Organosol stabilizer

In one example, colloidal Pd particles are obtained by the electrolysis of aqueous solutions of palladium chloride at pH 1 in a two-layer bath in the presence of a hydrocarbon solvent and epoxy dianic resin or PVA. Electrolysis results in flie formation of colloidal palladium organosols stabilized by the chemisorption of tiie polymer. Metal-lopolymers containing up to 90-95% of Pd remain after the removal of solvent and residual electrolyte. They are formed under high cathode polarization where concomitant elimination of hydrogen adsorbed on the nanoparticles (5.5-7.S nm in diameter) occurs. 

Typically the [NR4] -stabilized raw organosols contain 6-12 wt% metal but for metals such as rhodium they can be converted to pure colloids containing... 

Table 1. THF-stabilized organosols of early transition metals. (Reprinted from Ref. [53], 2007, with permission from Wiley-VCH.) Solvent Stabilized Early Transition Metal Colloids...

The catalytic applications of Moiseev s giant cationic palladium clusters have extensively been reviewed by Finke et al. [167], In a recent review chapter we have outlined the potential of surfactant-stabilized nanocolloids in the different fields of catalysis [53]. Our three-step precursor concept for the manufacture of heterogeneous egg-shell - nanocatalysts catalysts based on surfactant-stabilized organosols or hydrosols was developed in the 1990s [173-177] and has been fully elaborated in recent time as a standard procedure for the manufacture of egg-shell - nanometal catalysts, namely for the preparation of high-performance fuel cell catalysts. For details consult the following Refs. [53,181,387]. 

An organosol is the same mixture as described above, with the addition of solvent to reduce viscosity. These find their major applications in coatings. The solvent is evaporated before fusion of the film. Various pigments, colorants, stabilizers and fillers may be added, depending on the desired properties. Emulsion polymerization resins are generally employed because of their fast fusion rates. Coarser particle sized PVC resins would require extended time at the elevated temperature. 

The reduction of TiBr4-2THF with KfBEtjH] yields a hydrogen-free organosol Ti-0.5THF which seems to consist of very small Ti particles in the zerovalent state stabilized by THF molecules.83 This nanoparticulate metal colloid is extremely oxophilic, very soluble in THF but insoluble in hydrocarbons. 

Table 1 THF-Stabilized Organosols of Early Transition Metals...

Surface silanol groups of silica aquasols stabilized in an alkaline medium exchange protons for the alkaline ion such as Na+, K+, or NH4+ (Figure 13). The surface silanol groups can be esterified, as in silica organosols, or silanized (silylated) (Figure 14). Derivatization of the silica surface is the basis for the use of silica in analytical and process chromatography. 

Estabex . [Akzo Akzo Chem. BV] Epoxidized soybean oils or monooctyl ester plasticizer, stabilizer, fungicides for PVC, plastisol, organosol, surface coatings, inks, extruded prods., chlori-... 

Therm-Chek. [Ferto/Bedford] Light and heat stabilizers fix PVC, dastisols, organosols, rigid formulations, calendered, mold and extruded plasticized ccxnpositions. 

Fig. 2.9 Metal organosols accessible via the NR4(Bet3H) route (Eq. (2.2)). As synthesized, the [NR4P-stabilized raw organosols typically contain 6-12wt.% metal.

Fig. 2.10 Structural representation of NR4X-stabilized metal organosols. Reproduced with permission from Elsevier Science [91].

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