Anatolii D. Pomogailo

SYNTHESIS AND REACTIVITY OF METAL-CONTAINING MONOMERS. 47. SYNTHESIS AND STRUCTURE OF SALTS OF UNSATURATED DICARBOXYLIC ACIDS

Acid and neutral CoII, CuII, NiII, ZnII, FeII, and FeIII maleates, fumarates, and itaconates were obtained and characterized. The methods for their synthesis were optimized, and the valence state and coordination of metals were studied. CoII and FeII hydrogen maleates, CoII maleate, and CoII fumarate were examined by X-ray diffraction analysis. The ligands based on unsaturated dicarboxylic acids can be mono-, bi-, and tetradentate, which results in the formation of acid salts, chain and three-dimensional coordination polymers, whose double bond is not involved in the coordination. The strong antiferromagnetic exchange (μelf=1.41 and 0.34 μB at 290 and 80 K, respectively) was detected in CuII itaconate. Based on the data of Mössbauer spectroscopy, the partial reduction of FeIII to FeII during the synthesis of FeIII maleate was shown to occur: δFe=0.43 and 1.27 mm s−1, ΔEQ=0.57 and 3.13 mm s−1 and Γ=0.37 and 0.28 mm s−1 atT=298 K for FeIII and FeII, respectively.

Synthesis and structure of vinylporphyrin metal complexes and their copolymerization. Spectral luminescence properties of Zn copolymers in solution

Vinylporphyrins containing one vinyl group at the pyrrole or benzene ring and their complexes with Cu2+ and Zn2+ have been obtained by the Wittig reaction. The compounds obtained were characterized by physicochemical methods. X-ray diffraction analysis of 5-(4-vinylphenyl)-10,15,20-triphenylporphyrin has been carried out. It is likely that the inclusion of the vinyl group is accompanied by weak electron effects on the macrocycles. The radical-induced copolymerization of meso-tetraphenylporphyrin monomers with the vinyl group in a benzene or pyrrole ring and their copper and zinc complexes with styrene and methacrylate was studied. Porphyrin comonomers decrease the overall polymerization rate and the number-average molecular weight of the products formed compared with the weight of polystyrene obtained under similar conditions. The main reasons for termination of chain growth by vinylporphyrins were revealed and some quantitative parameters of these reactions were obtained. IR and electronic absorption spectra of porphyrin-containing copolymers are discussed. According to the ESR spectra, the copper-containing centres in the copolymers are fairly remote from each other, and the metal-containing polymeric systems are magnetically dilute. The spectral luminescence properties of solutions of zinc 5-(4-vinylphenyl)-10,15,20-triphenylporphyrin–methyl methacrylate copolymers with various contents of porphyrin groups were studied. It was shown that a new long-wave band appears in the absorption spectra of the copolymers, the intensity of which depends on the copolymer composition, and the quantum yield of fluorescence decreases with increasing molar fraction of porphyrin groups.

The autowave modes of solid phase polymerization of metal-containing monomers in two- and three-dimensional fiberglass-filled matrices

The phenomenon of autowave (frontal) solid phase polymerization of metal-containing monomers based on metal-acrylamide complexes is considered. The comparison of the features of autowave processes realized in both the single-component matrices of the monomer and the matrices filled by the fiberglass materials is performed. The unstable regimes of the polymerization wave as well as the conditions for the stabilization of the flat front in the filled matrices are described. The peculiarities of the frontal regimes in the three- and two-dimensional media are studied. Some possibilities for using of autowave polymerization in the fabrication of the polymer-fiberglass composites and composition prepregs are discussed. (c) 1999 American Institute of Physics.

Frontal Polymerization of Metal-Containing Monomers: A Topical Review

The peculiarities of the frontal polymerization of metal-containing monomers containing acrylamide (AAm) complexes of transition metal nitrates, M(AAm)x(H2O)y(NO3)2 (M=Co, Ni, Fe, Cu, Zn, Cd, Ba), that are thermally initiated at 353–433 K are considered. It was found that nitrogen oxides (e.g., NO2, NO, N2O), which were formed by partial oxidation of the nitrate groups, were able to initiate the polymerization reaction. The reaction front and a self-sustained thermal wave were determined by structural-chemical and energy factors. The application of a self-propagating frontal polymerization to synthesize metal-containing copolymers was demonstrated. The constants of reactivity of the monomers (r1=0.63, r2=0.70) confirmed the statistical character of the copolymers obtained. Frontal polymerization of the AAm complexes that were filled by silica or glass powder was studied. Adding fillers stabilized the front and resulted in spatially uniform products. By following the controlled thermolysis of the metallopolymer or the controlled change of frontal polymerization into the burning regime lead to the formation of metallopolymer nanocomposites. The products were metal (or metal oxides) nano-scale particles that were stabilized by the polymer matrix that is formed.

