Kinetically Controlled Self-Assembly of Latex-Microgel Core-Satellite Particles

Latex-microgel core-satellite particles were prepared by electrostatic assembly of negatively charged polystyrene latex and positively charged microgels of a poly(N-isopropylmethacrylamide) (pNIPMAM) and poly[2-methacryloyloxy)ethyl] trimethylammonium chloride (pMETAC) copolymer. The number of satellites per core, determined by scanning electron microscopy, varied from 3 to 10 depending on the sizes of the microgel and latex microparticles. The numbers of satellites per core for different size ratios were compared with the predictions for thermodynamically controlled (maximum packing) and kinetically controlled (random sequential adsorption) assembly, and it was shown that the assembly of latex and microgel proceeds through a random sequential adsorption mechanism. The charges of the microgels and latex particles were retained within the assemblies; therefore, the core-satellite particles have well-defined regions of positive and negative charge. These regions were used to direct the adsorption of gold and latex nanoparticles of opposite charge in order to create multicomponent colloids.