Fabrication Of Structural Color Materials With High Structural Stability And Their Applications

Three-demensional ordered photonic crystals(3D-PCs)and the inverse opal are the typical representative of the structural color materials,the unique optical properties of the 3D-PCs were produed by the modulation of light from periodic nanostructures with a feature size on the scale of the wavelength of visible light.But weak mechanical stability,which was resulted in the point-to-point contact of the nanospheres or the weak intermolecular forces of the filling materials,have been considered as major obstacles for actual applications of 3D-PCs in the field of display,sensors,fabrics printing,anti-counterfeiting and so on.In this thesis,the adhesive,polyacrylate(PA),was designed and synthesized,and the co-assembly of PS and PA were realized and the opal structural color materials with high structural stability were obtained.A new fabric printing method was developed utilizing the PA adhesive system,and multicolor output on fabrics were realized.The robust polymer inverse opal structural color films with fabricated through the template method,and the films exhibited excellent anti-counterfeiting properties.Monodispersed polystyrene(PS)nanospheres with different sizes(177 nm-292 nm)were synthesized by emulsifier-free emulsion polymerization,and silicon dioxide(SiO2)nanospheres with different diameters(240 nm-380 nm)were prepared under a modified Stober method.The PDI of the two kinds of nanoparticle samples were all less than 0.025 which demonstrated that the monodispersity of PS and SiO2 nanospheres.The adhesives,polyacrylate(PA)and fluorinated polyacrylate(FPA)polymer latex,were synthesized.The co-assembly of PS and PA was realized by thermal-assisted process on the glass substrate,so the PS structural color materials with photonic crystal structure and amorphous arrays were locked by PA due to the good cohesiveness,hardness and modulus were enhanced up to 1.15 GPa and 2.13 GPa,and the structural color films with stable colors and good mechanical stability were prepared.Because of the different surface energy of the PA and FPA,the surface wettability of the structural color films could be changed by doping different adhesive in the self-assembly process(contact angle 25° to 140°).A simple two-phase self-assembly method was developed for printing the fabrics,the voile polyester fabric was covered over the surface of the mixture,then PS and PA were assembled on the voile fabric driven by the capillary force,and the structural color was transferred to the fabrics.Utilizing the periodic array locking effect of PA polymers,the nanosphere arrays were adhered to the fibers tightly,and the structural stability of the printed fabrics was enhanced dramatically.With the assistance of the multiple-fluted template,the patterning process and multiple structural color output were simultaneously achieved by using the method.In addition,the environmentally friendly colloidal crystals are potential substitutes for organic dyes and pigment,and the work also support important evidence for fiber coloration.Similar to the optical properties of the opal structure,the inverse opal also possessed the ability to control the output of the structural colors.Because of the poor mechanical strength and toughness of the traditional organic and inorganic materials,the problems of the structural stability in the inverse opal will limit their applications.Based on the tightly packed chains and the excellent mechanical stability of polyvinylidene fluoride(PVDF)resin,the free-standing PVDF structural color films with ordered or amorphous arrays were prepared through the template method.The patterned PVDF films with order arrays changes between six distinct color states when the viewing angle increases from 5° to 45°,the reflection peaks blue-shifted 130 nm-150 nmwhich makes the plastic films a higher anti-counterfeiting material.The PVDF film exhibited good flexibility,and the tensile(37.9 MPa)and compressive tests(13.8 MPa)demonstrated its excellent durability.Another kind of PVDF films which possess a bilayer inverse heterostructure(BLIHS)which contains ordered and amorphous arrays were successfully prepared.Based on the selectively reflect or scatter the visible light through the novel photonic structure,the switch between hiding and displaying patterns could be easily realized by changing the viewing angles.And the as-prepared films exhibited inherent excellent mechanical strength(29.7 MPa).