Résumé
Two ways have been explored to impart to nanosize self-assembled colloidal particles the ability to assemble further into clusters: the first one relies on coordination chemistry and the second relies on non-uniform charge distribution. Scattering experiments have been analyzed either in terms of effective potential to determine the amplitude and range the short range attractive contribution, or in terms of aggregation number of the resulting clusters. Mixed surfactant micelles have been functionalized by chelating groups, using specifically designed complexing surfactants. Functionnalizing the micelles in such a way first enhances the repulsive interactions, but those are switched to attractive ones in the presence of coordination centers such as aluminum cations. This is revealed by the strong increase of scattering intensity at low q. A square well potential allows accounting for the structure factor of such systems. The range of attractive interaction depends solely on the molecular size of the complexing surfactant, while the concentration of coordination centers and the pH determine the depth of the well, probably through the condensation state of the polycations. Increassing attraction leads to clusters with aggregation numbers up to 12, before reaching the stability limit of the system.Patchy charged nano-sized particles have been designed by doping initially neutral micro-emulsion droplets by gemini type cationic surfactants. Three-charge and four-charge surfactants with either linear or branched polar backbone have been used as dopants. Bromide specific potentiometry reveals higher counter-ions condensation on patchy charged colloids. The structure factors of these patchy charged micro-emulsions suggest that peculiar distributions of charges induce short range attraction inducing clustering with aggregation number up to 6 with monovalent couter-ions but that could be increase using divalent ones.Both approaches show that supracolloidal colloidal clusters are certainly accessible through assembling strategies at equilibrium, but it certainly requires fine control on the antagonistic interactions involved.