Investigation Of Emulsification Behavior And The Derived Materials Using Janus Particles

Janus materials composed of two different components and structures,can achieve various functions by compounding different materials.In this investigation,the amphiphilic snowman-like Janus particles were used as solid surfactant to stabilize the oil-water interface and form a stable Pickering emulsion.By adjusting the ratio of oil-water,different microstructures and types of emulsions were obtained.The microstructure of emulsion system and the interfacial aggregation structure of Janus particles during the phase transition were studied.Furthermore,the orientated interface was further fixed and interconnected to construct superstructures which possessed Janus characteristics by emulsion interface in-situ materialization.Thus,the Janus Colloidosomes,through-hole materials and bi-continuous amphiphilic porous materials were obtained,respectively.1.Amphiphilic snowman-like silica@PDVB/PS Janus particles were used as solid particle surfactants for stabilizing Pickering emulsions.The effect of oil-water ratio on the microstructures and types of the emulsion was studied.Water-in-oil,oil-in-water and bi-continuous structures were obtained respectively.The transformation of emulsions was detected by rheology and electrochemical tests and the microstructure of the emulsions and the aggregation structure of Janus particles were characterized by optical microscope and SEM.The monolayered Janus particles were orientated at the emulsion interface,and the hydrophilic SiO₂ side faced the water phase while the hydrophobic PDVB/PS side faced the oil phase.2.A stable water-in-oil emulsion was formed by using the amphiphilic silica@PDVB/PS Janus particles as surfactants and paraffin（T_m=52-54°C）as dispersed phase.Janus particles arranged in a single layer on the surface of paraffin wax,and the side of amino-modified SiO₂ was toward the water phase.The Janus particles were crosslinked within oxidized dextran aqueous solution and react with amino groups on the surface of SiO₂ via Schiff base reaction.Janus Colloidosomes with hydrophilic outer surface and lipophilic inner surface were obtained by removing paraffin phase.These Janus Colloidosomes can selectively capture oil-soluble components into their cavities from water to achieve oil-water separation.It should be noted that this method was universal.Janus particles were used to stabilize water-in-toluene emulsion and the reversible toluene-in-water emulsion.Further through the in-situ biphasic redox polymerization of AA and DVB monomer at the interface,Janus Colloidosomes with hydrophilic outer surface and lipophilic inner surface were obtained.And the opposite structured Janus Colloidosomes were also obtained with the reversible emulsion.3.Based on the high internal phase Pickering emulsion stabilized by amphiphilic silica@PDVB/PS Janus particles,a through-hole material was constructed.The Janus particles were used to stabilize water and DVB monomer to form the oil-in-water high internal phase emulsion.The volume ratio of the dispersed phase was as high as 88%,and the amount of Janus particles was 0.2 wt%.Hydrophobic DVB monomer was polymerized to obtain porous amphiphilic materials which possessed hydrophilic through-pore channels.The bulk phase can adsorb oily components,and hydrophilic channels can facilitate the flow of water,thus effectively realizing oil-water separation.The SiO₂ side of Janus particles in the channel can be functionalized by modifying different functional groups,such as amino modified SiO₂ side,which can selectively adsorb heavy metal Cr⁶⁺ions in the water.4.The bi-continuous amphiphilic porous materials were constructed based on the bi-continuous emulsion emulsified by the amphiphilic silica@PDVB/PS Janus particles.Bi-continuous emulsion was obtained by adjusting the oil-water ratio to stabilize the water and toluene system with Janus particles.The hydrophilic monomer AA and lipophilic monomer DVB were dissolved in water and oil phase respectively,and the Janus particles were fixed via in-situ redox polymerization at the interface to form a continuous network.The SiO₂ side of the Janus particles connected with PAA faced to water phase,while the PDVB/PS side of the Janus particles connected with PDVB faced to oil phase.Porous materials with hydrophilic and lipophilic channels were prepared.Because amphiphilic channels co-exist simultaneously in the porous material,it can be infiltrated with both hydrophobic and hydrophilic solvents.