Fabrication Of Microspheres With Novel Structure Based On Multiple Pickering Emulsion Templates

Novel microspheres with special structure (e.g. Janus particle、multi-hollow microsphere)have attracted more and more attention due to their outstanding properties and applicationsendowed by their special structure. Based on double Pickering emulsion templates, this studyprepared some novel microspheres by controlling relative factors. The innovative ideas of thisstudy can be concluded as follows: for the first time, multi-hollow magnetic Janus sphereswere successfully fabricated by using double Pickering emulsion method, which caneffectively and simultaneously solve two difficulties, including low output and controllabilityof Janus geometry, which cannot be overcame by other Janus preparation methods. Moresignificantly, our method can conveniently adjust the Janus-balance of the target products.Meanwhile, through changing the component of organic phase, we manufactured a kind ofhierarchical porous microsphere and this microsphere was further applied as supporter forloading catalyst materials to promote the catalytic efficiency and recyclable catalytic ability.The main contents and results of this study are listed as follows:1. Fabrication of multi-hollow magnetic Janus microspheres. Stable double Pickeringemulsions (WF/O/W), in which aqueous Fe3O4dispersion was used as inner water phase (WF),were produced by employing hydrophobic fumed silica (H30) and hydrophilic meso-poroussilica (MSNs) as emulsifiers for inner interface and outer interface, respectively. Wesystematically investigated the influences of Fe3O4nanoparticle concentration, H30content,and volume ratio of WF/O on the double emulsion formation and consequently on thestructure of the resulting Janus microspheres. Optical microscope and scanning electronmicroscope (SEM) were adopted to survey the microspheres prepared under differentconditions. The results show that the target Janus with voids distributed within one side of thesphere can only obtained under proper condition.2. Janus-balance controllability and magnetic induced orientation of the Janusmicrosphere. Anisotropic microsphere with different Janus-balances was manufacturedthrough varying the WF/O volume ratio. To explore the relationship between Janus-balanceand WF/O volume ratio, we deduced the theoretic Janus-balance and calculated theexperimental Janus-balance of the target Janus prepared under different conditions based on maximum packing fraction theory. At the same time, the magnetic anisotropy of theas-prepared Janus microspheres was confirmed by energy dispersive X-ray (EDX) and alsothe magnetic induced orientation property was studied. The results demonstrate that the Janusmicrospheres can be orientated under magnetic field, in which all the Janus spheres wereorientated with multi-hollow part standing at the same side.3. Preparation and application of hierarchical porous microsphere. Based on doublePickering emulsion method, we fabricated hierarchical porous microspheres with variousinner structures by adjusting the component of middle oil phase. The prepared microsphereswere sulfonated by concentrated sulfuric acid and the absorptive ability of the resultingproducts was studied; besides, the sulfonated microspheres were dispersed in [Ag(NH3)2]+solution and in situ reduced by sodium borohydride to obtain Poly(St-DVB)/Agnanocomposite spheres. We examined their catalytic ability and the results appear that theresulting Poly(St-DVB)/Ag nanocomposite spheres have excellent catalytic efficiency andrecyclable catalytic property as well.