Colloid-assisted Fabrication Of Two-dimensional And Three-dimensional Ordered Micro-structures And Their Applications

Colloidal crystals are that people use colloidal materials to simulate ideal photoniccrystals in nature. Currently, they are divided into one-dimensional, two-dimensionaland three-dimensional photonic crystals. Pattern structure with special functions alsoattracted increasing attention, and colloidal lithography afford an important means toprepare special surface patterns. In this paper, we use reliable technology to fabricateassembled three-dimensional, two-dimensional colloidal crystals. Based on thethree-dimensional colloidal crystals, the inverse opal photonic crystals/macroporousmaterials were prepared. Based on colloidal lithography, micro and nano patternedsurfaces were obtained. By optimizing the structure and chemical modification, thefunctional and intelligent patterned surfaces were achieved.(1) Using three-dimensional colloidal crystal as the template, we prepared a highdegree of order titania inverse opal structure, and the macroporous materials remainsintac, possess anatase crystal form, as well as spectral band gap. They have potentialapplication in the optical, catalytic sensing and other fields. First, we synthesizedthree polymeric microspheres (PMMA microspheres, P (St-MMA-AA) microspheres,PS microspheres) as building block, and the three-dimensional colloidal crystalsubstrate was prepared by a single-or dual-substrate deposition. The preparedThree-dimensional crystals possessed perfect degree of order, and narrow FWHM ofbandgap. Further, we use two types of the precursor solution to pour into the colloidalcrystal, after baking process, the inverse opal titania macroporous material wereobtained. One precursor is the mixture of isopropanol tin and tetrabutyl titanate, the other is only tetrabutyl titanate. We found that the three-dimensional macroporousanatase titanium dioxide in the preparation of a small amount of tin doped can beprepared at500℃, and remained relatively intact structure. Without tin-doped, onlymacroporous rutile titanium dioxide samples were obtained at500℃. Although itcan be converted into anatase at high temperature, the structure would be completelycollapsed at that high temperature. Because there are multiple nuclei tin crystals, theporosity is large. This further increases the porosity of the macroporous materials,which can reach over90%, much higher than the theoretical value.(2) We use two-dimensional colloidal crystal structure as a template to preparepolymer nanosctructure, and further expand its applications in antireflection, SERSsubstrate and enhanced cell adhesion. First, we use the method of air-water interfaceassembly to prepare a layer of PS microspheres on a single-layer PET. Using PS2Dcolloidal crystals as the template, the reactive ion etching (RIE) was adopted toprepare the nanostructures. In the RIE process, the PS spheres became graduallysmaller, while the frustum structure appeared on the bare PET wafer. As the etchingtime increases, the template gradually disappeared, frustum-shaped structure into thevertebral structure. By regulating the size of the spheres, the nanostructure withdifferent period can be obtained on the PET. Secondly, by tuning the chemicalcomposition on the surface, the superhydrophobic surface can be obtained. The staticcontact angle reached to approximately150°. The prepared structure possessedanti-reflection property, which can be proved from the transmission and reflectancespectra. Further, we modified graphene oxide on the two-dimensional nanostructure.The prepared surface exhibited enhanced adhesion effect for different types of cells.On the other hand, we deposited gold films on the two-dimensional nanostructure tofabricate the SERS enhanced substrate, and it show outstanding property of thedetection of trace molecules.(3) Using small gold particles as templates, the silicon nano-pillar arrays with smallsizes were prepared, which possess good antireflection effect in the deep UV region;furthermore, the prepared structure had good superhydrophobic property. First, weassemble the gold nanoparticles monolayer by the interfacial method. Further, we heated the Au monolayer in the tube furnace to form large gold particles arrays. Usingthe gold nanoparticles as a template, the RIE route can fabricate the silicon nano-pillararrays with sub-100nm scale. We further tested antireflection effect for the preparednanostructures in the ultraviolet region and the visible region. It was difficult toachieve such small size nanopillar arrays using traditional methods. Our approach issimple, and can be large-scale production. It is significant to be applied in the deepultraviolet region of optical equipment.