ADVANCES IN THE SYNTHESIS AND POLYMERIZATION OF METAL-CONTAINING MONOMERS

Abstract

Polymerization and copolymerization of metal-containing monomers (MCM) is a unique method of synthesizing metal-containing polymers wherein practically all functional groups are bound to the metal.     

Reactivity of metal-containing monomers 70. Preparation and magnetic properties of metal-containing nanocomposites

Nanocomposites containing magnetically active nanoparticles stabilized by the carbon-containing matrix formed in parallel were obtained by the polymerization—destruction synthesis. The composition, structure, and magnetic properties of nanocomposites synthesized by the thermal decomposition of unsaturated metal carboxylates and transition metal (Co^II, Ni^II, Fe^III) acrylamide complexes were studied by powder X-ray diffraction, scanning and transmission electron microscopy, and Mössbauer spectroscopy. The key macro stages and kinetic features of thermolysis of the metal-containing monomers were identified. The variation of the conditions of thermal transformations allows one to control the magnetic properties of nanocomposites from ferromagnetic to superparamagnetic behavior.

     

Polymerization of olefins with nonstationary catalytic systems in a stationary mode

The functioning of an ideal mixing reactor in the polymerization of olefins with nonstationary catalytic systems in a steady mode was studied. Equations are derived for the dependence of the stationary polymerization rate and the degree of polymerization of the forming polymers on the intensity of the material exchange of the reactor from the external medium, and the rate constants of the elementary reactions-initiation, growth, chain termination, and formation and deactivation of active centers.     

Polymer-modified supported palladium catalysts for the hydrogenation of acetylene compounds

Palladium catalysts supported on zinc oxide modified with polyethylene glycol or pectin were synthesized and investigated in the hydrogenation of acetylene compounds. It was established that the polymercontaining catalysts reduce acetylene hyrbons to olefins with high activity, selectivity, and stability. The composition and structure of the obtained composites were studied by elemental analysis, transmission electron microscopy, and XPS spectroscopy. It was found that the nanosized particles of palladium uniformly immobilized on the surface of zinc oxide were formed in the course of the synthesis of a supported polymer/oxide complex.     

Synthesis and properties of Rh6- and Os3-cluster-containing monomers and their copolymers with styrene

Cluster metal-containing monomers were obtained and characterized. Mono- and disubstituted products were obtained under mild conditions via the interaction of Rh₆(CO)₁₆ with 4-vinylpyridine (4-VPy) in the presence of trimethylamin-N-oxide. Substitution of labile acetonitrile ligand in Rh₆(CO)₁₅NCMe by allyldiphenylphosphine (AlPPh₂) yields Rh₆(CO)₁₄(μ,η²-PPh₂CH₂CH=CH₂) with formation of π-complex. The structures of Rh₆(CO)₁₅(4-VPy), Rh₆(CO)₁₄(μ,η²-PPh₂CH₂CH=CH₂) and (μ-H)Os₃(μ-OCNM₂)(CO)₉PPH₂CH₂CH=CH₂ have been determined by single-crystal X-ray diffraction studies, as well as by IR-, ¹H NMR spectroscopies. The Rh - Rh bond lengths are within 2.72÷2.80 Å. The copolymerization of cluster-containing monomers synthesized with traditional monomers has been studied. It was found that Rh₆- and Os₃-containing monomers did not change either the ligand surroundings or the structure of cluster monomer framework during polymerization reaction.     

(Co)polymerization of metal-containing monomers as a way of MMC synthesis

The principal advances and problems of the synthesis, of poly-, co- and graft- polymerization of metal-containing monomers (MCM) are analysed. The MCMs are classified on the type of the metal bond with the organic part of the molecule, viz. MCM with σ-, nv-, and π-bonds. The effect of a transition metal on both the polymerization and on the properties of the products formed is of special interest. The basic fields of application of metal-containing polymers have been summed up.     

Polymer composites of nano-sized particles isolated in matrix

The kinetic and mechanism of thermal decay of transition metal acrylates or its cocrystallites are studied. At 200–300°C the rate of thermal decay can be described by first-order rate equations. The thermal transformations of the metal-containing monomers under study involve dehydration, solid-phase polymerization and thermolysis processes. The composition of products of the thermal transformations are studied. The products of the decay are analyzed by optical and electron microscopy as well as by magnetic measurements, IR and mass spectroscopy. The main solid-state products of decomposition are nanometer-sized particles of metal or its oxide and ferrites with a narrow size distribution stabilized by the polymeric matrix. The average particle sizes, L_av, are 6.0–13.0 nm in the case of FeAcr₃ and 6.0 nm for cocrystallites FeCoAcr and Fe₂CoAcr. © 1998 John Wiley & Sons, Ltd.