Evaporation-driven self-assembly of colloidal silica dispersion: new insights on janus particles.

The evaporation driven self-assembly of novel colloidal silica Janus particles was evaluated by scanning electron microscopy in comparison to unfunctionalized silica particles. The cyclodextrin- and azobenzene-modified compound was obtained utilizing Pickering emulsion approach, in which the particles were immobilized on solidified wax droplets and subsequently functionalized. Silica particles were modified with 3-aminopropyl trimethoxysilane and afterward reacted with tosyl-β-CD or phenylazo(benzoic acid), respectively. Mesoscopic structures of the colloidal dispersions, as dried films from aqueous solution, have been investigated by scanning electron microscopy and dynamic light scattering. Interestingly, it has been observed that the Janus particles show a significantly different evaporation-induced assembly than the unmodified particles.