Preparation And Application Of P (Eu ^{3 +} --co - MMA) Functional Microspheres

Monodisperse polymer microspheres with the advantages of uniform size, specific surface area and strong reaction performance are widely used in coating, separation materials and other fields, in which the fluorescent polymer microspheres have become an important part. The traditional fluorescent substances are mainly organic dyes and fluorescent quantum dots, and they often have the shortcomings of short fluorescence lifetime and easy to be disturbed. Recently, rare earth materials with special fluorescence properties have attracted more attention. Because of the longer fluorescence lifetime and narrow emission spectrum, the detection sensitivity is greatly improved. After successfully preparing the colloidal crystals, the functional microspheres are ordered assembly which becomes the development direction of the polymer fields. That is to say, the functional colloidal crystals are obtained by the functionalized of the microspheres. In this paper, we have prepared monodisperse polymer microspheres with narrow distribution, fluorescent microspheres and functional colloidal crystals. The contents are carried out mainly as follows:Firstly, preparation of monodisperse poly-methyl-methacrylate microspheresThe monodisperse non crosslinking/crosslinked poly-methyl-methacrylate microspheres have been synthesized with methyl methacrylate (MMA) as monomers, potassium sulfate (KPS) as initiator, methacrylic acid (MAA) as stabilizer, divinylbenzene (DVB) as cross-linking agent. The composition, morphology and polymerization mechanism of the poly-methyl-methacrylate microspheres are characterized by fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and powder X-ray diffraction (XRD). The results show that we could get poly-methyl-methacrylate microspheres with consistent particle size which located between 200nm to 400nm based on the boiling system. and the same time we can find no obvious aggregation. The reaction system are studied with different time, the soap-free emulsion polymerization reaction mechanism "Aggregation-Microcapsule-Dissociation" is put forward, which is different from the classical emulsion polymerization mechanism and meanwhile is in line with the theory of the reaction kinetics. At the same time, the reaction conditions of the polymer microspheres are studied, which make the particle size of the poly-methyl-methacrylate microspheres could be controlled.Secondly, preparation of Eu3+-co-PMMA copolymer microspheresThe fluorescent polymer microspheres have been prepared with methyl methacrylate (MMA) as monomers, potassium sulfate (KPS) as initiator, methacrylic acid (MAA) as stabilizer, sodium dodecyl sulfate (SDS) as emulsifier, rare earth (Eu(MAA)3phen) as fluorescent substance. By the means of fourier transform infrared spectroscopy (FT-1R), simultaneous thermal analysis (STA), coupled with inductively coupled plasma mass spectrometry (ICP-MS), it is indirectly proved that the methyl methacrylate (MMA) and the rare earth three element complex (Eu(MAA)3phen) is combination with copolymerization key (a form of covalent bond). The results of scanning electron microscopy (SEM), X-ray diffraction (XRD) indicate that Eu3+-co-PMMA fluorescent copolymer microspheres are amorphous structure with a clean surface which are in a good spherical shape and uniform particle sizes. Through the spectral analysis of ultraviolet spectrum, fluorescence spectrum and inverted fluorescence microscope, the Eu3+-co-PMMA copolymer microspheres present the characteristic fluorescence of rare earth, and the flourescent intensity enhances with the increase content of rare earth complexes, without the occurrence of the concentration quenching phenomenon.Lastly, preparation of colloidal crystal beadsBased on the monodisperse polymer microspheres, the long-range-ordering colloidal crystal structures are builded by the microfluidic method. The structure colour and microstructure of the colloidal crystal beads are analyzed through scanning electron microscopy,3D laser scanning confocal microscope and polarizing microscope, the observations show that the bead is in a good spherical shape, nanoparticles in the bead is arranged hexagonally and such ordering extends from the bead surface to the center. The analysis of particles sizes of colloidal crystals, the beads appeare in good dispersion by the microfluidic technique, and the range of the colloidal crystal beads are wider. The reflection wavelength of different structure colour colloidal crystal beads are measured by the optical microscope together with optical fiber spectrometer which meets the requirements of the standard color chart. The inverted fluorescence microscope indicates that the functional colloidal crystal microspheres show little difference between the rare earth fluorescent properties which roots in the special structure and it could be longer stayed. In order to improve the mechanical stability of the colloidal crystal beads, we heat treated them with different temperature. The ultrasonic cleaning instrument and nanoidentation confirm that with the increase of the treatment temperature, the mechanical properties of the collidal crystal beads improve, which provids basic research for the potential applications.