Membranotropic properties of fullerene-containing amphiphilic (co)polymers of <Emphasis Type="Italic">N</Emphasis>-vinylpyrrolidone

The effect of fullerene-containing amphiphilic (co)polymers of N-vinylpyrrolidone (C₆₀/PVP) differed in composition and topology of the polymer chains on the membrane structure of phosphatidylcholine liposomes was studied. Using the method of fluorescent probes it was found that the C₆₀/PVP structures under study are localized in the phosphatidylcholine membrane in the region of glycerol fragments and fatty acid chains of phospholipids. The C₆₀/PVP copolymers form complexes with 2,7-dibromoproflavin and pyrene probes. The effective equilibrium constants of the probe–C₆₀/PVP complexes in aqueous solutions and in the liposome membrane were determined. It is most likely that the fullerene-containing (co)polymers of N-vinylpyrrolidone form complexes not only with fluorescent probes but also with phospholipids of the liposome membrane, which reduces the stability of the probe–C₆₀/PVP complex.     

Extraction and preconcentration of anthocyan dye from aqueous solutions with water-soluble poly-N-vinylamides

Extraction of an anthocyan dye with poly-N-vinylpyrrolidone (PVP) and poly-N-vinylcaprolactam (PVC) under the conditions of separation of aqueous solutions of this polymer into two phases in the presence of salting-out agents (sodium chloride and sodium or ammonium sulfate) was studied.     

Thermo‐sensitive amphiphilic poly(N‐vinylcaprolactam) copolymers: synthesis and solution properties

Thermo‐sensitive amphiphilic copolymers, PVCL‐PTrpAMT and PVCL‐PVP‐PTrpAMT of hydrophilic N‐vinylcaprolactam (VCL), N‐vinylpyrrolidone (NVP), and hydrophobic N‐t‐Boc‐tryptophanamido‐N′‐methacryl thioureas (TrpAMT) monomers, were synthesized and characterized by ¹H NMR, UV‐spectroscopy, and GPC‐MALLS. The cloud point (CP) measurement showed that hydrophobic PTrpAMT and hydrophilic PVP segments significantly altered the phase transition temperature of PVCL with comparable molecular weight in aqueous solution. The CP of PVP‐PTrpAMT solution was 38.0°C, lower by 5.0°C than that of unmodified PVCL. In the presence of phosphate buffer saline (PBS), the CP value of the PVCL polymer decreased by ～2.0°C in comparison to that of the aqueous solution. Fluorescent spectroscopy and TEM studies revealed that PVCL‐PTrpAMT and PVCL‐PVP‐PTrpAMT self‐assembled into the spherical micelles, 30–70 nm in diameter, at concentrations over their CMCs in an aqueous solution. Cytotoxicity tests demonstrated that the PVCL copolymers were not harmful to cell viability, which may favor the use of the copolymers as potential thermo‐sensitive polymers in pharmaceutical applications. Copyright © 2009 John Wiley & Sons, Ltd.     

Temperature behavior of thermo-responsive poly-N-vinylcaprolactam and poly-N-isopropylmethacrylamide in aqueous solutions involving organic solutes

Poly-N-vinylcaprolactam (PVCL) and poly-N-isopropylmethacrylamide (PIMA) undergo reversible sharp phase separation in water as a function of temperature. Phase separation behaviour was studied for aqueous solutions of these polymers containing amides and alcohols as a function of solute concentration and structure. It is observed that the temperature behaviour of PIMA is not sensitive to solute structure. For PVCL, solute structure affects the phase separation temperature, and possible reasons for the experimental observations are considered.     

Copolymerization of N-vinylpyrrole-2-carbaldehydes with styrene, N-vinylpyrrolidone, and ethylene glycol vinyl glycidyl ether

Polyfunctional reactive copolymers of N-vinylpyrrole-2-carbaldehydes with styrene, N-vinylpyrrolidone, and ethylene glycol vinyl glycidyl ether are synthesized in the presence of AIBN (2 wt %, 80°C, 50 h) with a yield of up to 98% and a molecular mass of up to 4800. The copolymers show paramagnetic behavior (N = 2.0 × 10¹⁵?2.0 × 10¹⁷ g^?1) and possess the properties of organic semiconductors (σ = 0.9 × 10^?11–2.8 × 10^?7 S/cm after doping with I₂).     

