S. Zh. Ozkan

Oxidative polymerization of diphenylamine: A mechanistic study

The mechanism of oxidative polymerization of diphenylamine is considered. The kinetic study of diphenylamine polymerization and of the structure and molecular-mass characteristics of the reaction products has shown that the degree of oxidation of intermediates plays the key role in polyrecombination. The relationship between the polymerization procedure and the molecular mass of polydiphenylamine was revealed.

Oxidative Polymerization of Diphenylamine: Synthesis and Structure of Polymers

Three procedures for the chemical oxidative polymerization of diphenylamine, namely, in solutions of sulfuric acid, in an H2SO4-tert-butanol mixture, and via the interfacial process, are considered. It was shown that the highest molecular mass products are formed by the interfacial process. Oxidative hydrolysis and chain termination reactions predominate in a homogeneous medium. The effects of polymerization conditions, such as the concentration of reagents, their ratio, and the reaction temperature, on the yield and molecular-mass characteristics of polydiphenylamine were studied. The structure of reaction products was investigated by UV spectroscopy. It was demonstrated that, even when ammonium persulfate is in excess, the degree of oxidation of polydiphenylamine is rather small and chain propagation proceeds as a C-C rather than N-C addition as in the case of aniline.

Thermal stability of polydiphenylamine synthesized through oxidative polymerization of diphenylamine

The thermal stability of polydiphenylamine synthesized through the oxidative polymerization of diphenylamine has been studied. It has been established that the main processes of thermal and thermooxidative degradation of polydiphenylamine begin at 600–650 and 450°C, respectively. It has been shown that, in the course of thermal oxidation of the doped polydiphenylamine, the elimination of a dopant takes place first. With a further increase in temperature, the behavior of this material becomes similar to that of the neutral polymer.

New approaches to synthesizing electroactive polymers

The chemical oxidative polymerization of aniline in a heterophase system is studied. In the presence of a solid substrate, the aniline polymerization involves two kinetically and chemically independent processes, namely, the polymerization in the bulk solution and at the substrate surface. The growth of the polyaniline coating at the substrate surface includes three successive processes: interfacial polymerization, adsorptive polymerization, and destruction of the polymer chain. The interfacial oxidative polymerization of diphenylamine and phenothiazine is examined. The yield and chemical structure of polymers is shown to depend on the polymerization conditions.

Oxidative polymerization of diphenylamine-2-carboxylic acid: Synthesis, structure, and properties of polymers

Polymers of diphenylamine-2-carboxylic acid are synthesized for the first time via chemical oxidative polymerization. The effects of the concentration of reagents, their ratio, and the temperature and time of reaction on the yield and chemical structure of poly(diphenylamine-2-carboxylic acid) are studied by IR and UV spectroscopy. It is shown that the growth of polymer chains proceeds through the C-C addition in the para position of phenyl rings relative to nitrogen. During the thermal oxidation of poly(diphenylamine-2-carboxylic acid), COOH groups and dopant molecules are successively eliminated; with a further increase in temperature, the polymer behaves as polydiphenylamine. The main processes of thermooxidative degradation of poly(diphenylamine-2-carboxylic acid) begin at 570°C. This value is 120°C higher than the corresponding parameter in the case of polydiphenylamine.

Interfacial oxidative polymerization of phenothiazine

Phenothiazine polymers have been prepared for the first time by interfacial oxidative polymerization. Effects of the concentration and ratio of reagents, temperature, and time of reaction on the yield and molecular mass characteristics of polyphenothiazine are investigated. The study of phenothiazine oxidation indicates that high-molecular-mass products can be prepared if this reaction is carried out in the absence of acids, in contrast to the classical oxidative polymerization of aniline. It is shown that phenothiazine polymers are characterized by a low oxidation state. IR spectroscopy is employed to investigate the chemical structure of the polymers as depending on the synthesis conditions. The propagation of polyphenothiazine chains occurs via the C-C addition in para positions of phenyl rings relative to nitrogen.

Metal-Polymer Nanocomposites Based on Polydiphenylamine and Cobalt Nanoparticles

It is shown for the first time that the infrared heating of polydiphenylamine in the presence of cobalt (II) acetate Co(CH3CO2)2 · 4H2O in an inert atmosphere at a sample temperature of T = 250−600°C leads to the formation of a metal-polymer nanocomposite in which Co nanoparticles are dispersed in a polymer matrix at the expense of condensation of diphenylamine crystalline oligomers with hydrogen release, promoting the reduction of Co2+ to Co0. The formation of Co nanoparticles is confirmed by X-ray phase analysis. According to data from transmission electron microscopy, Co nanoparticles have sizes of 2 < d < 8 nm. The investigation into the magnetic and thermal properties of Co/polydiphenylamine nanocomposite has shown that the nanocomposite obtained is superparamegnetic and thermostable.

Synthesis, structure, and properties of new Cu/polydiphenylamine metallopolymer nanocomposites

It was found that the Cu-induced thermal polycondensation of diphenylamine oligomers resulted in the formation of new Cu/polydiphenylamine nanocomposites composed of copper nanoparticles (2 < d < 6 nm) scattered within the polymeric matrix according to the results of an XRD analysis and transmission electron microscopy. Studies of the thermal stability of metallopolymeric materials in a nitrogen atmosphere revealed the start of the thermooxidative destruction stage at 370°C and the following gradual weight loss (up to 20 wt %) through heat treatment up to 820°C.

Polymers of diphenylamine-2-carboxylic acid: Synthesis, structure, and properties

Polymers of diphenylamine-2-carboxylic acid are prepared by chemical oxidative polymerization in an aqueous solution of ammonium hydroxide. In accordance with the IR data, during the polymerization of diphenylamine-2-carboxylic acid in a solution of ammonium hydroxide, polymer-chain growth occurs via C-C joining into 2 and 4 positions of phenyl rings with respect to nitrogen. The distinctive feature of the polymer is the absence of quinodiimine units in its structure, even if the oxidizer is in excess. The resulting polymers are amorphous, electroactive, and thermally stable.

A magnetic metal/polymer nanocomposite material based on poly(diphenylamine) and Fe3O4 nanoparticles

It was discovered that IR heating of poly(diphenylamine) in the presence of FeCl3•6H2O in an inert atmosphere at 300–700 °C produces a metal polymer nanocomposite with Fe3O4 nanoparticles dispersed in polymer matrix. This is achieved by condensation of crystalline diphenylamine oligomers with evolution of hydrogen that promotes iron reduction. The formation of Fe3O4 nanoparticles was confirmed by X-ray powder diffraction. The magnetic and thermal properties of the Fe3O4—poly(diphenylamine) nanocomposite were examined. This nanocomposite material shows superparamagnetism and thermal stability.