Silica/polystyrene bipod-like submicron colloids synthesized by seed-growth dispersion polymerisation as precursors for two-patch silica particles

Abstract

We report the synthesis at the gram scale of spherical silica particles bearing two organic patches made of grafted polystyrene chains at their poles. The patchy character of the particles is evidenced by combining transmission electron microscopy analysis and electron energy-loss spectroscopy. The multi-stage synthesis is based on the fabrication of silica/polystyrene bipods by dispersion polymerisation followed by the selective dissolution of the polymeric nodules, and leads to about 70% pure batches. The morphological purity is increased up to 98% by flow cytometry experiments. The polyethylenimine used as a stabiliser in the polymerisation step seems to play an important role in the detection of patches since the latter proved unsuccessful for particles obtained in the presence of polyvinylpyrrolidone.