Preparation Of Imidazolium Based Poly (Ionic Liquid) Microspheres And Their Electrorheological Stimuli Response

As a smart soft material,electrorheological(ER)fluids are suspensions in non-conducting liquids with semiconducting or electrically polarizable particles,of which rheological properties change drastically when an external electric field is employed.Unfortunately,the industrial applications of ER fluids are limited by the shortcomings of low field-induced yield stress,large leaking current,and suspension instability.In this paper,several different monomer unit structures of the imidazolium-based PIL microspheres were prepared by a simple dispersion polymerization and their electrorheological properties were studied.Firstly,micron-sized linear poly(ionic liquid)(PIL)particles,poly(1-butyl-3-vinylimidazolium tetrafluoroborate),poly(1-octyl-3-vinylimidazolium tetrafluoroborate)and poly(1-dodecyl-3-vinylimidazolium tetrafluoroborate)particles,were synthesized by dispersion polymerization.Morphologies,chemical structures and thermal properties PIL microspheres were detected by SEM,1H NMR,FT-IR and TG respectively.The result of XRD shows that PIL particles are amorphous.The elecctrorheological properties of the PIL electrorheological fluids ER were measured via rotational rheometer at various electric field strengths,which exhibited a typical ER performance.Secondly,micron-sized cross-linked poly(ionic liquid)particles(CLPIL)by dispersion polymerization.Mechanism of polymerization is the conventional radical copolymerization of a imidazolium-based IL(Im IL)monomer and the cross-linkers ethylene glycol dimethacrylate(EGDMA)and 1,6-hexanediyl-3,3'-bis-1-viny-limi dazolium ditetrafluoroborate([HVIm][BF4])in selective solvents.The elecctrorheological properties of the PIL were measured by rotational rheometer at various electric field strengths,which exhibited a classic ER performance.The shear stress curves were fitted to the Cho-Choi-Jhon(CCJ)model of the rheological equation of state.