Flow birefringence and optical anisotropy of poly(N-vinylpyrrolidone) molecules

Concentration dependences of flow birefringence and viscosity of poly(N-vinylpyrrolidone) solutions in water and benzyl alcohol are investigated. The intrinsic anisotropy for a poly(N-vinylpyrrolidone) macromolecular segment, (α₁ ? α₂) = ?(82 ± 8) × 10^?25 cm³, is determined from the results of birefringence measurements in benzyl alcohol. For aqueous solutions, a strong concentration dependence of the specific anisotropy of solution is obtained, a result that may be explained by the heterogeneity of coils. A model allowing for this heterogeneity is suggested. It makes it possible to fit the concentration dependence to a hyperbolic function, to separate contributions of heterogeneity anisotropy and form anisotropy to the birefringence of a solution, and to estimate the segment asymmetry parameter as p = 3.0 ± 0.5.     

Novel water-soluble fluorescent polymer containing recognition units: Synthesis and interactions with PC12 cell

New water-soluble fluorescent poly(N-vinylpyrrolidone) (PVP) containing carbonylhydrazide recognition units was synthesized by free radical polymerization of N-vinylpyrrolidone in the presence of mercaptoacetic acid as chain transfer agent and then being modified by 1-pyrenebutyric acid hydrazide. FT-IR, ¹H NMR, gel permeation chromatography-multi-angle laser light scattering and fluorescence spectroscopy were used to characterize these polymers. Results of fluorescence measurements show that these polymers have a good affinity for deoxyribonucleic acid (DNA). The interactions with PC12 cell results indicated that the polymer with suitable molecular weight could penetrate into PC12 cell and emit fluorescence. This water-soluble polymer with recognition units and high luminescence can be used as a promising fluorescent probe for measurements of biomacromolecules and cells.     

Thermal Desorption of Covalently Bound Fullerene C60 from Poly-N-vinylpyrrolidone Films

Kinetics of formation of thermolysis products in heating of thin films of poly-N-vinylpyrrolidone and of poly-N-vinylpyrrolidone with covalently bound fullerene C₆₀ was studied by thermal desorption mass spectrometry.     

Dipole Structure and Electrooptical Properties of Poly-N-vinylpyrrolydone in Nonaqueous Solvents

Electrooptical Kerr effect and dielectric polarization were studied for poly-N-vinylpyrrolidone solutions in chloroform and in mixed chloroform-CCl₄ solvent. The results were compared with those for an analogue of the monomeric unit of poly-N-vinylpyrrolidone, low-molecular-weight compound N-methylpyrrolidone.     

Zn|ZnI2| iodine secondary galvanic cells using iodine adducts of nylon-6 and other polymers as positive electrodes

Zn|ZnI₂| iodine galvanic cells using carbon plate electrodes coated with polymer + carbon powder mixtures are rechargeable with minor self-discharge when a positive ion exchanging film is used as the separator. Among the polymers tested (nylon-6, Poly(tetrahydrofuran), poly(acrylonitrile), poly(methly methacrylate), poly(vinly Alcohol), poly(N-vinylpyrrolidone), and poly(4-vinylpridine)), nylon-6 and poly(tetrahydrofuran) have the highest ability to absorb iodine and afford secondary galvanic cells showing the best rechargeability: the secondary galvanic cells are rechargeable more than 500 times with about 100% current efficiency and 81–83% energy efficiency when charged and discharged at 2 mA/cm² at 25°C. The average charging and discharging voltages of the secondary cell using nylon-6 are 1.42 and 1.18 V, respectively. The cell prepared by using nylon-6 generates about 80 mA/cm² of an initial short-circuit current and 0.3–80 mA/cm² of a steady-state short-circuit current when the cell is dipped into a aqueous solution containing I^?₃. The steady-state short-circuit current increases with increasing I^?₃ concentration and a linear correlation holds between the logarithm of the steady-state short-circuit current and the logarithm of [I^?₃] in the range of [I^?₃] = 0.05–0.5 mol/1.     

Competition between polyelectrolyte macromolecules and amphiphilic polymer micelles in interaction with copper nanoparticles

Competition between poly(1,2-dimethyl-5-vinylpyridinium methyl sulfate) polycationic macromolecules and micelles of amphiphilic polymers containing hydrophilic and hydrophobic blocks (polyethylene glycol-600 monolaurate and poly-N-vinylpyrrolidone monostearate) for copper nanoparticles was studied by means of electrophoresis and electron microscopy techniques. It was shown that, irrespective of the formation method, almost all copper nanoparticles were bonded to the polycation in polycation-polyethylene glycol-600 monolaurate mixed solutions but were distributed between the polymers in polycation-poly-N-vinylpyrrolidone monostearate mixtures. It was concluded that the stability of the complex of copper nanoparticles with the polycation is higher than that with polyethylene glycol-600 monolaurate and is comparable with that of the copper particle-poly-N-vinylpyrrolidone monostearate complex.     

