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

JOURNAL OF COLLOID AND INTERFACE SCIENCE

卷:587

Article

Schmid, Philipp^1,2  Buchecker, Thomas^1,2  Khoshsima, Ali^3,4  Touraud, Didier^2,4  Diat, Olivier²  Kunz, Werner^2,4  Pfitzner, Arno¹  Bauduin, Pierre² 

[1] Univ Regensburg, Inst Inorgan Chem, D-93040 Regensburg, Germany

[2] Univ Montpellier, CNRS, ENSCM, ICSM,CEA,Inst Chim Separat Marcoule, Marcoule, France

[3] Hakim Sabzevari Univ, Sch Petr & Chem Engn, Sabzevar, Iran

[4] Univ Regensburg, Inst Phys & Theoret Chem, D-93040 Regensburg, Germany

关键词: Superchaotropicity;    Polyoxometalates;    Mesoscopic structuring;    Colloids;    Adsorption;    Self-assembly;   

DOI  :  10.1016/j.jcis.2020.12.003

来源: Elsevier

【 摘 要 】

Nanometric ions, such as polyoxometalates (POMs) or ionic boron clusters, with low charge density have previously shown a strong propensity to bind to macrocycles and to adsorb to neutral surfaces: micellar, surfactant covered water-air and polymer surfaces. These association phenomena were shown to arise from a solvent-mediated effect called the (super-)chaotropic effect. We show here by combining cloud point (CP) measurements, scattering (SAXS/SANS) and spectroscopic techniques (NMR) that Keggin POMs: H4SiW12O40 (SiW) and H3PW12O40 (PW), induce the self-assembly of an organic solvent: dipropylene glycol n-propylether (C3P2), in water. The strong interaction between SiW/PW with C3P2 leads to a drastic increase in the CP, and aqueous solubility, of C3P2, e.g. SiW enables reaching full water-C3P2 co-miscibility at room temperature. At high POM concentrations, SiW leads to a continuous increase of the CP, forming SiW-[C3P2](1-2) complexes, whereas PW produces a decrease in the CP attributed to the formation of nearly dry spherical [PW]n[C3P2]m colloids, with n similar to 4 and m similar to 30. At high C3P2/PW contents, the [PW]n[C3P2]m colloids turn into large interconnected structures, delimiting two pseudo-phases: a PW-C3P2-rich phase and a water-rich phase. It is proposed that the stronger electrostatic repulsions between SiW (4-), compared to PW (3-), prevents the formation of mesoscopic colloids. (c) 2020 Elsevier Inc. All rights reserved.

【 授权许可】

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