Poly N-vinylpyrrolidone Research Articles

Interpolymer complexes of acrylic acid and vinylbutyl ether copolymers with non-ionic and cationic polymers

Copolymers of acrylic acid and vinylbutyl ether AA/VBE) have been involved in complexation reactions with non-ionic poly-N-vinylpyrrolidone (PVP), polyethylene glycol (PEG) and cationic poly-N-methyl-4-vinylethynylpiperidinol-4 (PVEP) and polyvinyl ether of monoethanolamine (PVEMEA) polymers. Interpolymer complexes (IPC) are stabilized due to the formation of either cooperative system of hydrogen or ionic bonds depending on the nature of interacting macromolecular components. The stoichiometry of IPC was determined by electrochemical methods. The stability of IPC depends on thermodynamic quality of the solvents, temperature, and degree of ionization. The permeability of IPC membranes with respect to urea was studied. Copyright © 2000 John Wiley & Sons, Ltd.

Preparation of monodisperse polystyrene spheres incorporating polyimide prepolymer by dispersion polymerization in the presence ofL-ascorbic acid

Addition of a small amount of L-ascorbic acid (AA) unexpectedly provided uniform-sized polystyrene (PS) spheres in an ordinary dispersion polymerization pro- cess. PS spheres incorporated with polyimide prepolymer (BANI-M), designed as possi- ble spacers for liquid crystal displays, were prepared from formulations containing a mixed solvent of isopropanol/2-methoxyethanol, 2,2*-azobisisobutyronitrile, and poly- N-vinylpyrrolidone (PVP) at 343 K. The average particle size decreased by the addition of AA; however, dramatic improvements of monodispersity were observed with various formulations. The best coefficient of variation was 1.37%, compared to 7.03% obtained without the presence of AA. Addition of AA was originally intended to scavenge a trace amount of oxygen remaining in the reactor system, promoting a rapid and short particle nucleation period, and thereby resulting in improved monodispersity. However, there was no difference in the initial reaction rate between the runs with and without AA; no noticeable induction period was observed even without AA provided that an ordinary procedure was employed to eliminate the dissolved oxygen through a nitrogen bubbling, and the nitrogen atmosphere was maintained during the reaction. It was proposed from 1 H-NMR analysis that the abstraction of hydrogen atom from the PVP chain by the oxidized form of AA promoted the formation of graft copolymer PVP-PS, which stabilizes precipitating chains in the nucleation period. Approximately 40% of BANI-M present initially was incorporated in the PS particles, which occupied 4-9% of the weight of polymer particles, well below the target value of 20%. q 1998 John Wiley &

Quick identification of polymeric dye transfer inhibitors in laundry detergents by pyrolysis-gas chromatography/mass spectrometry

This report summarizes method development for the simultaneous identification of dye transfer inhibitors (DTIs) using pyrolysis-gas chromatography with mass detection (Py-GC/MS). Ground detergent products are directly pyrolyzed and pyrolysis fragments introduced into a GC column. Key fragments separated via GC are detected by selected ion monitoring (SIM) to achieve the high sensitivity and selectivity necessary to measure markers of DTIs in the presence of high levels of surfactant by products. Trace levels of DTIs, poly- N-vinylpyrrolidone (PVP), copolymer of N-vinylpyrrolidone and N-vinylimidazole (PVPVI), and poly-4-vinylpyridine- N-oxide (PVNO) in laundry detergent products were quickly identified. Detection limits were 0.05% for PVP and 0.1% for PVPVI and PVNO.

Use of Isothermal Titration Microcalorimetry To Monitor the Adsorption/Desorption Processes of Sodium Dodecyl Sulfate with Neutral Polymers

The optimization of neutral polymer/anionic surfactant mixtures is a critical process in the development of such systems for many various applications. In this report, we describe how systematic isothermal titration microcalorimetry experiments may be designed in such a way that both the adsorption and desorption processes of sodium dodecyl sulfate with two neutral polymers, PAPR* (a copolymer of N-(vinylacryloyl)pyrrolidine containing a covalently bonded 4-vinylpyridine dicyanomethylide chromophore) and PVP (poly(N-vinylpyrrolidone)), can be directly monitored. The desorption of bound SDS from the polymers is achieved using the nonionic surfactant hexaethylene glycol mono-n-dodecyl ether and the possible mechanism via which this process takes place is qualitatively discussed. Finally, one of the beneficial outcomes stemming from this work is that different stable combinations of polymer or polymer/surfactant complex with mixed micelles and monomer surfactant can be formulated.