Complexation in Water-Soluble Systems Poly-N-vinylpyrrolidone-Fullerene C60

Complexes of fullerene C_{6 0} with poly-N-vinylpyrrolidone were prepared by various procedures in the presence of additional agents in solution (systems C_{6 0}-poly-N-vinylpyrrolidone and ternary system C_{6 0}-tetraphenylporphyrin-poly-N-vinylpyrrolidone) and in the solid phase (C_{6 0}-polyvinylpyrrolidone and C_{6 0}-KBr-poly-N-vinylpyrrolidone). Formation of a donor-acceptor bond in the system C_{6 0}-poly-N-vinylpyrrolidone was studied by ¹³C NMR. The conditions under which the ternary complex C_{6 0}-tetraphenylporphyrin-poly-N-vinylpyrrolidone with fullerene content varied from 1 to 5 wt % can be obtained were found.     

Organic-inorganic hybrid hydrogels based on linear poly(N-vinylpyrrolidone) and products of hydrolytic polycondensation of tetramethoxysilane

The initial stage of gelation of organic-inorganic hybrid hydrogels based on poly(N-vinylpyrrolidone) and the products of hydrolytic polycondensation of tetramethoxysilane has been studied by capillary viscometry. The development of strong bonds between polymer molecules and silica particles in aqueous solutions is proved by the electrokinetic sonic amplitude method. The molecular mass of poly(N-vinylpyrrolidone), the concentration of starting components, and their total amount affect the onset time of gelation in poly(N-vinylpyrrolidone)—water—tetramethoxysilane systems. The general scheme of formation of three-dimensional networks in such systems under the conditions of mutual penetration of poly(N-vinylpyrrolidone) coils is suggested. According to this scheme, nanoparticles of the general formula SiO _x (OH) _y (OR) _z linking poly(N-vinylpyrrolidone) macromolecules serve as junctions of the gel network due to the formation of hydrogen bonds between hydrogens of silanol groups of organosilanes and oxygens of carbonyl groups of poly(N-vinylpyrrolidone).     

Water-soluble complexes of poly(N-vinylamides) of various structures with C60 and C70 fullerenes

By the example of the interaction of fullerene C₆₀ and poly(N-vinylpyrrolidone), the effect of formation conditions of water-soluble fullerene-containing donor-acceptor polymer systems on their composition and structure has been studied. On the basis of these results, a new technique has been developed for preparing water-soluble polymer systems of this kind with the use of o-dichlorobenzene as a component of the reaction medium. This technique has been employed to prepare water-soluble fullerene-containing complexes of poly(N-vinylamides) of various structures (polymers and copolymers of N-vinylpyrrolidone and N-vinylcaprolactam) containing up to 3–5 wt % of C₆₀ and C₇₀ fullerenes. These values are 3–6 times higher than those described previously.     

Adsorption of Cl−, Br−, and I− ions from 0.1 M solutions in methanol on Ga, (In-Ga), and (Tl-Ga) electrodes

Adsorption of Cl^?, Br^?, and I^? (Hal^?) ions from 0.1 M solutions in methanol (MeOH) is studied on the liquid renewable Ga, (In-Ga), and (Tl-Ga) electrodes by the methods of differential capacitance and jet electrode. It is shown that the adsorption parameters and the series of surface activity of halide ions in MeOH essentially depend on the metal nature. On the (In-Ga) and (Tl-Ga) electrodes, as well as on the Hg electrode, the surface activity of halide ions increases in the series: Cl^? < Br^? < I^?; on the Ga electrode, it varies in another series: Br^? < Cl^? < I^?. The data for the Ga/MeOH interface support the result, which was first obtained on the Ga/N-methyl formamide (N-MF) interface, that the effect of inversion of surface activity series can be observed not only in the aprotic solvents, but also in the protic solvents. The data, which were obtained in MeOH, are compared with the corresponding data, which were obtained in N-MF, dimethyl formamide (DMF), acetonitrile (AN), and water. For Ga, (In-Ga), and (Tl-Ga) electrodes, the adsorption of Hal^? varies in the series: H₂O < MeOH ≈ N-MF < DMF < AN. The data obtained in MeOH indicate that the energy of metal-Hal^? interaction (ΔG _M-Hal) increases in the series (Tl-Ga) < (In-Ga) < Ga as the electronic work function increases. This is in agreement with the data, which were obtained in other solvents, and is the evidence for the donor-acceptor nature of metal-Hal^? interaction, where the Hal^? ions are the donors of electron pair with respect to the metal.     

