Perparation And Performance Research Of Functional Mateirals Based On Polystyrene Microspheres

For the highly monodispersity, preferably spherical shape, the controllability of particlesize and surface electrical, monodisperse polystyrene (PS) microspheres have a very wideapplication. Especially after the proposing of photonic crystal concept, monodisperse PSmicrospheres have become the key factor of assemble colloidal crystals. This paper is aimingat exploiting monodisperse PS microspheres to development functional materials andexploring their performances.Firstly, the monodisperse PS microspheres and modified PS microspheres were preparedby using soap-free emulsion polymerization. Then, using close-packed colloidal crystals andnon-close-packed colloidal crystals assembled with well monodisperse microspheres astemplates to prepare functional materials: Three-dimensional ordered macroporous TiO2(3DOM TiO2) and Polyacrylamide hydrogel photonic crystals.(1) Taking styrene (St) as raw material and acrylic acid (AA) as the comonomer, differentsizes of PS microspheres and modified PS microspheres were prepared by using soap-freeemulsion polymerization method. The results showed that the dosages of monomer, initiatorand solvent had a certain impact on the particle size, monodispersity and emulsionconcentration. Microspheres have a good monodispersity when the amount of AA is less than15%of the total amount of St. Thermal properties of modified PS microspheres is higher thanPS microspheres.(2) The close-packed colloidal crystals were prepared by evaporation self-assemblemethod with modified PS microspheres. Regarding colloidal crystals with orderlyarrangement as template,3DOM TiO2were prepared by sol-gel technology, and then carriedout a preliminary study on the performance of3DOM TiO2.As the temperature was60℃, the morphology of colloid crystals is preferably when themonodispersity was good and the solid content of the emulsion was between4%and5%. Thecolloidal crystals have bright Bragg diffraction light. The Bragg diffraction spectra dispalysingle peaks and their maximum diffraction wavelengths are linear with the diameter of themicrospheres.The visible light colors corresponding to the diffraction wavelengths are agreewith the colors of the colloidal crystals, and illustrate the highly ordered arrangement of thecolloidal crystals.3DOM TiO2were prepared by capillary force filling method, filtration filling method,“sandwich” filling method and “sandwich-vacuum” filling method. The results showed thatthe morphology of the3DOM TiO2prepared by the former two methods was poor, and theformation of over layer was inevitable. While the sandwich-vacuum filling method have beenproved to be simple and rapid for the fabrication of3DOM TiO2without over layers. This3DOM TiO2has a typical inverse opal structure, its macroporos arrange orderedly withuniform aperture. Macroporos form a face-centered cubic structure and connect with eachother. Compared with the reported shrinkage (33%), the shrinkage is smaller (only14%)significantly. Its specific surface area is87.7m2/g, which is larger than the reported57m2/g.The analysis of XRD indicates that the crystalline of3DOM TiO2calcined at500℃is anatase crystal. At the same time, the3DOM TiO2has some photocatalytic activity.(3) With the self-assembly of monodisperse modified PS microspheres, anon-close-packed of colloidal crystals arrays (CCA) was formed under low ion concentration,and then successfully fixed in the polyacrylamide hydrogel with photopolymerization. Thethickness of hydrogel photonic crystals (PCCA) film is1mm and its area is2cm×2cm. Theresults manifested that particle sizes, concentration of CCA, monomer concentration andcrosslinking density had some impacts on the Bragg diffraction light of the gel films.Increasing the concentration of CCA or crosslinking density, the Bragg diffraction peak hadblueshifted. With the increase of particle size or monomer concentration, the Bragg diffractionpeaks had redshifted.The response of polyacrylamide gel photonic crystals to ethanol had been finished. Theresults showed that, as the concentration of ethanol increase, the Bragg diffraction peaks hadblueshifted. The degree of displacement is linear with the concentration of ethanol, every10%change of ethanol concentration, the Bragg diffraction peak shift with an average value is24nm.The polyacrylamide hydrogel photonic crystals have some response to pH afterhydrolyzed. With the increase of pH, Bragg diffraction peaks have redshifted when the pHvalue is between2.36and8.15. However, The Bragg diffraction peaks have blueshifted whenthe pH value is greater than9.6.The hydrogel photonic crystals film has good dehydration-rehydration and reuseperformance. After completely drying at50℃, it regains bright Bragg diffraction light within30minutes by adding water, and still displays a complete Bragg diffraction light after sixtimes of recycle use. The hydrogel photonic crystals film can be preserved in completely drycondition and has a good recycling performance.