Shear-Assisted Preparation Of Amphiphilic Block Copolymer Particles And Their Properties Study

In recent years,agglomerate particles formed by amphiphilic block copolymer have shown great application potential in biomedicine,chemical catalyst and optoelectronic,and have become a hotspot in polymer science research.Many preparative technique such as self-assembly?nano-precipitation?electrospinning and microfluidics have been extensively studied,but these techniques were more or less deficient and limited in application.As a method for preparing micro/nano polymer linear structure,liquidliquid shear technique have been praised by researcher because of its simple and efficient characteristics.Amphiphilic block copolymer have many different properties compared with homopolymers.In this paper,we have studied the effects of amphiphilic block copolymers on the deformation process in the shear laminar flow field of viscous medium,and explores some simple applications of the prepared agglomerate structure.The main contents and conclusions are as follows.1?Atom transfer radical polymerization(ATRP)and ring-opening polymerization(ROP)were used to synthesis amphiphilic block copolymer with different molecular constitution and structure.Synthetic copolymers including poly(ethylene glycol)-bpolystyrene(PEG-b-PS),poly(ethylene glycol)-b-poly(methyl methacrylate)(PEG-bPMMA),poly(ethylene glycol)-b-poly(tert-butyl acrylate)and ?-poly(ethylene glycol)-b-polystyrene-b-poly(methyl methacrylate)(?-PEG-b-PS-b-PMMA)were characterized by ~1H NMR and GPC.2?We investigated the effect of different experimental conditions on the deformation process of PEG-b-PS under shear agitation.It is found that the hydrophilic/hydrophobic ratio has little effect on its structural morphology,which mainly affects the deformation by the entanglement of the molecular chains in the solution.It can adjust the size of the rod-like particles by changing the concentration of the polymer solution and the stirring speed.Different dispersion media and solvent also affect deformation process by affecting the rate of solvent exchange.Among them,sheet-like agglomerates can be obtained when ethylene glycol as the dispersion medium,and if THF or DMF as the solvent spherical agglomerates can be obtained.Through the XPS and TEM it was proved that the microstructure of the agglomerates was the outer part of the PEG chain,and some of the internal nano-domains similar to the micelles.3?We compared the results of different block copolymers to explore the effect of the properties of the segments on the morphology of agglomerates.It was found that agglomerates with hollow spherical structures can be prepared from PEG45-b-PCL225 in THF as solvent and their morphology were affected by the proportion of hydrophobic segments.On the other hand,we compared different block copolymer in which PMMA,PCL,PtBA as hydrophobic chain and 3-miktoarm terpolymer,it was found that Tg of the hydrophobic segment has a great influence on the morphology.The hydrophobic segment with higher Tg at room temperature is favorable for the formation of a linear structure with stable rigidity,while low Tg results unstable and irregular structure,such as PEG45-b-PtBA133 would get irregular morphology of the aggregate.4? We explored the application of agglomerates in copolymer composites and demulsification.PEG45-b-PS143 rod-like agglomerates coated with nano-SiO2 can be obtained by a process similar to that of nanoprecipitation,and the coating rate of up to 90% or more can be achieved surprisingly.On the other hand,the crosslinking sheetlike agglomerates can be obtained from the modified PEG45-b-PS143.The addition of sheet-like agglomerates to an oil-in-water emulsion formed from hexadecane,water and sodium dodecyl sulfate(SDS)allows rapid separation of hexadecane from the emulsion with a strong demulsification effect,which may have potential applications in the separation of oil from emulsions.