V. D. Pautov

Pseudotemplate synthesis of copper nanoparticles in solutions of poly(acrylic acid)-pluronic blends

It was found that the reduction of copper(II) ions in solutions of poly(acrylic acid)-pluronic blends results in a stable sol of metallic copper with a particle size below 10 nm, whereas a less stable sol with coarse aggregates of particles is formed in the presence of poly(acrylic acid) alone and an insoluble complex of this polymer with copper nanoparticles is produced in the presence of pluronic alone. The addition of poly(acrylic acid) to the complex causes the transfer of a portion of nanoparticles from the precipitate into the sol. In mixed poly(acrylic acid) and pluronic solutions, no formation of a polymeric complex with reasonable stability was detected. It was assumed that such a polycomplex is stabilized in the presence of copper nanoparticles. Owing to its amphiphilic nature, the complex forms stable protective shields on the surface of nanoparticles, and the stability of the sol is determined by free fragments of poly(acrylic acid).

Structural and dynamic characteristics of a star-shaped calixarene-containing polymer in aqueous solutions: the formation of mixed-shell micelles in the presence of poly(methacrylic acid)

Structural and dynamic characteristics of a star-shaped polymer with a central tert-butylcalix[8]arene core and poly(N-isobutyryl ethylenimine)-ω-piperazine arms in aqueous solutions were studied via the polarized-luminescence method. To conduct investigations, a luminescent label of the anthracene structure was attached to the polymer. It has been shown that polymer macromolecules are in an aggregate state in water. The aggregate comprises about 5 macromolecules. During mixing of the star-shaped polymer with macromolecules of un-ionized poly(methacrylic acid), a mixed-shell micelle in which poly(methacrylic acid) units interact with both poly(N-isobutyryl ethylenimine)-ω-piperazine moieties and isobutyl fragments incorporated into the core of the micelle is formed.

Conformational and dynamic characteristics of copolymers of N,N-dimethylaminoethyl methacrylate and 2-deoxy-2-methacrylamido-D-glucose

The conformational and relaxation properties of N,N-dimethylaminoethyl methacrylate and 2-deoxy-2-methacrylamido-D-glucose copolymers in solutions are studied by the methods of molecular hydrodynamics (sedimentation, diffusion, viscometry), polarized luminescence, and flow birefringence. Kuhn-Mark-Houwink equations are obtained, and Kuhn statistical segment lengths at various degrees of protonation of amino groups are estimated. It is found that there is a correlation between the Kuhn statistical segment length and the intramolecular mobility of the copolymers.

Interpolymer complexes of poly(N-vinylpyrrolidone) with copolyimide-grafted side chains of poly(methacrylic acid)

The process of formation and structural organization of interpolymer complexes formed by macromolecules of poly(N-vinylpyrrolidone) and poly(methacrylic acid) chains grafted onto polyimide in solution is investigated via the method of polarized luminescence. A luminescent label of anthracene structure is covalently bound to both polymers. Relaxation times characterizing intramolecular mobility of each of the components in their interpolymer complex are measured in relation to the composition of the system.

Water-soluble polymer derivatives of cholesterol

New cholesterol-containing water-soluble polymers based on N-methacryloyl aminoglucose and N-vinylpyrrolidone are synthesized by free-radical copolymerization and polymer-analogous transformations. Binary and ternary copolymers of various composition containing N-allylamine and N,N,N-trimethylaminoethyl methacrylate methyl sulfate units and cholesterol residues are prepared. Luminescently labeled copolymers of the same composition are obtained. Effects of the nature of polymers and the amount of cholesterol in them on the intramolecular mobility of macromolecules in solution are studied with polarized luminescence. When 2–4 mol % of cholesterol residues are incorporated into the copolymer, the intramolecular mobility of macromolecules decreases, thus indicating formation of intramolecular compact structures via interaction of nonpolar cholesterol groups. In copolymers containing charged groups, these structures are looser than those in neutral copolymers. It is shown that macromolecules of cholesterol-containing polymers of various types can interact with each other. 1 This work was supported by the Russian Foundation for Basic Research (project no. 08-03-00324) and the Council for Grants of the President of the Russian Federation for Support of Leading Institutes of Higher Education (NSh-4391.2008.3).

