Latex Assembly

Charged latex is a good building block for an electrostatic layer-by-layer assembly. Positively or negatively charged monodisperse lattices with diameters of 30, 40, 45, 50, or 75-nm and with different colors are commercially available, for example, from Seradyn Inc. or IDC-Ultraclean Uniform Latex Inc. For the first time, a multilayer assembly of negative latex spheres (carboxyl-modified or sulfate polystyrene) in alternation with positive latex (amidine-modified polystyrene) was reported by Bliznyuk and Tsukruk [57]. They have described a strong tethering of charged nanoparticles to the surface, which prevents surface diffusion and the rearrangement required for formation of perfect lateral ordering. This situation is different from the one with the formation of the ordered 3D-mesocrystals by slow crystallization of the monodispersed aqueous colloids [72]. In the nanoparticle/polyion multilayers, one loses the crystallike ordering, but gains control of the process, preparing multilayers of close-packed nanoparticles with a precisely known number of monolayers. We demonstrated a regular layer-by-layer assembly of carboxylated 45-nm diameter Ser-adyn latex in alternation with PEI.

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