Study On The Preparation And Stability Of Reverse Phase Janus Emulsion

The inverse Janus emulsion,(W1+W2)/O droplet is composed by two separate chambers.The compositions of the two chambers are different and the shape of the two chambers is asymmetric,which makes anisotropic of the droplet in terms of both shape and composition.In addition,the droplets of the emulsion are composed of mutually independent and distinct microphase regions,which can selectively solubilize different functional molecules.The inverse Janus emulsion has potential applications in cosmetics,biomedicine,food etc.In the present thesis,the inverse phase anisotropic emulsion was prepared by traditional one-step vortex mixing.In addition,the topology of emulsion droplets can be controlled by the composition of emulsion.The inverse emulsion has smaller particle size,poor stability.They are sensitive to external condition.This instability is caused by the internal phase of the inverse emulsion,i.e.the water droplet.The inner phase has highly fluidity,allowing the system to have a relatively low flocculation energy barrier.This makes the emulsion sensitive to the difference of sedimentation force.The emulsion with large droplet size will produce greater sedimentation force leading to emulsion flocculation,stratification.Therefore,the mechanism of stability and destabilization is also discussed in order to expand the application of inverse Janus emulsion.Firstly,the partial phase diagram of FC-443O/C2H5OH/10%Na2CO3(aq)system was plotted at 25 ℃.The inverse Janus emulsion of FC-4430/C2H5OH/10%Na2CO3(aq)/VO system was prepared by vortex mixing of aqueous two-phase system(ATPS)and vegetable oil in the ATPS(1+1)region phase region within the phase diagram.The topological structure of the inverse Janus emulsiondroplet was characterized by microscope.The topological structure of inverse Janus emulsion wascontrolled by the mass ratio of surfactant FC-4430 to C2H5OH,and by the contant of 10%Na2CO3(aq).Secondly,The aqueous solution of inorganic salt(Na2CO3)with good biocompatibility and the low molecular alcohol(C2H5OH)were used to construct the ATPS.The inverse Janus emulsion of(Span 80+Tween 80)/C:H5OH/10%Na2CO3(aq)/VO system was formed by mixing the aqueous two-phase aqueous phase solubilized with Tween 80 and VO solubilized with Span 80.Thetopology of inverse Janus emulsion was controlled by changing the concentration of surfactantand the mass ratio of oil to water.At last,the stability and destabilization mechanism of inverse Janus emulsion wereinvestigated.The surfactant concentration and water/oil ratio were changed to control the stability.The results show that the large droplets become larger in the process of inverse phase Janus emulsion destabilization,due to the coalescence.Meanwhile the small droplets become smaller,which indicates that Ostwald ripening process in the emulsion.In addition,the curve of Turbiscan indicates the phenomenon of flocculation or coalescence in the demulsification process.We have to mention that,the Janus topology remains during the whole demulsification process.