A. S. Rozenberg

Formation, Structure and Magnetic Properties of Polymer Matrix Nanocomposites Processed by Thermal Decomposition of the Fe(III)Co(II) Acrylate Complex

Structure and magnetic properties of polymer matrix nanocomposites, processed by pyrolysis of the Fe(III)Co(II) acrylate complex, were investigated. It was shown that thermal transformation of the complex studied consisted of three macrostages: dehydration, solid state polymerisation and decarboxylation of a metallopolymer form. The main products of the decomposition were nanoparticles stabilised by polymeric matrix. The crystalline phases, which were found in the fully processed material, were Fe3O4, CoFe2O4 and CoO. The mean crystallite size was 10nm. In the intermediate stages of the thermolysis iron was present in the forms of FeIII (trivalent low – spin iron), Fe2+(divalent high – spin iron) and Fe3O4. The hysteresis loops measured at temperatures below 200K were opened and shifted towards negative field. The coercivity and remanence showed room temperature values of 0.18T and 15.5mT, respectively.

Formation of metal-containing nanoparticles in polymer matrix. Computer simulation of clusterization kinetics during the solid-phase thermal decomposition of metal-containing precursors

The scheme of computer simulation of the dynamics of the formation of metal-containing clusters in a polymer matrix during the solid-phase thermolysis of corresponding precursors is developed. The kinetics of particle nucleation and growth is studied within the framework of the model of diffusion-limited aggregation by the combined marching and Monte Carlo methods. Polymer media with different structural organization such as isotropic (globular) and anisotropic (layered and fibrillar) media are considered. Deterministic algorithms of the model are the decomposition of reactive metal-containing groups of a polymer, solid-phase diffusion of particles, and cluster dissociation. The proposed scheme makes it possible to visualize the process of cluster formation.

SYNTHESIS AND REACTIVITY OF METAL-CONTAINING MONOMERS 50. EVOLUTION OF SHORT-RANGE SURROUNDING OF FE ATOMS DURING THERMAL TRANSFORMATION OF FE3O(OOCCH =CHCOOH)6OH.3H2O

Thermal transformations of FeIII maleate, [Fe3O(OOCCH=CHCOOH)6]OH·3H2O (1), in an autogenerated atmosphere and the change in the short-range surrounding of Fe atoms during thermolysis were studied. The thermal transformations of1 are accompanied by the following processes: dehydration with simultaneous rearrangement of the ligand environment and formation of maleic acid, and polymerization of the rearranged monomer and its decarboxylation at high temperatures. In the initial stage of decarboxylation, the destruction of the metal-carboxylate Fe3O complex occurs followed by the formation of the Fe−Fe bond (r=0.246 nm). The oxidation of the Fe atoms is observed when the thermolysis duration increases.

The Study of the Mechanism of the Local Order Formation near the Iron Atoms during Thermolysis of [Fe3O(OOCCH=CHCOOH)6]OH · 3H2O as the Initial Stage of Nanoparticle Nucleation in Metal–Polymer Systems1

Rearrangement of local order near the Fe atoms was analyzed by the EXAFS spectroscopy during thermal transformation of polymerizing [Fe3O(OOCCH=CHCOOH)6]OH · 3H2O. The following processes were disclosed to be involved in the thermolysis: dehydration with simultaneous rearrangement of the ligand environment, partial removal of maleic acid molecules, and thermal polymerization of the rearranged monomer with the conserved coordination of a trinuclear Fe3O fragment with maleic ligands. The metal carboxylate [Fe3OR6] cluster decomposes without the metal–metal bonding at the initial stage of decarboxylation followed by the formation of Fe–O-containing phases. This process can be considered as the nucleation of nanoparticles in the metal–polymer system.

Burning chromium-containing compounds in the filtration combustion mode

Burning a chromium-containing compound in an air stream in the filtration combustion mode was examined. Stable combustion conditions were determined for a feed stock comprised of the chromium-containing substance and an inert material.

Mass transfer of zinc-containing compounds during filtration combustion in the counterflow regime: 3. Mass transfer at a low content of the zinc-containing component in the initial stock

The regularities of filtration combustion and of the mass transfer of zinc-containing products from model stock compositions with a low content of the zinc-containing component were experimentally studied over a range of governing parameters. The parameters of the combustion of stock samples, degree of extraction of zinc-containing products into sublimate from the condensed sample, and chemical form of the zinc-containing compounds released were determined. The results obtained were discussed.

Mass transfer of zinc-containing compounds during filtration combustion in the counterflow regime. 2. Mass transfer at a high content of zinc oxide in the stock

A thermodynamic analysis of the equilibrium composition of the gaseous and condensed products for the ZnO-C-O2-N2 system was performed. The characteristics of the filtration combustion and mass transfer of volatile products from model stocks with a high content of zinc oxide were studied. The conditions of combustion of stock samples, degree of extraction of zinc-containing products into sublimate from condensed sample, and the chemical form of zinc-containing compounds released were determined for a wide range of governing parameters.

Metal-Containing Polymers as Precursors for the Production of Ferromagnetic and Superconducting Materials

Thermal transformations of metal-containing monomers (MCM) are of interest at least for two reasons: on one hand, the study of thermal decay of MCM and their transformation products makes it possible to evaluate MCM thermal stability and its role in solid state polymerization processes. Previous studies of some metal (Zn, Co, Ni etc.) acrylate thermal decompositions, both in air and in inert atmosphere,1,2 were based on thermal analysis and provided only a qualitative picture of transformations occurring upon thermolysis. Complex kinetic studies are needed for a better understanding of these processes.