Hollow Poly(ionic liquid)/α-Al₂O₃ Composite Particles Prepared by Microwave-Assisted Pickering Emulsion Polymerization and Their Electrorheological Polishing Property

In this study, we reported a kind of hollow poly(ionic liquid)/α-Al₂O₃ composite particles prepared by rapid microwave-assisted Pickering emulsion polymerization using the commercial high hardness α-Al₂O₃ abrasive (Mohs hardness = 9) as a particulate surfactant. The structure and morphology were characterized by different techniques. The as-prepared composite particles were then used as the dispersed phase of the electrorheological polishing fluid. Our results demonstrated that the hollow poly(ionic liquid) core provided dispersion stability and electrorheological effect, while the α-Al₂O₃ shell provided high hardness and polishing capability. Under an electric voltage of 3 kV, the polishing fluid of the hollow poly(ionic liquid)/α-Al₂O₃ composite particles could improve the surface quality of the stainless-steel workpiece with Mohs hardness of 5 from Ra ∼270 to ∼90 nm. This polishing performance was extraordinary and far better when compared to that of the polishing fluid consisting of a simple mixture of poly(ionic liquid) particles and α-Al₂O₃ particles. During polishing, the voltage, rotation speed, working gap, and polishing time were demonstrated to have an effect on polishing efficiency. This study paves the way to develop electrorheological polishing fluids with dispersion stability and high polishing efficiency by combining hollow polymer particles and high hardness of abrasives.