V. G. Sergeev

Synthesis of conducting polyaniline—polyanion interpolymer complexes and study of their composition and properties

The polymerization of aniline in the presence of poly(4-styrenesulfonic acid) and poly(2-acryla-mido-2-methyl-1-propanesulfonic acid) results in interpolyelectrolyte complexes with a composition and a dispersion stability depending on the aniline-to-polyanion ratio in the initial reaction mixture. As opposed to polymerization mediated by poly(4-styrenesulfonic acid), the template polymerization of aniline conducted in the presence of poly(2-acrylamido-2-methyl-1-propanesulfonic acid) leads to the structural template effect that manifests itself as the formation of polyaniline containing 1,2- and 1,4-substituted benzene rings. It is found that the electron conductivity of the polyaniline-polyanion interpolyelectrolyte complexes depends not only on the content but also on the nature of the used polyacid and proves to be higher in the case of stoichiometric interpolyelectrolyte complexes formed in the presence of poly(4-styrenesulfonic acid).

Rheological properties of polyacrylonitrile solutions containing highly dispersed carbon nanotubes

Rheological properties of dispersions of carbon nanotubes in dimethylsulfoxide solutions of polyacrylonitrile are studied at different concentrations of the components. The viscosity values of all the studied dispersions are substantially dependent on shear rate. For a number of systems, the energies of activation of viscous flow are determined. The relationship of viscosity and the energy of activation of flow to the compositions and possible structural features of dispersions is discussed. The concentration regime where a thermally reversible mixed network exists with crosslinks formed by physical contacts of the polymer with nano-tubes is characterized.

Molecular properties of sulfonated polyaniline

The molecular characteristics of internally doped sulfonated polyaniline with a sulfonation degree of ∼1 are studied by the methods of viscometry and dynamic light scattering. In diluted aqueous-saline solutions, the molecules of sulfonated polyaniline are individual entities; they do not form intermolecular associates and do not dissociate into separate components. An increase in the concentration of NaCl in solution from 0 to 1 mol/l brings about a sharp gain in the intrinsic viscosity of the polymer and in the hydrodynamic radius of molecules. This effect results from the decomposition of zwitterion pairs responsible for the compact conformation of polymer molecules in water. The equilibrium rigidity of sulfonated polyaniline molecules is calculated from the hydrodynamic characteristics determined in a 1 M NaCl solution, where the electrostatic interaction may be considered to be suppressed. A length of the Kuhn segment of 1.46 nm is higher by a factor of 1.5 than the corresponding length for the initial polyaniline.

Structure and Characteristics of Composite Materials Based on Polyaniline and Nylon-6

A comparative systematic study addresses the specific features of polymerization of aniline adsorbed on the Nylon matrices in the solutions containing monomer and in the monomer-free solutions. The characteristics of the formed composite materials are investigated. In the presence of aniline in the solution, a uniform and conducting composite material is obtained and its electrical conductivity reversibly depends on pH of the medium and is several orders of magnitude higher than the electrical conductivity of the composite material prepared by the polymerization of aniline in the Nylon matrix in the monomer-free solution.

Poly(N-ethyl-4-vinylpyridinium) cation-zwitterionic surfactant complexes

The interaction between poly(N-ethyl-4-vinylpyridinium bromide) and a zwitterionic surfactant has been studied in the presence of a low-molecular-mass electrolyte, sodium bromide. Both soluble and insoluble complexes have been formed. There are two essential differences between interactions of the polycation with the zwitterionic surfactant and of polycations with anionic surfacants: interaction between the polycation and the zwitterionic surfactant may proceed only in the presence of low-molecular-mass electrolytes, while interaction between the polycation and the zwitterionic surfactant in the presence of sodium bromide may take place only at surfactant concentrations above the CMC.

Synthesis and properties of latex particles with polyaniline shells

Core–shell polyaniline–latex particles have been obtained via oxidative polymerization of aniline hydrochloride in the presence of charged polystyrene latex. The polymerization conditions have been determined under which polyaniline is predominantly formed on the surface of latex particles to yield closed shells. The dependence of the electrical conductivity of the resulting particles on the initial concentration of aniline hydrochloride in the polymerization medium has been studied. Stable aqueous dispersions of polyaniline–latex particles have been prepared by modifying the particles with sodium 3-mercaptopropane sulfonate.