| In recent years, the design and synthesis of organic-inorganic hybridmaterials is a hotspot in materials science. Combining the properties of organicand inorganic components, this kind of hybrid materials has excellent and specialcapability as compared to its components. The hybrid materials can showsynergistic effects of its components effectively by adjusting the proportion of itscomponents, for example, the thermal stability, mechanical intensity and opticalproperties of polymer can be improved by adding of the inorganic componentsand the elasticity and film-formation-ability of the inorganic materials can beimproved by adding of the organic components, thus the novel hybrid materialswith the whole properties of its organic and inorganic components can be obtained.The inorganic/polymer core-shell hybrid materials have novel capability whichwas endowed by the multifarious shell, so such materials have been widely usedin chemistry-surface-modify, catalysis, optics and magnetics.Hybrid nanoparticles have been synthesized by miniemulsionpolymerization in this article. Miniemulsion polymerization is a novelpolymerization method, the size and component of the oil drops don't changeduring the course of polymerization, the oil drops can be seen as minireactors andsuch sub-microdrops become the site of inducement and nucleation by usingco-surfactant and miniemulsion.Titanium dioxide is one of the most practical materials employed in manydomain, not only, due to its outstanding electronic properties, one of the mostphotoactive catalysts, but also because of its high chemical stability andnontoxicity, so we used it as inorganic component in this work. It is well-knownthat it is the anatase polymorph rather than the rutile polymorphs that has thehighest photocatalytic activity. The difficulty in producing an extremely active,phase-pure anatase photocatalyst stems from the fact that rutile is thethermodynamically stable polymorph, and although anatase is kinetically stable, itis readily converted to the rutile phase in the temperature range of 500-800 °C.And it is also too difficult to increase both of its specific surface area andcrystallization in order to improve its photocatalytic activity. In the present work, we report a one-step route by combining theminiemulsion polymerization of polystyrene-co-poly(acrylic acid) (PStA) latexparticles and the coating of titania nanoparticles onto the polymer microspheres.During the process, titania acted as assistant-surfactant was added to enhance thestability of the system because of its charged and hydrophilic properties. Titaniananoparticles were coated on the surface of the polymer by the interactionbetween titania and carboxyl groups. The factors such as TiO2,acrylic acid andhydrophobic agent which influence the morphology and formation of the hybridmaterial are discussed, and the as-prepared hybrid material were characterized byTEM and IR. SEM photographs shows that the sample presented microporus morphologywith a 50 nm aperture. The research results of XRD indicate that the transitiontemperature from anatase to rutile was increased by hybridization with polymersand the crystallite sizes of samples became smaller than pure TiO2 at the sametemperature. TG and XPS results slowed that the sample left a lot of graphitizedcarbon in the remainder, which improved the thermal stability of the hybridmaterials. SPS results present that the band-gap of hybrid microspheres is largerthan that of pure TiO2. In the experiment of photocatalytic degradation of methylorange, the photocatalytic degradation rate of TiO2 hybrid microspheres is 15%faster than that of pure TiO2 prepared by our group, demonstrating that hybridmicrospheres are superior to pure TiO2 in photocatalytic activity.We can endow the hydrophilic groups onto the polymer's surface to makepolymer be coated with TiO2 by copolymer or by changing the hydrophilic/hydrophobic properties of the nanoparticles so as to lead hydrophilic ZnO,NiOinto polymer matrixs with miniemulsion polymerization. Hydrophilic ZnO nanoparticles with –OH or –COOH groups on their surfacewere synthesized in this work, and were modified with monomer MPS (modifiedwith monomer AN if there are –COOH groups on their surface), so as to changehydrophilic ZnO nanoparticles into hydrophobic ZnO nanoparticles and makethem transfer from water phase to oil phase to obtained ZnO coated with polymerhybrid materials. The –OH groups on the surface of NiO nanoparticles were decreased afterthermal treatment at 300℃. When NiO nanoparticles were modified withmonomer MPS(SOCl2 or diethyl amine), the polarity of NiO-MPS is betweenwater and oil, so NiO coated polymer hybrid materials were obtained aftercopolymerization of MPS with monomer. All this indicate that inorganic/organichybrid materials can be fabricated by using this method. In one word, TiO2/polymer hybrid materials can be synthesized byminiemulsion polymerization, furthermore, after thermal treatment the porousTiO2 materials which have the merit of high thermal stability, broad band-gap,large specific surface area, small particle size and high photocatalytic activity wasobtained. The synthesis of ZnO/polymer and NiO/polymer hybrid materials alsoshowed that miniemulsion polymerization is novel and effective for it cansuccessfully lead the inorganic species into polymer matrix and make the one-potsynthesis of core-shell materials come into reality, thus miniemulsion... |
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