Conducting polymers demonstrate low solubility in organic solvents. Introducing aliphatic substituents into polymer chains improves their solubility, but may also lead to changes in conformational characteristics of macromolecules. In the present work, the studies of hydrodynamic properties and conformational characteristics of comb-shaped poly(3-hexylthiophene) with aliphatic side substituents were carried out in chloroform solutions. Conformational analysis of the studied macromolecules was performed for the first time using homologous series with a wide range of molecular weights of the polymers in dilute solutions. The hydrodynamic properties of these macromolecules were interpreted using the worm-like spherocylinder model and the straight spherocylinder model. The projection of the monomer unit in the direction of the main polymer chain k 5 0.37 nm was determined experimentally. The following parameters of poly(3-hexylthiophene) were characterized and quantified: equilibrium rigidity (Kuhn segment length) ff 5 6.7 nm and hydrodynamic diameter of a polymer chain d 5 0.6 nm.
The procedure of the directed synthesis of N-vinylpyrrolidone-N-vinylformamide (VP-VFA) copolymers with grafted iminodiacetate (IDA) chelating units is presented. The methods for labelling resulting conjugates with indium-113m were developed. The metal-copolymer conjugates were characterized by different physicochemical methods, including IR and NMR, viscometry, light scattering, and exclusion high-performance liquid chromatography. Parameters of radiochemical synthesis of the conjugates labelled with indium-113m were optimized. It was shown that the VP-VFA-IDA copolymer firmly binds indium-113m both in the acid and alkaline solutions, with pH of the reaction mixture having almost no effect on the complexation. VP-VFA-IDA-In conjugates were found to be unstable in histidine challenge reaction.
Copolymer of N-vinylpyrrolidone (VP) with vinylformamide (VFA) and N-vinyliminodiacetic acid (VIDA) was synthesized; its metal-polymer complexes (MPCs) with gallium were obtained. The complexes were characterized by size exclusion chromatography, hydrodynamic and optical methods, scanning electron microscopy, and spectral methods (UV, IR, 1Н NMR spectroscopy). It was demonstrated that in going from polymer to complex, hydrodynamic parameters of macromolecules change only slightly, although the polymer contains intramolecular Ga(VIDA)2 fragments in its structure. A new method for preparation of MPCs with gallium and gallium-68 radionuclide was suggested. The obtained metal-polymer complex is stable over a wide range of pH values as well as in the histidine challenge reaction. In vivo distribution experiments in intact animals showed high primary accumulation of thegallium-68 MPC in blood with subsequent excretion via urinary tract.
Poly(N,N-dimethylaminoethyl methacrylate) macromolecules in the un-ionized and ionized states were studied by methods of molecular hydrodynamics, optics, and polarized luminescence. The conformation, relaxation, and optical parameters of the macromolecules were determined. The Mark-Kuhn-Houwink equations were obtained for the intrinsic viscosity and diffusion and sedimentation coeffi cients. Poly(N,N-dimethylaminoethyl) methacrylate (PDMAEM) attracts researchers' attention for a long time. It exhibits antimicrobial and fungicidal properties; it is one of the most effective polymers for the DNA transport; it is also used as flocculant in mining industry [1][2][3][4][5][6][7]. PDMAEM is a weak base. Its temperaturesensitive properties and conformation of macromolecules are determined by the nature of the solvent (pH, ionic strength, kind of counteranions) [8][9][10][11][12][13][14]. Signifi cant role is also played by the molecular weight and architecture of PDMAEM macromolecules [12].Determination of the molecular weights and dimensions of macromolecules of amphiphilic polymers and polyelectrolytes still involves problems because of the occurrence of intra-and intermolecular interactions. This particularly concerns polyelectrolytes, because they are characterized by two oppositely acting factors: hydrophobic interaction and Coulomb repulsion. The fi rst factor leads to enhancement of intra-and intermolecular interactions which decrease the hydrodynamic volume, whereas the electrostatic forces tend to increase the volume of polymeric coils, i.e., the hydrodynamic volume. Salt additions can shield the polyelectrolytic effect but enhance the hydrophobic intramolecular interactions. Hydrophobic contacts can be broken by adding organic solvents or surfactants.In this study we determined the molecular, conformation, optical, and relaxation properties of PDMAEM in the forms of the base and salt in dilute solutions. To this end, we used the methods of molecular hydrodynamics (sedimentation, diffusion, viscometry) and optics (fl ow birefringence, polarized luminescence). EXPERIMENTAL PDMAEM was prepared by free-radical polymerization of DMAEM in benzene, toluene, or isopropanol solution at 60°С with azobis(isobutyronitrile) (AIBN) as initiator or in aqueous solution at 25°С with a 1 : 1 mixture of (NH 4 ) 2 S 2 O 8 and N,N,N',N'-tetramethylethylenediamine as initiator (Table 1).The polymer with a luminescence label was prepared by free-radical copolymerization of DMAEM with 9-anthrylmethylmethacrylamide; the concentration of the monomers in the isopropanol solution was 15 wt %, and the AIBN concentration, 1.5 wt % relative to the monomers. The content of luminescence labels in the polymer did not exceed 0.2 mol %.The intrinsic viscosities were measured by the standard procedure in the Ostwald capillary viscometer. For
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