Molecular composites of polyimide/poly‐n‐vinylpyrrolidone by in‐situ polycondensation

AbstractThe molecular composites of polyimide (PI) with poly‐n‐vinylpyrrolidone (PVP) were successfully synthesized by in‐situ polycondensation of the rigid polymer in the matrix polymer solution. A strong acid‐base interaction between the polyamic acid (the precursor of PI) and the PVP was confirmed experimentally. By this specific interaction the miscibility of PI with PVP was substantially improved. The PI dispersed in the PVP matrix polymer on a molecular level or nearly molecular level.

Molecular dynamics simulations of PVP kinetic inhibitor in liquid water and hydrate/liquid water systems

The possible effects of PVP (poly(N-vinylpyrrolidone)) on the properties of liquid and water in clathrate hydrate has been investigated using NVT molecular dynamics simulations. A model for a monomer of the PVP polymer is immersed in three systems, liquid water, a unit cell of a hydrate in liquid water with a hydrate former and a third system where some of the liquid water molecules of this last system are replaced by a PVP monomer. Both molecular dynamics simulation and integral equation theory predict hydrogen bonding between the double bonded oxygen in the PVP ring and hydrogens in water. For the composite system, the PVP monomer has a preference for hydrogen bonding to hydrogens from the water molecules at the surface of the hydrate lattice. The simulations indicate that the PVP monomer tends to orient perpendicular to the hydrate surface. For the model systems in this study PVP may form hydrogen bonds with liquid water through the double bonded oxygen in the ring. When a hydrate crystal is immersed i...

Molecular dynamics simulations of PVP kinetic inhibitor in liquid water and hydrate/liquid water systems

The possible effects of PVP (poly(N-vinylpyrrolidone)) on the properties of liquid and water in clathrate hydrate has been investigated using NVT molecular dynamics simulations. A model for a monomer of the PVP polymer is immersed in three systems, liquid water, a unit cell of a hydrate in liquid water with a hydrate former and a third system where some of the liquid water molecules of this last system are replaced by a PVP monomer. Both molecular dynamics simulation and integral equation theory predict hydrogen bonding between the double bonded oxygen in the PVP ring and hydrogens in water. For the composite system, the PVP monomer has a preference for hydrogen bonding to hydrogens from the water molecules at the surface of the hydrate lattice. The simulations indicate that the PVP monomer tends to orient perpendicular to the hydrate surface. For the model systems in this study PVP may form hydrogen bonds with liquid water through the double bonded oxygen in the ring. When a hydrate crystal is immersed in the liquid water phase this hydrogen bonding is shifted towards the hydrate due to a more favourable Coulomb interaction involving hydrogens from more than one water molecule at the hydrate surface. The PVP monomer has a preference for perpendicular orientation with respect to the hydrate surface. A scheme is suggested for the characterization of kinetic hydrate inhibitors based on molecular dynamics simulations and on three basic properties. In addition to the energy between the active groups of the inhibitor and hydrate water another point of focus is the free energy changes in the interactions between the inhibitor and water as the charges are changed from zero to the original model charges. In particular the difference between this integral for the (hydrate water)–(PVP monomer) interaction and the (liquid water)–(PVP inhibitor) interaction should reflect the driving forces in freezing the inhibitor out from the liquid water phase and onto the hydrate surface. The third property in the characterization scheme is the diffusivities of groups connecting to the hydrate crystal, relative to the diffusivities of the hydrate crystal. Results are presented from simulations where a small cavity with a methane model as a guest is immersed in liquid water with free methane molecules at a temperature of 150K. Changes in structure, diffusivities and energy indicate a tendency towards a more solid–like structurde around the cavity.

