Self-assembly of a short amphiphile in water controlled by superchaotropic polyoxometalates: H4SiW12O40 vs. H3PW12O40

Nanometric ions, such as polyoxometalates (POMs) or ionic boron clusters, with low charge density have previously shown a strong propensity to bind macrocycles and adsorb neutral surfaces: micellar, surfactant covered water–air polymer surfaces. These association phenomena were arise from solvent-mediated effect called the (super-)chaotropic effect. We show here by combining cloud point (CP) measurements, scattering (SAXS/SANS) spectroscopic techniques (NMR) that Keggin POMs: H 4 SiW 12 O 40 (SiW) 3 PW (PW), induce self-assembly of an organic solvent: dipropylene glycol n -propylether (C P 2 ), in water. The interaction between SiW/PW C leads drastic increase CP, aqueous solubility, , e.g. enables reaching full water-C co-miscibility at room temperature. At high POM concentrations, continuous forming SiW-[C ] 1-2 complexes, whereas produces decrease CP attributed formation nearly “dry” spherical [PW] [C m colloids, ~ 30. /PW contents, colloids turn into large interconnected structures, delimiting two pseudo-phases: PW-C -rich phase water-rich phase. It is proposed stronger electrostatic repulsions (4?), compared (3?), prevents mesoscopic colloids.