Reactivity of metal-containing monomers

Thermal conversion of cobalt(II) maleate, CoC4H2O42H2O, (1) at 340–370 °C was studied. The composition of the products of pyrolysis was determined. The major solid-phase product of decomposition consists of nano-sized particles of CoO (sizes vary within narrow limits) stabilized by the polymeric matrix. Thermal conversions of CoII maleate involve dehydration, polymerization of dehydrated monomers, and decarboxylation of the resulting polymer.

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.

PREPARATION AND REACTIVITY OF METAL-CONTAINING MONOMERS. 14. COMPOSITION AND STRUCTURE OF ACRYLAMIDE COMPLEXES OF TRANSITION METALS

We have obtained and characterized acrylamide complexes (AAm) of chlorides and nitrates of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), and Zn(II). We have shown that all the complexes of chlorides and also nitrates of Fe(III) and Cu(II) have the composition MXn·4AAm, while the complexes of Mn(II), Co(II), Ni(II), and Zn(II) contain water of crystallization and are characterized by the composition MXn·4AAm·2H2O. All the investigated complexes have an octahedral structure. In the example of the Co(II) nitrate complex we have established that coordination of the acrylamide occurs at the oxygen atom of the carbonyl group; in this case, the double bond is not touched. However, in the crystal we observe nonequivalence of the double bonds of the acrylamide groups.

Hafnium-containing Nanocomposites

Hafnium-containing nanocomposites are prepared using polymermediated synthesis and controlled thermolysis. The new types of Hf-containing monomers and polymers were synthesized. The composition and structure of the synthesized hafnium-containing precursors and thermolysis products are determined by elemental analysis, IR spectroscopy, mass spectrometry, optical and scanning electron microscopies, and x-ray diffraction. Thermodynamic analysis is used to assess the equilibrium composition of the Hf–C–H–O system and establish the conditions under which HfC and HfO2 are formed.

Self-Organized Metal-Polymer Nanocomposites

A new approach for obtaining matrix-stabilized nanosized particles of metals and their oxides (size less than 50 nm) which are synthesized in one stage by chemical reaction within a condensed phase are elaborated. Such processes are realized by (co)poly merization of metal- containing monomers which include a metal ion chemically bonded with an organic part of a molecule. The molecular and supramolecular organization of such nano-composites is formed in the course of controlled thermal conversion of metal-containing monomers in an inert or self- generating atmosphere. The main stages of this conversion are (a) dehydration, (b) thermal (co)polymerization including self propagation frontal polymerization, (c ) controlled pyrolysis of formed products. Variation of synthesis and pyrolysis conditions leads to formation both of nano- particles with given size and necessary particle size distri butions and of a stabilizing polymeric matrix with controlled composition and thickness.

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 Rh 6 (CO) 16 with 4-vinylpyridine (4-VPy) in the presence of trimethylamin-N-oxide. Substitution of labile acetonitrile ligand in Rh 6 (CO) 15 NCMe by allyldiphenylphosphine (AlPPh 2 ) yields Rh 6 (CO) 14 (μ,η 2 -PPh 2 CH 2 CH=CH 2 ) with formation of π-complex. The structures of Rh 6 (CO) 15 (4-VPy), Rh 6 (CO) 14 (μ,η 2 -PPh 2 CH 2 CH=CH 2 ) and (μ-H)Os 3 (μ-OCNM 2 )(CO) 9 PPH 2 CH 2 CH=CH 2 have been determined by single-crystal X-ray diffraction studies, as well as by IR-, 1 H NMR spectroscopies. The Rh - Rh bond lengths are within 2.72÷2.80 A. The copolymerization of cluster-containing monomers synthesized with traditional monomers has been studied. It was found that Rh 6 - and Os 3 -containing monomers did not change either the ligand surroundings or the structure of cluster monomer framework during polymerization reaction.