Addition And Esterification Reactions In Emulsion Microreactors Of FC-770/n-heptane/H₂O

Anisotropic emulsions are composed of multiple oil phases with more than two independent micro-domains,and the droplets have asymmetric chemical composition,shape and properties.In the oil-water two-phase reaction,reactants with different chemical properties are selectively dissolved in different phase regions based on the principle of similar miscibility,and are transported between the water and oil phases and migrate to the oil-water interface for contact and collision.The entire reaction process is completed,and the reaction kinetics is regulated by regulating the contact area between the interfaces by regulating the topology of the anisotropic emulsion.Especially in the esterification reaction,the emulsion discharges the reaction product water out of the droplets in time to promote the forward reaction of the reaction.Due to its clear structural composition and minimal preparation process,researchers have been analyzing and exploring anisotropic emulsion microreactors for a long time.In this paper,polymer surfactants,nonionic surfactants and anionic surfactants are combined,and anisotropic emulsion microreactors are used in addition reactions,esterification reactions and cascade reactions to give anisotropic emulsions.Microreactor wider research direction and richer research content.The main researches are follows:(1)Anisotropic emulsion microreactor of FC-770/n-heptane/H2O(aq)system was prepared by selectively dissolving stilbene and NBS in n-heptane phase and water phase,respectively.By adjusting the volume ratio of oil phase,droplet particle size and surfactant type,the change rule of emulsion morphology was explored;and the change rule of reaction kinetics was summarized by the change of droplet morphology and reaction kinetics.An emulsion microreactor was constructed with anisotropic emulsion as carrier and used for the addition reaction of stilbene.Compared with the three-phase system and the single-side emulsion system,it is confirmed that the anisotropic emulsion emulsion system has a higher conversion rate.At the same time,the separation and recovery of products and excess reactants are achieved by emulsion breaking.(2)Taking advantage of the temperature-sensitive miscibility of hydrocarbon and fluorocarbon liquids,a temperature-responsive anisotropic emulsion microreactor was prepared,and the change from double to single-sided was achieved by temperature-induced droplets.Using the addition reaction experiment of stilbene as a model,the relationship between temperature and reaction kinetics was explored.Furthermore,it was proved that this reaction is a second-order reaction of two-molecular collision.At the same time,the Turbiscan instrument was used to monitor the in situ change of the anisotropic emulsion with time.The relationship between oil phase volume ratio and temperature and droplet settling rate is summarized.In addition,the pH-responsive regulation of anisotropic emulsions was achieved by introducing pH-responsive surfactants,and the kinetics of stilbene addition reaction using the microreactor as a carrier was preliminarily explored.(3)Stilbene,perfluoroheptanoic acid(PFHA)and NBS were dissolved in n-heptane,FC-770 and water,respectively,to realize the esterification reaction and the addition-esterification cascade reaction in anisotropic Occurrence in emulsion microreactors.It should be noted that the conversion rate of the esterification reaction is much higher than that of the usual esterification reaction due to the drainage effect of the emulsion droplets.We also explored the effect of reactants on droplet morphology and the effect of surfactant concentration and species on reaction kinetics.