Polymer-fine metal particles

Stabilizers are usually used during the reduction of metal ions to stabilize the colloidal dispersions of fine metal particles. The coordination interaction is the main factor to stabilize the metal particles. Thus, polymers with coordinating groups are good stabilizers. The choice of coordinating groups should depend on the kind of metal. 

Relaxational and Interfacial Properties of Fine Metal Particles-Polymer Composites... 

We found a new phenomenon In which the metal was uniformly dispersed Into the polymer in the form of line particles having diameters between 1-10 nm only by the heat treatment just above cryslallizalion temperature of the polymer. We named this new dispersion process the reiaxative auio-dispersion (RAO) process The melat-polymer composile prepared by the RAD process had various kinds of colors and interesting elecirical properties caused by the size effect of the meiat and the Interaction between the metal particles and the polymer matrix, in this paper, we will report reiaxative and Inierlacial properties of fine metal particle-polymer composites (MPPC Metal Powder-Polymer Composile) prepared by the RAD process. 

In contrast, colloid chemistry has provided the colloidal dispersion of metal fine particles in water.As early as the 1950 s, colloidal dispersion of fine particles of precious metals was conducted and applied to catalyses. Although they contain fine metal particles, the size of the particles was not so uniform. In addition they were not very stable when used in solution. Thus, there still remained many problems in the reproducibility of the preparation and catalysis using metal nanoparticles. In 1976, the author s group prepared colloidal dispersions of rhodium particles protected by water-soluble polymers by reduction of rhodium(III) ions under mild conditions, i.e., reduction with refluxing alcohol in the presence of water-soluble polymers. They were applied to the catalyst for hydrogenation of olefins. In 1989, we developed colloidal dispersions of Pd/Pt bimetallic nanoclusters by the simultaneous reduction of Pd and Pt ions in the presence of poly(A-vinyl-2-pyrrolidone) (PVP). 

The synthesis of polymer/inorganic compound nanocomposites, accomplished by multistep reactions in solutions, has been bothered by the serious problem of coagulating inorganic particles, espedaUy, fine metal particles in the polymer matrices [78-81]. In order to prevent coagulation, El-Shall and coworkers utilized... 

The polymer/metal particle composites have been synthesized by utilizing fine metal surfaces as effective initiation sites for radical polymerization of vaporized vinyl monomers. On the metal surfaces, GASP of vinyl monomers is initiated and induces the formation of polymer thin-film coatings of the fine metal particles. Andou et al. demonstrated that GASP of MMA on a zero-valent iron (Fe(0))... 

Hifumi et al. [34] applied ultra-fine platinum particles protected by poly(Me acrylate-co-N-vinyl-2-pyrrolidone) to inununological detection of metham-phetamine (MA). The polymer-protected ultra-fine particles chemically boimd anti-methamphetamine monoclonal antibody to their surfaces. The antibody-fixed particles behaved like an antibody in the inununoreaction, making it possible to detect the MA to a concentration of ca. 10 ng/mL. Uda et al described a similar application of polymer-protected ultra-fine platinum particles to the im-mvmological detection of human serum albumin [35]. Tamai et al. [36] showed that ultra-fine metal particles could be immobilized on fine copolymer particles that were produced by reducing copolymer particles-metal ion complexes. Transmission electron microscopy and X-ray diffraction were used to confirm that ultra-fine noble metal particles with a diameter below 10 run were formed and uniformly immobilized on the surface of copolymer particles. 

Chen et al. [37] studied a series of complexes of styrene-4-vinylpyridine copolymers or poly(4-vinylpyridine) and transition metal chlorides. The transition metal-polymer complexes were used to prepare ultra-fine metallic particles dispersed in a polymer matrix by chemical reduction. Upon reduction, the metal ions were transformed into the corresponding nanometer scale metal particles with the protective polymers preventing the metal particles from oxidation and excessive aggregation. Ohtaki et al. reported the effects of polymer support on the substrate selectivity of covalently immobilized ultra-fine rhodium particles as a catalyst for olefin hydrogenation [38]. 

Rotational Molding. Large containers and some toys are manufactured with a specialized technique caHed rotational mol ding. A rotational mol ding machine contains several large metal molds that can be rotated in two perpendicular planes. A load of fine LLDPE particles is introduced into each mold, and the mold assembly is transferred into an oven. Inside the oven, heated molds rotate at speeds ranging from 10 to 40 rpm. The polymer powder melts and is uniformly distributed on the internal surface of each mold. After the container is formed, the mold assembly is removed from the oven and cooled at which point the plastic containers are removed. 

These replaceable cartridges or packs are the most commonly used however, there are cartridges of wire mesh, sintered or porous metal which can be removed, cleaned, and replaced. Usually, the fine pores of the metal become progressively plugged and the cartridges lose capacity. They are often used for filtering hot fluids, or polymers with suspended particles, pharmaceuticals, and foods (liquids). In the case of polymers and other applications a special solvent and blow-back cleaning system may be employed. 

Both polymers 10 and 11 are soluble in common organic solvents, melt without decomposition, and can be drawn into the fibers. Molecular weights of the polymers 10 and 11, determined by gel permeation chromatography with tetrahydrofuran as the eluant after purification by reprecipitation from benzene-ethanol, showed a broad monomodal molecular weight distribution. The degree of polymerization depends on particle size of sodium metal. Polymers with molecular weights of 23,000-34,000 are always obtained, if fine sodium particles are used. 

It is interesting to include in this eategory of interphase systems, the use of highly water-soluble proteetive agents, like polymers, surfactants, or ionic species, to stabilize colloidal metallic particles finely dispersed in water. Larpent and Patin have developed this original approach [72]. Ruthenium eolloids ean efficiently catalyze the oxidation, under room eonditions, of cyclo-octane by t-butylhydroperoxide [73]. Recent results show that... 

Microcomposites (10 m) Composites using micron size fibers with high aspect ratio or fine hollow spheres or fibers as reinforcement are called microcomposites. The matrix can be any polymer. The reinforcing phase will be a continuous fiber or short fiber or micron sized fillers such as metal particles. The main advantage of using fibers is to improve strength, stiffness, and thermal stability of composites. 

The local field effects for composite materials require more detailed analysis and can lead to a significant enhancement of the NLO response. For example, a promising method for enhancing the nonlinearity by several orders of magnitude through local field effects is to embed either finely distributed or fractal clusters of metal particles (79) in a polymer matrix. 

Complexation of the metal by the macromolecule produces very fine metal or metal oxide particles. However, the number of metal-containing polymers which can be prepared in this way is extremely limited. 

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