Preparation of Poly(Ionic Liquid) Particles with Anionic Side Chain by Dispersion Polymerization.

Micrometer-sized poly(ionic liquid) (PIL) particles with an anionic side chain, poly(1-butyl-3-methylimidazolium 3-sulfopropyl methacrylate) (poly([Bmim][SPMT])), are successfully prepared by dispersion polymerization at 60 °C in ethanol/ethyl acetate (2/8, w/w) with poly(vinylpyrrolidone) as a stabilizer. However, the obtained particles do not maintain the particulate state during drying at room temperature due to poly([Bmim][SPMT])'s low glass-transition temperature, below room temperature. In order to prevent coalescence and maintain particle shape, a cross-linking monomer is added after the nucleation stage of dispersion polymerization. Moreover, Fourier-transform infrared spectroscopy (FT-IR) demonstrates cation exchange between the obtained particles and metal cations (Ag+ ).

Emulsion Polymerization with a Biosurfactant.

Emulsion polymerization of styrene was conducted using a biosurfactant (i.e., sodium surfactin, hereinafter called just "surfactin") having very low critical micelle concentration (CMC, 2.9 × 10-3 mmol/L) and biodegradability characteristics. The nucleation mechanism was investigated by comparing with a conventional surfactant (i.e., sodium dodecyl sulfate) system. Unlike the emulsion polymerization systems using conventional surfactants, nucleation mechanisms changed above CMC in the presence of a biosurfactant. At low concentrations of surfactin (above CMC), the polystyrene (PS) particles are likely generated via a soap-free emulsion polymerization mechanism. In contrast, at high surfactin concentrations, the PS particles would be synthesized by following a micellar nucleation mechanism. However, the slope (0.23) of the log Np versus log Cs plot (Np: number of particles; Cs: concentration of surfactin) did not obey the Smith-Ewart theory (0.6), this probably being produced by the high adsorbability of surfactin.