most effective.（3）The MoS₂ nanosheets prepared by liquid phase ultrasonic stripping were organically modified,and then the polycarbonate/functionalized molybdenum disulfide（KH570-MoS₂）nanocomposites were prepared by solution blending.The morphology and structure of the modified composites were compared with the unmodified composites by infrared spectroscopy（FTIR）,scanning electron microscopy（SEM）,XRD and other characterization methods.The modified MoS₂ nanosheets were found in PC matrix.The dispersion in the composite is more uniform,and the thermal stability and tensile properties of the composite material are more significantly improved.