Preparation of Poly(Ionic Liquid) Microbeads by Evaporation-Assisted Phase Separation

The authors reported a simple and high-yield evaporation-assisted phase separation (EAPS) method to prepare poly(ionic liquid) (PIL) microbeads, in particular submicron microbeads. Irregular PIL powder or bulk is dissolved in a theta solvent composed of volatile good solvent and less volatile non-solvent at room temperature, and then PIL microbeads are formed by evaporation of the solution at a temperature lower than the boiling point of volatile good solvent. The yield of microbeads, in particular, submicron microbeads, prepared by the EAPS method can reach 99%. The mechanism of microbead formation is studied by tracing the nucleation and growth process by the light transmittance. The key parameters to control the size and morphology of microbeads are investigated and discussed.