| Photonic crystals have a wide range of research and applications in the fields of display and sensing due to their unique structure and optical properties.The preparation of photonic crystals based on the assembly of magnetic colloidal particles induced by an external magnetic field is a rapid technique for the preparation of photonic crystals that has been developed only recently.Compared with the traditional method of preparing responsive photonic crystals using colloidal self-assembly technology,the magnetic response-induced assembly technology has received much attention because of its simple preparation process,high saturation strength,easy magnetization,instantaneous reversible process and easy regulation,etc.Therefore,based on the flexible carrier polymer gel material and magnetic-induced assembly technology,a one-step instantaneous assembly can be realized to prepare gel-based composite colloidal crystal materials,which The brilliant structural color of photonic crystals is permanently preserved.The combination of photonic crystals and gels enables the expression and visualization of information transmission through the structural color change of photonic crystals when the gel matrix is stimulated externally,giving the gel photonic crystal materials value for applications in display and sensing fields,and extending the service life of photonic crystal materials.Based on this,this paper takes magnetically responsive colloidal photonic crystals of ferric tetroxide as a starting point to embed photonic crystals into the gel system,aiming to realize the morphological control and functional integration of photonic crystal hydrogels,in order to broaden the applications of gels in the fields of sensing and display.The main research contents are as follows:(1)The synthesis process of magnetic colloidal nanoparticles with tunable particle size was explored by high-temperature hydrolysis,the synthesis process of silica coating of magnetic colloidal nanoparticles was explored by Stober synthesis,and the mechanism of assembly of magnetically responsive colloidal nanoparticles into one-dimensional chain-like structures under magnetic fields was investigated.Magnetic colloidal nanoparticles with uniform size in the range of 90-180 nm were synthesized by high-temperature hydrolysis using trisodium citrate as the electrostatic stabilizer,ferric chloride hexahydrate as the iron source,anhydrous sodium acetate as the base source,and ethylene glycol as the solvent.The structure,size and other physicochemical properties of the synthesized colloidal nanoparticles were analyzed by SEM,TEM,XRD and FT-IR,which indicated that the synthesized magnetic colloidal nanoparticles had a distinct core-shell structure.The magnetically induced assembly behavior and diffraction pattern of one-dimensional photonic crystals were investigated,and the effects of the size and magnetic field strength of magnetic nanoparticles on the diffraction pattern of one-dimensional photonic crystals were studied.(2)Organogels were selected as substrates loaded with magnetically responsive photonic crystals for visual information sensing.The influence of organic solvents on the synthesis process was investigated.Acrylamide and l-vinyl-2-pyrrolidone were selected as the monomers of hydrogels,glycerol was used as the solvent,and Fe3O4@SiO2 colloidal nanoparticles provided the structural color,and the structurally colored organogels were successfully produced after thermal initiation.The microstructure and antifreeze properties,self-healing properties and mechanical properties of the photonic crystal organogels were analyzed and investigated,and their response behaviors to mechanical forces were studied.The structural color self-healing organogels were prepared by combining magnetic assembly and thermal initiation polymerization,and the influence of solvent on the anti-freezing and self-healing properties of the gels was investigated.The morphology was observed by SEM after freeze-drying;the individual components of the organogels were analyzed by FT-IR spectroscopy;the anti-freezing properties of the gels were analyzed by differential thermal scanning calorimetry to explore the synthesis,anti-freezing and self-healing mechanisms of the organogels,which were synthesized with good self-healing properties and excellent antifreezing properties.(3)Ionic gels were selected as carriers to load magnetically responsive photonic crystals for visualization-conductivity dual sensing,and the preparation process of photonic crystalbased ionic gels was investigated.The ionic gels were formed by photoinitiated polymerization using 1-ethyl-3-methylimidazole ethyl sulfate as the solvent,Ocarboxymethyl chitosan to enhance the self-healing properties,acrylamide and 1-vinyl-2pyrrolidone as the monomers of the hydrogel,and Fe3O4@SiO2 colloidal nanoparticles to provide the structural color.The microstructure of the photonic crystal-based ionic gels and their response to mechanical forces were analytically investigated.The electrical conductivity and sensing properties of the structured color self-healing ionic gels were investigated,which have good signal stability when subjected to deformation and show a significant response to color.The self-healing properties of the ionic gels were investigated,and the synthesized ionic gels have good self-healing properties. |
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