Assembly of Latex Particles by Using Emulsion Droplets as Templates. 2. Ball-like and Composite Aggregates

Wereport data onusing the emulsion-basedmethod for theassembly of ball-like aggregates of apositively 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 stericallyprotectedagainst coalescence, and theparticles gathered inside themare fixed. After theemulsion 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). Asa result,wehavebeenable to obtain compositeparticles,whose coresareball-likeaggregates 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.