Preparation and Properties of Poly (Ionic Liquid)s Based Janus Composite Particles

Author:Tang Xiu Ping

Supervisor:song xi ming

Database:Doctor

Degree Year:2019

Download:88

Pages:131

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Janus particle is a kind of special material with asymmetry in composition and structure.The physical or chemical properties of two different surfaces of the particle are different,which makes it have a very broad application prospect in many fields,such as solid particle emulsifier,color display,biomedicine and so on.Janus materials have two regions on the same object with different chemical compositions generally.The surface wettability can be adjusted with selective chemical modification.The as-prepared Janus materials can be particle emulsifier to get stable Pickering emulsions in water or oil/ionic liquid system.Polyionic liquid(PILs)is a kind of polyelectrolyte formed by ionic liquid monomer as repeating unit.The designability and ion-exchangeability of monomer unit are conducive to the accurate design of functional materials for specific targets.To extend the functionality of Janus materials,in this paper,several types of Janus materials with PILs groups on one side were prepared by various methods and the preparation methods of Janus materials based on PILs were developed.The as-prepared Janus materials with the characteristics of the PILs were applied to two types of the Pickering emulsion catalytic system.The main research contents of this paper are as follows:(1)A Pickering emulsion enzyme catalyzed system was constructed by Janus particles based on the PILs.Snowman-like SiO2@PDVB/PS Janus particle was synthesized by seed emulsion polymerization.Poly(1-vinyl-3-ethylimidazolium bromide)functionalized silica@PS/PDVB Janus particles were synthesized by atom transfer radical polymerization(ATRP).The particle morphology and structure of PILs-SiO2@PDVB/PS Janus were studied by SEM,TEM,XPS and Zeta potential analysis.The results showed that the phosphor-tungstic acid was successfully loaded onto the Janus particles and the original morphology of SiO2@PDVB/PS Janus particles was maintained.The PILs-SiO2@PDVB/PS were employed as solid surfactant to emulsify water and toluene.The obtained Pickering emulsion was the water-in-oil type.The lipase was loaded into the water phase of the Pickering emulsion,which was applied in biphasic enzymatic catalysis system.Compared with the lipase-catalyzed oil-water phase,the specific activity of the enzyme in the Pickering emulsion catalyst system was increased by 6 times.Furthermore,the recyclability of lipase in Pickering emulsion system was effectively realized.After 8cycles of reaction,the enzymatic activity retention rate of the enzyme-loaded Pickering emulsion catalyst system was still by more than 90%.With the increase of PILs-SiO2@PDVB/PS Janus particles,the enzyme specific activity of Pickering emulsion system reflected a concomitant increase.(2)A stable non-aqueous Pickering emulsion catalytic system was constructed by the Janus particles based on the PILs.The catalyst H3PW12O40(PA)was immobilized on PIL-modified JPs by anion-exchanging.The particle morphology and structure of PA-PILs-SiO2@PDVB/PS Janus were studied by SEM,TEM,XPS and Zeta potential analysis.The results showed that the phosphor-tungstic acid successfully loaded onto the Janus particles and the original morphology of SiO2@PDVB/PS Janus particles was kept.The PA-PILs-SiO2@PDVB/PS were employed to emulsify[BMIM]BF4 and toluene as solid surfactant.The obtained Pickering emulsion was the IL-in-oil type.A continuous non-aqueous flow Pickering emulsion interface catalysis(FPIC)system was obtained by filling the[BMIM]BF4/toluene Pickering emulsion into a column reactor.The catalytic properties of the FPIC system were studied with toluene and acetic anhydride as the substrate.The FPIC column systems showed a relatively higher conversion.The conversion of acetic anhydride is as high as 95.3%.The catalytic activity did not decrease significantly and the morphology of the emulsion droplets was intact and not damaged through 40 h continuous reaction.After six times of cyclic catalysis,the initial catalytic activity maintained basically.The catalyst could be recovered by simple centrifugation,and the recovered particles still showed good emulsifying performance.(3)The tunable morphology and amphiphilicity PILs-based Janus particles were prepared.Poly(benzyl ethyl trimethyl ammonium hexafluorophosphate)(PVTMAPF6)and poly(4-chloromethyl styrene)(PCMS)microspheres were synthesized by dispersion polymerization.The composite particles of SiO2@PVTMAPF6 and SiO2@PCMS were synthesized by seed emulsion polymerization using a silane coupling agent MPS against PVTMAPF6 and PCMS particle,respectively.The particle morphology and structure were studied by SEM,TEM,XPS and Zeta potential analysis.After SiO2@PVTMAPF6 particles was synthesized by seed emulsion polymerization,the particle morphology changed to be strawberry-like and the SiO2 particles attached onto the surface of the PVTMAPF6 seed particle.Using the PCMS particle as a seed,the SiO2@PCMS composite snowman-like Janus particles were synthesized by seed emulsion polymerization.The sizes of the silica bulge were tunable(100-700 nm).The surface of the SiO2 hemisphere of SiO2@PCMS Janus particles had a large amount of-OH groups,which could react with different silane coupling agents.On the other side,the surface of PCMS had many chloromethyl groups,which could react with N-methylimidazole and other nitrogenous compounds.OTES-SiO2@PCMS/Cl-and NH2-SiO2@PCMS/PF6-were successfully synthesized by the above method.NH2-SiO2@PCMS/PF6-Janus particles can emulsify oil and water two-phase system.OTES-SiO2@PCMS/Cl-can emulsify oil/water and oil/ionic liquid two-phase systems.The stability of the emulsions could be controlled by changing the ionic environment in the water phase.