Preparation Of Environmentally Sensitive JANUS Particles And Construction Of Self-driven Motors

In recent years,Janus particles with environmental sensitiveness have received extensive attention,because they have the asymmetric characteristics on physical or chemical properties such as a snowman,mushroom Janus particles and surface hydrophilicity-hydrophobicity.There are several preparation methods of Janus particles,among this,Pickering emulsion method has been extensively applied due to several advantages such as easy operation,large production and simple post-process.In this paper,semi-strawberry type SiO2 Janus particles have been prepared using Pickering emulsion method and subsequent amino modification.Then paraffin-water emulsion was stabilized by amino modified SiO2 microspheres with large size.After paraffin cooled down,part of SiO2 microspheres were embedded in paraffin,then the hydrophobicity modification on surface of Si02 microspheres was carried out by amide reaction and eluted using cyclohexane to remove paraffin.SiO2 microspheres with small particle size modified by epoxy and Fe3O4@SiO2 microspheres were self-assembled to obtain semi-strawberry Janus particles under interaction of amino and epoxy group.In the whole modification,SiO2 microspheres,Fe3O4,and Fe3O4@SiO2 were spherical and uniform particle size which could be controlled by amount of ammonia,sodium oleate and TEOS,respectively.Compared with Fe3O4 magnetic saturation intensity,the magnetic saturation intensity of Fe3O4@SiO2 and Janus particles have declined dramatically owing to decrease of Fe3O4 unit quality content and shielding effect of SiO2 layer.The formation of Janus particles should owe to self-assembly between amino and epoxy groups,which was confirmed by XPS results.To construct the self-driven motor,Poly(MAA-co-DVB)@ Pt @ PNIPAM Janus particles with catalysis and thermo-sensitivity have been prepared by combining physical sputtering with chemical polymerization.A novel kind of self-driven motor was fabricated integrated the Janus particles with H2O2 solution,it's indicated that movement rate of Janus particles under 25? was obviously higher than that under 40 ?;The movement rate of Janus particles increased with the concentration of H2O2 solution.The rate of Janus particles in 30%H2O2 solution is 6 times in 10%H2O2 solution.