Synthesis Of PMMA/Au Microspheres And Au-embedded Complex Porous Silica By Using Amphiphilic Ionic Liquids As Modifying And Templating Agents

In this paper,Au nanoparticles?Au NPs?were anchored on PMMA microspheres by amphiphilic ionic liquids as bridge linker to form PMMA/Au microspheres.Au-embedded complex porous silica materials have been synthesized via using PMMA/Au microspheres and amphiphilic ionic liquids as templates.The were explorated preliminary.The primary exploration was carried out for the study on the adsorptive and catalytic characteristics of the Au-embedded complex porous silica.The content is showed in the following four aspects.Firstly,amphiphilic ionic liquid(1-hexadecyl-3-methylimidazolium chloride(AIL₁₆)was used as modifier to coat the PMMA microspheres after the formation of PMMA microspheres with different sphere diameter.The characterization of SEM and electrophoresis experiments confirms that the PMMA/AIL₁₆ microspheres possess high Zeta potential?+72 m V?in the mass ratio of m(AIL₁₆)/m?PMMA?= 5:1.The results show that the close-packed arrary of AIL₁₆ on the spherical PMMA microspheres?²00 nm?can be formed,that is,the PMMA/AIL₁₆ microspheres with positive charge.Secondly,electronegative citrate-capped Au NPs-Cit.-were prepared by using citrate?Cit.-?as reducing agent and stabilizer,or Na HB4 as reducing agent and Cit.-as stabilizer.Then,the Au NPs-Cit.-were adsorbed on the PMMA/AIL₁₆ microspheres.The tests of TEM found that only a few particles of the Au NPs-Cit.-with 10 nm diameter were adsorbed on one PMMA microsphere.,and the Au NPs-Cit.-with 3.5 nm diameter can be anchored on the PMMA microsphere with relatively dense arrary way to form the complex PMMA/AIL₁₆@?3.5 nm?Au NPs-Cit.-microspheres.It was found that PMMA/AIL₁₆@Au NPs microspheres with Au NPs?2⁷.4 nm?anchored discretely on the PMMA/AIL₁₆ microspheres can be also synthesized through the adsorption of AuCl₄^-on the positive charge PMMA/AIL₁₆ microspheres,and subsequently,in situ reduction.Complex PMMA/Au NPs-AIL₁₆ microspheres with monodisperse Au NPs-AIL₁₆?2 nm?adsorbed on the surface of PMMA microspheres can be prepared by an electrostatic adsorption assembly of the preformed electropositive AIL₁₆-stabilized Au NPs-AIL₁₆ on the unmodified PMMA microspheres.Thirdly,the measurements of small-angle XRD,TEM and nitrogen sorption experiment show that the Au-embedded ordered double porous silica?Au@macropore/SBA-3?was synthesized by a sol-gel process under acidic condition using PMMA/AIL₁₆@Au NPs-Cit.-or PMMA/AIL₁₆@Au NPs microspheres as macroporous template,AIL₁₆ as mesoporous template,and tetraethylorthosilicate?TEOS?as the silica source.The Au-embedded ordered double porous silica possess spherical macropores with Au NPs embedded discretely within the inwall of the macropores,and the wall of the macropores consists of highly long-range ordered hexagonal mesoporous silica?SBA-3 type?channels with average pore size of 2.94 nm and the BET surface area of 912.17 m2/g.The quality of the Au-embedded double porous silica prepared by a sol-gel process under acidic condition is better than that of Au-embedded double porous silica synthesized by hydrothermal process under alkaline condition.Moreover,the tests of small-angle XRD,TEM and nitrogen sorption experiment indicate that the Au-Fe₃O₄-embedded ordered mesoporous silica?Au-Fe₃O₄/MCM-41?with average pore size of 2.5 nm,the BET surface area of 920.54 m2/g,and Au NPs or Fe₃O₄NPs?¹0 nm?dispersed randomly in the highly ordered mesoporous network was synthesized by a hydrothermal synthesis procedure under basic condition using AIL₁₆ as template and TEOS as the silica source in the mixed dispersion of the hydrophilic Au NPs and Fe₃O₄@SDS/AIL₁₆.Fourthly,it was found that the Au-embedded ordered double porous silica?Au@macropore/SBA-3?displays a highly catalytic performance for the catalytic reaction of 4-nitrophenol by using the Au@macropore/SBA-3 as catalyzer.The catalytic products can be obtained within 30 min,while the catalytic products can not be observed without the Au@macropore/SBA-3 within 60 min.At sametime,the properties of two kinds of dyes?methylene blue and Zang Hong T?adsorbed on Au-Fe₃O₄/MCM-41 were also studied.It was found that Au-Fe₃O₄/MCM-41 had strong adsorption properties?the decolorization rate is more than 98% in 5 minutes?and the Au-Fe₃O₄/MCM-41 can be rapidly separated from the solution under external magnetic fields.