New Janus Particles and Pickering Emulsions for Superhydropobic Surfaces

This research presents an in-situ functionalization of silica nanoparticles in oil-in-water (o/w) biphasic system with two equimolar organosilanes of antagonistic polarity. Homogeneous and stable Pickering emulsions have been obtained, where droplet size can be tuned according to the silica particle concentration and the o/w ratio used. The introduction of organosilanes to the system results in the formation of silica based colloidosomes due to crosslinking of the silica particles by polysiloxane that is formed due to polycondensation of the organosilanes. The introduction of carbon nanotubes (CNT) to the silica based Pickering emulsion enabled us to prepare electrically conductive CNT/silica nanohybrid colloidosomes with controlled porosity. CNTs and silica nanoparticles both are located in the interface, as evidenced by confocal laser scanning microscopy and cryo-SEM. After drying, hierarchical porous structures have been generated spanning the micro, nano, and macropore range. The resulting porous structures have shown clear behaviour of superhydropobicity due to their ordered nano and micron scale roughness. The studied Pickering emulsions have been applied successfully on polycarbonate, polypropylene, polyethylenterephthalat and polyvinylchlorid as superhydropobic coatings.

Additionally, we present new, rapid and facile approach for the synthesis of Janus particles via polymer precipitation process, resulting in core-shell structure that allows for selective chemical modification of the exposed hemispheres of the particles. The particles are immobilized onto highly rigid polymeric microspheres such as polycarbonate which may pave the way to the development of a robust fabrication procedure. Fluorinated Janus particles and silica functionalized nanoparticles were incorporated in PE polymer matrix during extrusion procedure. The resulting PE surface has shown clear superhydrophobic behaviour.