Chlorination of N-Methylacetamide: A kinetic study

In the pH range 4.3–13, the reaction between N-methylacetamide (NMA) and sodium hypochlorite in dilute aqueous solution to give N-chloro-N-methylacetamide (CINMA) was found to be far slower than analogous reactions affording N-chloramines or N-chloroamino acids. The rate expression for chlorination was first-order each in [NMA] and [Cl_tot] (the total concentration of chlorinating species). A rate constant calculated for chlorination by each chlorinating species indicated that the order of increasing reactivity was HClO < ClO^? < Cl₂ < CH₃COOCl (formed in the presence of acetic/acetate buffer). At pH > 7 the reaction rate was unaffected by variations in [Cl^?] or pH, but under acidic conditions the rate increased with [Cl^?] and decreasing pH. Regardless of pH, the reaction rate was not affected by changes in ionic strength. The influence of temperature on the reaction rate was also studied which allowed calculation of thermodynamic activation parameters for the N-chlorination reaction. © 1995 John Wiley & Sons, Inc.     

Kinetics and mechanism of some fast anation reactions of a series of substituted dien complexes of palladium(II). Temperature and pressure dependencies in weakly acidic aqueous solution1

Anation reactions of the type [Pd(L)(H₂O)]²⁺ + X^? »[Pd(L)X]⁺ + H₂O with L = 1, 4, 7-Et₃dien, 1, 1, 7, 7-Me₄dien and 1, 1, 4, 7, 7-Me₅dien and X^? = Cl^?, Br^?, I^? and N₃? have been studied kinetically as a function of [X?], temperature and pressure (up to 1 kbar). Second-order anation rate constants decrease with an increase in the size of L, and are accompanied by an increase in ΔH≠. For a given L the sequence Cl^? < Br^? < I^? < N₃^? holds, and the values of ΔS≠ and ΔV≠ are consistent with an associative mechanism. The results are discussed with reference to similar anation reactions previously investigated.     

Postradiation copolymerization of N-vinylpyrrolidone with triethylene glycol dimethacrylate

The kinetics of low-temperature postradiation copolymerization of N-vinylpyrrolidone (N-VP) with triethylene glycol dimethacrylate (TGM-3) were studied using reactant mixtures with different compositions and different pre-irradiation doses, and the characteristics of the obtained copolymers were determined. The copolymerization process is most effective in glassy systems (at an N-VP concentration in solution below 80 mol %). It was shown that a poly-N-vinylpyrrolidone homopolymer is formed along with a crosslinked N-VP-TGM-3 copolymer.     

Coordination d'anions organophosphores: 2eme partie. Perturbations provoquées par les coordinats “halogéno” et “pseudohalogeno” dans des complexes du zinc(II). Étude par spectro

Infrared and nuclear magnetic resonance spectroscopy data are presented for a series of complexes [ZnXL], where L^? denotes the {(C₂H₅O)₂POCHCOCH₂NR₂}^? anion with R = CH₃ (La^?) or C₂H₅ (Lb^?) and X a halogen or pseudohalogen. The infrared data reveal that the splitting of the absorption v(P → O) depends on the nature of X^? and is interpreted in terms of a crystal effect. The following order Cl^? < NCO^? ~ Br^? < I^? < NCS^? < NCSe^? is consistent with the ligand size. Nonequivalent protons on a given methylene group and nonequivalent methyl or ethyl groups bonded to nitrogen are detected by NMR spectroscopy of deuterochloroform solutions of these complexes. With La^?, the rate of exchange increases in the order NCO^?, Cl^?, Br^?, X^? (X^? = I^?, NCS^?, NCSe^?). The kinetic parameters for exchange of nonequivalent N(CH₃)₂ groups were determined.     

Preparation and Properties of Blends of Ion-Containing Polyurethane with Polyvinylpyrrolidone

Binary blends of linear polymers, segmented polyurethane [derived from oligooxytetramethylene glycol (MW 1000), toluene diisocyanate (65 : 35 isomer mixture), and magnesium p-hydroxybenzoate] and poly-N-vinylpyrrolidone (MW 10000), were prepared and studied.