Simple route to prepare stable liquid marbles using poly(ionic liquid)s

Abstract

Individual “liquid marbles” were prepared by encapsulation of water droplets using flocculated polymer latexes stabilized with poly(ionic liquid)s. At first, the emulsion polymerization of poly(styrene) and poly(methyl methacrylate) using different poly(ionic liquid)s as stabilizers was investigated. Stable latexes composed of spherical polymer particles with sizes ranging between 300 and 700 nm as characterized by dynamic light scattering and scanning electron microscopy were obtained. Subsequently, the polymer particles were flocculated by anion exchange precipitation of the poly(ionic liquid)s provoked by the addition of lithium bis(trifluoromethanesulfonyl)imide salt. After simple filtration and drying processes, the flocculated latexes led to hydrophobic powders with similar micrograin size compared to the original latexes. Very stable “liquid marbles” were prepared by gently shaking water droplets of different volumes onto the hydrophobic powders. The morphology and stability of the liquid marbles were characterized by optical and confocal microscopy.