Assembly of latex particles by using emulsion droplets as templates .2. Ball-like and composite aggregates

We report data on using the emulsion-based method for the assembly of ball-like aggregates of a positively charged (amidine) latex. The latex particles are strongly hydrophobized with the use of sodium dodecyl sulfate, which induces their adsorption into the bulk of the emulsion droplets. The droplets are then sterically protected against coalescence, and the particles gathered inside them are fixed. After the emulsion droplets are dissolved, a suspension of ball-like latex aggregates is obtained. The aggregates do not appear to be ordered, but their overall shape is precisely spherical. The process of fabricating ball-like aggregates was then combined with the assembly scheme for hollow supraparticles (presented in the first paper of this series). As a result, we have been able to obtain composite particles, whose cores are ball-like aggregates of amidine latex, surrounded by a shell of negatively charged sulfate latex. The core-shell structure was visualized by fluorescent microscopy. We also report data on the fabrication of composite particles by amidine heterocoagulation over hollow spherical shells from the sulfate latex. The described methods seem applicable to the assembly of ball-like and composite aggregates from colloid species other than latex beads.