Relaxation properties and complex formation of copolymers of 2-deoxy-2-methacrylamido-D-glucose and unsaturated acids

With the use of polarized luminescence, relaxation times characterizing the intramolecular mobility of luminescent labeled copolymers of 2-deoxy-2-methacrylamido-D-glucose and unsaturated acids in solutions are determined in both nonionized and ionized states. Elements of the secondary structure typical for poly(methacrylic acid) are formed in copolymers with a high content of methacrylic acid (≥50 mol %) in their nonionized state. This structure is destroyed during ionization. Equilibrium stability constants for complexes of the copolymers with cationic surfactants are determined. Quantitative characteristics of the effects of the surfactant and copolymer structures and the ionic strength of solution on complex formation are estimated.

Intramolecular mobility of side chains of poly(methacrylic acid) in regularly grafted copolyimides in solution

A “dark” copolyimide with regularly grafted side chains of polymethacrylic acid and a luminescence-labeled copolyimide containing an anthracene label covalently attached to side chains with an average polycondensation degree of the polyimide backbone of ∼16 and an average polymerization degree of side poly(methacrylic acid) chains of ∼100 are synthesized. Relaxation times τIMM characterizing the mobility of parts of side chains in solvents of different thermodynamic qualities for the backbone and side chains are determined through the polarized luminescence method. It is shown that, in a “common” solvent for the backbone and side chains, the values of τIMM are close to those characterizing the mobility of linear polymethacrylate chains. In selective solvents, changes in τIMM are related to not only changes in intramolecular interactions but also changes in the heterogeneity of the dynamic characteristics of parts of grafted chains arranged at different distances from the grafting point.

Macromolecular metal complexes with transition-metal ions: Structure of a polymer and efficiency of complexation

A quantitative method of estimating the efficiency of formation of macromolecular metal complexes of carboxyl-containing (co)polymers with transition-metal ions in dilute solutions was developed. This method is based on the luminescence quenching of luminescently labeled macromolecules by transition-metal ions. With the use of this method, the effect of the chemical (including isomeric) structure of carboxyl-containing (co)polymers and external conditions on the stability of macromolecular metal complexes based on copper, nickel, and silver ions was assessed. With consideration for the data obtained, a targeted variation in the functional characteristics of macromolecular metal complexes may be accomplished.

Copolymers of carbazole- and indolocarbazole-containing phenylquinolines as new materials for electroluminescent devices

The photophysical and electrical properties of copolymers based on 2,6-polyphenylquinolines containing a bridging oxygen or phenylamine group between quinoline rings and octyl- or dodecylcarbazole or dioctylindolo[3,2-b]carbazole fragments in the aromatic radical are studied. It is shown that the introduction of carbazole and indolo[3,2-b]carbazole fragments emitting in the visible spectral range into the aromatic radical of a copolymer makes it possible to obtain white luminescence. The intensity of this luminescence exceeds, for copolymers in a photoinert matrix, that of the initial homopolymers. This circumstance, combined with rather high carrier mobilities on the order of 5 × 10−6 cm2 V−1 s−1, makes the copolymers promising for the development of electroluminescent devices on their basis.

Composites based on Gluconacetobacter xylinus bacterial cellulose and calcium phosphates and their dielectric properties

Dielectric properties a Gluconacetobacter xylinus bacterial cellulose and its composites with calcium phosphates were studied and used to analyze structural changes in a matrix polymer upon its mechanical treatment and introduction of a mineral fi ller. It was found that, when composites are formed, the ratio between amorphous and crystalline regions is disturbed in the cellulose matrix.