Preparation Of Core-shell Polymer/CdS Fluorescent Composite Microspheres Via Pickering Emulsion Polymerization

Recently, organic-inorganic composite materials have attracted extensiveattention. These composite materials have been widely used in optical, electrical,magnetic, catalytic, sensors, medicine and biology fields, which have both theadvantages of organic and inorganic materials. Because the traditionalpolymerization technology are generally used to prepare composite materials withinorganic materials as core and polymer as shell. In this paper, Pickering emulsionpolymerization was employed to prepare core-shell structural composite materialswith polymer as core and inorganic materials as shell, using solid particles asemulsifier. These prepared core-shell composite materials were characterized byScanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transforminfrared spectroscopy (FTIR), Photoluminescence spectra (PL), Differentialscanning calorimetry (DSC) and Thermo gravimetric analysis (TG). The mainresearch contents are as follows.1. Cadmium sulphide nanocrystal (CdS) was prepared by hydrothermal method,Liquid-Solid-Solution (LSS) method and the aqueous phase synthesis, respectively.Their chemical structure and fluorescence properties were characterized andanalyzed. The emulsifying effect of toluene emulsion is investigated, which areemulsified by CdS nanocrystal, using toluene for the organic phase. The resultsshow that the water-soluble CdS nanocrystal have the best emulsifying effect andbe able to form stable oil in water (O/W) type emulsion, which are prepared by theaqueous phase synthesis.2. Stable O/W emulsion was prepared by using styrene (St) monomer dissolvedoil-soluble initiator for the dispersed phase and CdS nanocrystal was used asemulsifier. The CdS/PS composite microspheres were prepared by polymerization.The composite microspheres were characterized by SEM, XRD, FTIR, PL and DSC.The results show that the composite microspheres have the core-shell structure withPS as core and CdS nanocrystal as shell. The composite microspheres have goodfluorescence properties, whose glass transition temperature was elevated by5centigrade. 3. The CdS/PMMA composite materials were prepared by Pickeringpolymerization, using methyl methacrylte (MMA) monomer for the dispersed phaseand CdS nanocrystal as emulsifier. The composite materials are characterized bySEM, XRD, FTIR, PL and TG. The results show that the composite microsphereshave the core-shell structure with PMMA as core and CdS nanocrystal as shell. Thecomposite microspheres have better fluorescence properties, whose thermalstability has been elevated.4. Butyl methacrylate was emulsified in water with CdS nanocrystal asemulsifier and2,2azobis (isobutyronitrile)(AIBN) was used as initiator. TheCdS/PBMA composite materials were prepared by radical polymerization. Thecomposite materials are characterized by SEM, XRD, FTIR, PL and TG. The resultsshow that the composite microspheres have better fluorescence properties andthermal stability.