Facile Methods For The Preparation Of Monodispersed Au/PS,Pd/PS Composite Microspheres, And Hollow Silica Micro-spheres And Investigation On Their Properties

In recent years, composite microspheres have attracted much attention, especiallythe preparation and application of the inorganic–organic composite particles. It is still oneof the fastest growing areas of materials research due to the combination of theadvantages of all the components. Inorganic–organic composite particles can offer a widerange of applications such as catalysis, optical, electrical and biomaterials.1. In this work, the Au/PS composite microspheres could be prepared successfullythrough the reduction of （AuCl₄）-, which were previously attracted to polystyreneparticles. First,（AuCl₄）-coordinated with allylthiourea （AT） at first stage, this wayensured the successful preparation of the composite particles. The polystyrene particleswith （AuCl₄）-ions on the surfaces were prepared via surfactant emulsion polymerization.Allyl thiourea was used as an efficient functional co-monomer which enables the （AuCl₄）-ions attract to polymer particles through coordination. Then by adding reducing agent,sodium borohydride （NaBH₄） at room temperature,（AuCl₄）-ions were reduced tozero-valent gold to form the Au/PS composite microspheres. Meanwhile, the effect of theamount of HAuCl₄、NaBH₄、AIBAwas discussed to theAu/PS composite microspheres.TEM, SEM and XPS characterizations confirmed the formation of Au/PS compositemicrospheres. The resulted composite microspheres have efficient catalytic activity forthe degradation of MB, the degradation of MB reached96.4%in the presence of Au/PSafter10min. Also SERS signals could be detected even under the low concentration of1×10^-7mol/L of rhodamine6G （R6G）.2. The Pd/PS composite microspheres were prepared successfully by dispersionpolymerization process and the as-prepared PS particles were negatively charged due tothe functional co-monomer, methacrylic acid. In this method, PVP acted as bothdispersant and reducing agent, so no additional reducing agents were needed. Thereduction of Pd²⁺ions, which have been attracted onto the negatively charged surfaces ofPS particles. The formed Pd particles were attached onto the functionalized PS particlesto ensure Pd/PS composite microspheres can be obtained successfully. Meanwhile, theeffect of the amount of MAA、AIBN、PVP、PdCl₂was discussed to thePd/PS compositemicrospheres. TEM, SEM and XPS confirmed the formation of Pd/PS compositemicrospheres. The resulted composite microspheres have efficient catalytic properties forSuzuki reaction. The yield of the biphenyl was95.5%.The catalyst could be easily separated from the reaction mixture just by filter and can be reused without notable lossof catalytic activity.3. Mono-dispersed hollow-microsphere chemosensors have been preparedsuccessfully. TEM characterization confirmed the silica hollow microspheres withuniform diameter size （180-640nm）, controllable thickness （10-27nm） were performedthrough changed different conditions. The hollow-microsphere chemosensors exhibitedoutstanding efficiency for detection, adsorption and removal of Hg²⁺in solution. Theadsorption capacity could reach32.3mg/g and the color of solution changed instantly. Inaddition, the sensor1had can be used in a wide pH range from3to8, and has highselectivity for detecting Hg²⁺ions over other heavy metal ions. In addition, forcomparison with the sensors grafted onto SiO₂/PS composite spheres, it could be seenclearly that the superiority of using hollow silica spheres as a carrier was promising forchemosensor to detection, adsorption and removal of heavy metal ions in solutions.