Polymer-immobilized nanoparticles

B. Preparation of Polymer-Immobilized Nanoparticles by Plasma Polymerization... 

D. Synthesis of Polymer-Immobilized Nanoparticles by Reductive Methods... 

E. Electrochemical Methods for Preparing Polymer-Immobilized Nanoparticles... 

Control of the evaporation conditions also allows the preparation of polymer-immobilized nanoparticles. For example, colloidal silver was obtained with the particle size of 1.0-20 nm (the colloidal Ag particles less than 40 nm in diameter absorb light at -400 nm). The dispersion of gold nanoparticles (mean particle size 2nm) in poly(diphenylbutadiyne) has been obtained by cocondensation of vapor of Au and diacetylene on a support at 77K. ... 

Reduction is the most common technique to prepare polymer-immobilized nanoparticles. Two different types of reduction can be considered. The first type, or the impregnation method, consists of the chemical reduction of metals from solutions or suspensions of their salts. Ammoniacal solutions of Cu, Cr, and Ag hydroxides are often used. Electrochemical or radiation-induced reduction in the presence of macroligands have also been employed. The reduction of mononuclear metal complexes chemically bound with polymers represent the second type. The impregnation method is more widely applied because it better meets the needs of catalysis. In particular, metal blacks, ultradispersed powders, etc. are prepared. For example, Raney nickel is stabilized by incorporating it into the silicone rubber "" followed by vulcanization at room temperature. 

The electrochemical and electroflotation methods are widely used to prepare of chemisorbed macromolecules bound to colloidal metal particles generated in situ. Electrochemical polymerization reactions are heterogeneous They are initiated on the electrode surface, while other stages (chain growth or termination) occm, as a rule, in the liquid phase. The yield of a polymer depends on the chemical and physical nature of the electrodes and their surface, electrode overvoltage, potential rmder which the reaction occurs, and electrical current density. The nature of the electrode material (metals or alloys, thin metallic coats, etc.) determines the characteristics of electron-transfer initiation and polymerization. Direct electron transfer between the electrode and monomer, cathodic deposition, and anodic solubilization of metals are optimum for electrochemical polymerization. Metal salts are the precursors of nanoparticles, which may act as specific electrochemical activators. Nanoparticles can influence activations through direct chemical binding to the monomer and by virtue of transfer, decomposition, or catalytic effects. Nonetheless, electrochemical polymerization has found only limited use in the preparation of polymer-immobilized nanoparticles. 

Not all of the approaches discussed in this section are equally developed. The priority is given to the reduction techniques. The role of the dispersive phase is mostly played by carbon-chain polymers and less often, by condensation-type polymers. The immobilization of nanoparticles is nearly always accompanied by chemical interactions of the particles formed with the matrix, in contrast to mechanical mixtures of metals with polymers. Further developments in the preparation of polymer-immobilized nanoparticles have been documented. 

C. Polymer-Immobilized Nanoparticles as Optical Materials and Semicondnctors... 

D. Catalysis Using Polymer-Immobilized Nanoparticles and Clnsters... 

---