Monometallic and bimetallic colloids were prepared in micelles of the block copolymer polystyrene-b-poly-4-vinylpyridine in toluene and analyzed by electron microscopy and various techniques of X-ray analysis. These metal colloids were studied in hydrogenation of cyclohexene, 1,3-cyclooctadiene, and 1,3-cyclohexadiene. A strong influence of the synthetic pathway to the colloids and the type of reducing agent on the catalytic activity of the colloids was found. The lowest activity was observed for N2H4·H2O reduction which is related to a morphology where only a small number of noble-metal colloids is embedded in the micelle core. The highest activity was obtained for the super-hydride reduction where the data suggest the existence of many metal clusters per micelle. The bimetallic Au/Pd colloids with metal ratios 1/5, 1/4, and 1/3 show the highest activity in hydrogenation of cyclohexene to cyclohexane. The Pd monometallic and Au/Pd bimetallic colloids are also rather selective catalysts (both in the homogeneous and a heterogeneous modification), as shown by the hydrogenation of 1,3-cyclooctadiene and 1,3-cyclohexadiene to the corresponding cycloalkenes.

The interaction of the amphiphilic block copolymer, polystyrene-block-poly(ethylene oxide) (PS-b-PEO), with cationic surfactant, cetylpyridinium chloride (CPC), in aqueous media was studied by static light scattering and analytical ultracentrifugation. Three well-defined populations of hybrid structures corresponding to micelles, micellar clusters, and supermicellar aggregates were found to exist in the PS-b-PEO/CPC aqueous solutions at a block copolymer concentration of 10 g/L. The relative ratio of each type of structure and their parameters strongly depend on the CPC concentration, mobility of the polystyrene micellar core, and chemical composition of the dispersing media. Ion exchange of the surfactant counterions in the hybrid PS-b-PEO/CPC system by PtCl6 2-and PdCl4 2-ions resulted in saturation of the micellar structures with noble metal ions. The subsequent reduction of the metal-containing PS-b-PEO/CPC/MXn species with NaBH4 and molecular hydrogen resulted in the formation of metal nanoparticles mainly located in the block copolymer micelles.

The formation of micelles, micellar clusters, and aggregates in aqueous solutions of polystyrene-blockpoly(ethylene oxide) macromolecules (PS-b-PEO) in the presence of various additives is studied. Behavior of the PS-b-PEO micellar solutions is examined with static light scattering and sedimentation in the ultracentrifuge. Sedimentograms of the solution of PS-b-PEO in water exhibit two peaks which correspond to the formation of single micelles (Rg ) 12.8 nm) and secondary micellar clusters (Rg ) 42.1 nm). Experimental data show that the weight fraction of micelles and micellar clusters in the solution strongly depends on the chemical composition of the dispersing media. The addition of 1.5 vol % toluene, which is a good solvent for the glassy polystyrene cores, decomposes the micellar clusters due to an increase of mobility of macromolecules forming micelles. Addition of inorganic salts interacting with poly(ethylene oxide) tails also results in the disappearance of micellar clusters. Alcohols introduced as cosolvents can strongly change the morphology of the amphiphilic PS-b-PEO micelles.

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The laser photolysis of gold AuIII salts embedded in micelle cores of block copolymer micelles derived from polystyrene−poly-4-vinylpyridine was studied. Two types of polystyrene−poly-4-vinylpyridines having different block length have been employed, producing micelles with different properties. The influence of the type of gold salt, loading rate, presence of water, micelle characteristics, and some other parameters on the rate of reduction and gold colloid formation were investigated. The presence of water in the system containing HAuCl4·3H2O was found to accelerate the AuIII reduction, while the gold colloid size was not affected (about 3 nm). The substitution of HAuCl4·3H2O with AuCl3 results in much slower accumulation of AuI species with subsequent slower nucleation of gold colloids that results in bigger particles with mean diameter of 6.0 nm. Increasing the amount of metal compound was found to lead to an increase of the particle size.