The Research For Pickering Emulsion Droplets As Microreactor With Light And Magnetic Responses

The microreactor is a kind of green reactors with micro meter size,low power consumption,high yield,sensitive response,which is widely applied in heat exchange,mixing,and separation of the various functions of the highly integrated micro reaction system.Nevertheless,the high cost of the equipment and the complicated preparation process restrict its wide application in industrial production fields.The so called Pickering emulsion is stabilized solely by solid particles.Compared with the well-known surfactant-based emulsions,Pickering emulsion with high stability,non-toxic,environmental friendly has aroused great interest of the reserchers in the recent years.Hower,there is no well-known marketed product or material where the utilization of Pickering emulsion is claimed.The reason is that Pickering emulsion has only recently been recognized as a technology which could be considered as distinct of an emulsifier-based emulsion.How to utlize the Pickering emulsion technology and microreactor technology to expand its application in the industrial fields and how to enhance the intelligent response ability of the microreactor to adapt to the complicated industrial process have important scientific significance.The purpose of this project is to realize reversible Pickering emulsion phase inversion by UV/Dark stimulation.Furthermore,the emulsion microreactor with light response and the microreactor with light and magnetic response are designed to provide reliable reference for improving the intelligent response of the microreactor.In the study of the reversible Pickering emulsion phase inversion by UV stimulation,the author describes a kind of smart TiO2 nanoparticle emulsifiers.By tuning the surface wettability of TiO2 nanofarticles in situ with UV/Dark activation,emulsions stabilized by the nanoparticles can be reversibly switched between water-in-oil type and oil-in-water type,the smart TiO2 nanoparticle emulsifiers can be settled in either oil or water phase as desire when phase-separation,therefore convenient for recycling.UV irradiation is used to awaken the dormant TiO2 emulsifiers in situ,based on the degradation of the grafted long-chain silanes(dormant state)into short ones(awakened state).Interestingly,if the TiO2 emulsifiers are treated with UV irradiation later on,they gradually become activated ones,presumably as a result of the UV-induced adsorption of hydroxyl groups on the surface of Ti02 emulsifiers.The simple,clean and neat light stimulation is the only driving force in the whole process.As repected,most of the emulsifiers were dispersed in oil/water due to their wettability,and the percent recovery from oil/water was 71.6/79.6,respectively.In the research of emulsion microreactor with light response,the author successfully prepared the emulsion microreactor stabilized by Ti02 nanoparticles,which has the ability of UV light response.The microreactor was loaded with alkaline methyl orange solution and dilute hydrochloric acid,respectively.The emulsion microreactors coalescenced and triggered acid-base neutralization reaction under UV irradiation.The research showed that oil phase volume fraction determined the droplet diameter distribution of the emulsions.When the oil phase volume fraction was 50%,the size of the droplets was appropriate.In addition,particle concentration directly affected the size and stability of emulsion droplets.When the particle concentration was less than 1%,it could not form a stable emulsion.Interestingly,systematic research revealed that the higher the concentration was,the smaller size of the droplets was.Furthermore,the TiO2 nanoparticle doped with N element led to the red shift of the wavelength absorption,which could absorb visible light.In the research of emulsion microreactor with light and magnetic response,the sol-gel method and the co-precipitation method were used to prepare Fe3O4@Ti02 composite nanoparticles.The emulsion microreactor with light and magnetic responses was successfully loaded with sodium alginate and calcium chloride,respectively.The emulsion microreactor had directional movement(magnetic response)in the presence of an external magnetic field.By tuning the surface wettability of Fe3O4@TiO2 composite nanoparticles in situ with UV actuation(light resoponse),the emulsion microreactor broke and aggregated to realize reaction of A+B=C reaction.Therefore,the calcium alginate had gained.The study also found that the Fe3O4@TiO2 composite nanoparticles had core-shell structure,the core of Fe3O4 nanoparticles were coated by TiO2 shell,of which the diameter was about 25nm.The studies have shown that the switchable emulsions and the intelligent response emulsion microreactor have good prospects in the cosmetic,food,pharmaceutical industry and the field of controlled release emulsions.