| Three-dimensional graphene,as a new type of porous carbon nanomaterials constructed on macroscale,inherits and continues the excellent mechanical,electrical,optical,thermal and chemical properties of graphene in many aspects.At the same time,three-dimensional graphene has abundant pore structure,ultra-light density,low thermal conductivity,large specific surface area,stable network structure and excellent mechanical compressibility,which make it have broad application prospects in the fields of flexible electronic devices,energy storage equipments,intelligent sensing,protection engineering and functional materials.However,the conventional three-dimensional graphene preparation methods represented by hydrothermal method have the problems of insufficient controllability,weak macrostructure designability and difficult in large-scale preparation,which greatly limit the wide use of graphene’s excellent properties.The 3D printing method based on the principle of "additive manufacturing" has the advantages of rapid prototyping,codeable design and assembly,structure precise cutting.It provides a new way for multi-scale structural design and intelligent manufacturing of three-dimensional graphene materials,which makes materials achieve more outstanding optimization in mechanical,electrical and thermal properties.Therefore,in this thesis,the key methods of 3D printing for multi-scale structured preparation of three-dimensional graphene and performance regulation and optimization were studied to realize the structure-function combining design and controllable construction of two-dimensional graphene sheets on multi-scale.The method of regulating and optimizing the mechanical-electric sensing and thermoelectric sensing of three-dimensional graphene by multi-scale structured control parameters was purposed,which provides scientific basis and technical support for the study of controllable preparation and sensing performance of 3D printing graphene macro-materials.The specific contents of this study are as follows:Firstly,the rheological properties of graphene oxide(GO)were regulated by the cross-linking mechanism of ethylenediamine,and the characteristic parameters of printable "ink" were obtained.The 3D printing technology was proposed to realize the controllable construction of graphene materials on macroscale.At the same time,the controllable optimization of 3D graphene performance were realized by adjusting the preparation process parameters.The experimental results showed that the three-dimensional graphene prepared by this method had excellent elastic properties(90% compressive strain could restore 88%)and significant enhancement in mechanical properties,and realized the controllable change of conductivity based on regulating the hydrothermal parameters.Secondly,combining the "bottom-up" fabrication technology with 3D printing technology,3D printing graphene-based sensor was fabricated by in-situ packaging.The mechanical-electric sensing performance of the device was optimized by the design of the pre-constructed three-dimensional graphene structure configuration and unit density.The experimental results showed that the sensor had a wide applicable strain range(the tensile strain sensing response interval was 5%-21%,the compressive strain sensing response interval was 5%-50%)and stable and sensitive mechanical-electric response performance.At the same time,the device had good mechanical-electric sensing response to bending deformation,which was beneficial to its application in wearable flexible electronic sensor to monitor human joint motion.In addition,based on the principle of fractal theory,a mechanical-electric sensing signal recognition method corresponding to the different structure configuration of sensor was proposed,which provided parameters basis for distributed and multi-point sensor monitoring applications.Finally,based on the good conductivity,high carrier mobility and thermo-electric characteristics,the thermoelectric sensing performance of 3D printing graphene-based devices was studied.The experimental results showed that the device had stable heat transfer characteristics and thermoelectric sensing performance under complex conditions,while showing good real-time response and high sensitivity.In addition,the application feasibility of the thermoelectric sensor device in flow field characteristic parameters and wearable human body sensing test were studied through the temperature difference effect produced by the convection induced by wind field.Furthermore,the thermoelectric sensing performance of three-dimensional graphene were effectively regulated by using 3D printing technology. |
