V. S. Savost'yanov

ELECTROPHYSICAL PROPERTIES OF METAL NITRATE COMPLEXES WITH POLYACRYLAMIDE

The electrophysical characteristics of metallopolymers obtained by spontaneous polymerization of complexes of Er, Ca, and UO2 nitrates with acrylamide were investigated. The conductivity (σ) at direct current was measured (10−5 to 10−6 Ohm−1 cm−1), and its alterations during the polymerization were observed. The conductivity of the metallopolymers obtained depends essentially on the voltage applied during the polymerization and the component ratio in the original mixture. It is concluded that the conductivity is ionic in character. The conductivity and the electret properties discovered depend on the moisture content of the samples.

Preparation and reactivity of metal containing monomers 42.* Copolymerization of metal containing monomers as a route for the synthesis of the precursors of high temperature superconducting ceramics

The preparation of HTSC ceramics based on YIII and BiIII was studied. The polymers were obtained by two methods: by the reaction of preliminarily synthesized polyacrylic acid (PAA) or polyacrylamide (PAAm) with YIII, BaII, and CuII nitrates or by copolymerization of metal containing monomers (metal (YII, BaII, and CuII) acrylates or acrylamide complexes of metal (BiIII, CaII, SrII, PbII, and CuII) nitrates). The copolymerization was carried out in solution, in the solid phase, or using spontaneous polymerization, which has been previously discovered by the authors. The properties of the HTSC ceramics obtained are improved when the products of copolymerization of metal containing monomers are used.

Preparation and reactivity of metal-containing monomers: 15. Frontal polymerization of acrylamide complexes of transition metals

We have observed the phenomenon of thermally initiated frontal polymerization of acrylamide complexes of nitrates of Mn(II), Co(II), Ni(II), and Zn(II). The velocity of propagation of the polymerization front when using different complexes is (2–9)·10−2 cm/sec and decreases in the sequence of nitrates: Co(II) > Ni(II) > Mn(II) > Zn(II). Analogous complexes of Cu(II) and Fe(III) under the studied conditions are not polymerized. We have shown that the frontal polyerization products are three-dimensional polymers which are insoluble in organic solvents and slowly swell in water.

Variation of the microwave dielectric permeability of the acrylamide-calcium nitrate system during its spontaneous polymerization

The kinetics of the variation of the complex dielectric permeability at microwave frequencies of 1.1, 1.7, 2.7, and 10 GHz during spontaneous polymerization of acrylamide in the presence of the hydrate of calcium nitrate was studied. The microwave conduction of this system has an ionic nature. It was assumed that some of the water liberated during the polymerization is both transformed into a bound state and forms microinclusions of an electrolyte solution in the bulk of the polymer.

Thermal polymerization of acrylamide during the formation of the structures of acrylamide complexes with metal nitrates

The effects of the composition of MnII, CoII or NiII nitrate hydrate — acrylamide (AAM) mixtures and of the duration of their aging at ambient temperature on the structurization of acrylamide complexes and on the character of their thermal polymerization have been studied by scanning and isothermic differential calorimetry. Structurization is a rather prolonged step in the synthesis of acrylamide complexes. The peculiarities and rate of this step are determined by the composition of the mixture and by the nature of the complexforming compound; it yields several structural modifications of the AAM complexes. The thermal polymerization of those structural forms of acrylamide complexes that polymerize at low temperatures may be formally described as polymerization in an acrylamide-nitrate-water mixture. The effective activation energy of the polymerization of acrylamide mixed with MnII nitrate hydrate is 45 kJ mol−1.

Phase transitions in the product of spontaneous polymerization of the acrylamide complex of calcium nitrate

Phase transitions in the spontaneously polymerized acrylamide-calcium nitrate system have been studied by X-ray diffraction analysis. The polymerization occursvia the stage of formation of crystalline particles, which exist in a homogeneous solution and are identical to crystallites in chemical composition. At the stage of particle formation, the degree of crystallinity is 60 %, the particle size is 65 nm, and paracrystallinity is 0.0208. An amorphous metal-containing polymer is the final structural state of the system.

Kinetics of the decay of nitroxyl radicals during polymerization of a complex of acrylamide with bismuth nitrate

Kinetics of the decay of nitroxyl radicals during spontaneous polymerization of complexes of acrylamide (AAm) with BiIII nitrate has been studied by ESR. From a comparison of the experimental and calculated kinetic curves, the initiation rate constant of polymerization has been determined. The approach proposed is suitable for determining the main kinetic characteristics of other polymerizable nonparamagnetic AAm complexes with metal nitrates.

Calorimetric study of polymerizing complexes of acrylamide with cobalt(ii) nitrate

Thermal polymerization of complexes of acrylamide with CoII nitrate has been investigated by differential scanning calorimetry. The conditions of the synthesis of the samples and their treatment have been found to affect the thermal and polymerization properties of the complexes. The existence of several structural modifications of the complex differing noticeably in their polymerization ability has been revealed.

Peculiarities of the thermal polymerization of the complex-bonded acrylamide

Peculiarities of the thermal polymerization of acrylamide bonded in a complex with CoII, NiII, or CuII nitrate have been studied by differential scanning calorimetry. The polymerization can occur in the regions prior to the melting of the complex, during melting, or right after it, depending on the rate of heating and the nature of the complexing agent. The effect of the addition of water and inorganic or polymeric powders on the form and character of the polymerization thermograms, which have a complex multimodal structure in the polymerization region, has been studied. The analysis of the results obtained indicates that during heating and melting complexes of a number of structures differing in their polymerization properties are formed.

A CALORIMETRIC STUDY OF SPONTANEOUS POLYMERIZATION IN ACRYLAMIDE SYSTEMS CONTAINING METAL NITRATES

A calorimetric study of the kinetics of spontaneous polymerization of acrylamide in systems containing Cr(III) and Er(III) nitrates has been carried out. At 20–25 °C, the process is characterized by a considerable induction period (20–40 min), a fast increase of the polymerization rate, up to its maximum value (5–10 min), and its subsequent slow decrease to insignificant values. It has been established that the composition of the reaction mixture significantly affects the recorded polymerization rates, and practically does not change the time parameters and the integral degrees of conversion of the process, which are 20 and 80 % for the nitrates of Cr(III) and Er(III), respectively. The effect of the addition of water or inhibitors of radical reactions on the process has been studied.