Oxidative polymerization of pyrrole in polymer matrix

AbstractThe oxidative matrix polymerization of pyrrole (Py) by Ce(IV) in the presence of Polyacrylic acid (PAA) has been studied to obtain water‐soluble and insoluble products. The role of the PAA, Pyrrole, and Ce(IV) concentration, order of component addition, the structure of polymer matrix (PAA, Hydroxy Ethyl Cellulose (HES), Poly‐N‐vinylpyrrolidone (PVP)], and model unit of PAA (propionic acid), on the polymerization system were investigated.Interaction of PAA with insoluble polypyrrole (PPy) and the interpolymer complex formation were investigated along with the aggregation of PPy onto the matrix polymer followed by spectral shifts. FTIR results of insoluble products obtained from the PAA–Py–Ce(IV) system and solubility of the system is explained in light of the mechanism of the polymerization of pyrrole on the polymer matrix. © 1995 John Wiley & Sons, Inc.

Effect of water-soluble photoinitiator on the adhesion between composite and tooth substrate

The effectiveness of a water-soluble photoinitiator in a dentin primer was examined by measuring the tensile bond strength between the composite and tooth substrate treated with the primer. The water-soluble photoinitiator, 2-hydroxy-3-(3,4 dimethyl-9-oxo-9H-thioxanthen-2-yloxy)-N,N,N-trimethyl-1-propanaminium chloride (QTX) was dissolved into an aqueoous solution of methoxy-nonaethyleneglycol monomethacrylate (M9G) or poly-N-vinylpyrrolidone (PNVP), and these aqueous solutions were used as primers. The combination of 0.5 M EDTA pretreatment and 1% QTX - 35% PNVP aqueous solution priming produced the highest bond strength. A mixture of dentin fractures and interfacial failure between the dentin and the resin was observed in the test specimen. This dentin priming combination was also effective in improving the bond strength to enamel pretreated with EDTA.

Poly- N-vinylamides, complexation and conformational changes in aqueous solution

Interaction between small molecules (iodine and 1-anilinonaphthalene-8-sulphonate) and poly- N-methylacetamide (PVMA), poly- N-vinylcaprolactam (PVCL), poly- N-vinylpyrrolidone (PVP) and copolymers of N-vinyleaprolactam with N-vinylpyrrolidone (CP VCL-VP) and with N-vinyl- N-methylacetamide (VMA) were studied. All the polymers formed complexes with the small molecules. The stability constant for the complexes with the probe increases in the series PVMA < PVP < copolymer < PVCL indicating the essential role of hydrophobic interactions in the complex formation. With increasing temperature of aqueous solution from 18 to 33°, the constant decreased for PVP, PVMA and copolymers with low VCL content and increased for PVCL. A folding of PVC coils was observed over the temperature range, demonstrating a relationship between the conformational changes of macromolecules and the polymer complex formation. Addition of PVCL, PVMA and PVP to aqueous I 3 − solution brings about a shift of λ max from 350 nm for free triiodide ions to 372, 367 and 364 nm respectively. It is explained by different dipole moments of the side substituents. The stability constant for the polymers and I 3 − was estimated as approx. 10 5 M. The ability of the polymers to form complexes depends on chainlength. The greatest loss of the ability was observed for PVCL with M n changing from 6 × 10 3 to 2 × 10 3. Interaction of the polymers with I 3 − is accompanied by a conformational shrinking of coils. In the case of the probe, forces of electrostatic repulsion between negative charges of sulphonate groups result in an unfolding of polimer coils.

Chromatography of acid phytohormones on columns of Sephadex LH‐20 and insoluble poly‐N‐vinylpyrrolidone, and application to the analysis of conifer extracts

The chromatographic behaviour of abscisic acid (ABA), indole‐3‐acetic acid (IAA), phenylacetic acid (PAA), and gibberellins A1, A4, A8, A9, A13 and A20 on columns of Sephadex LH‐20 and insoluble poly‐N‐vinylpyrrolidone (PVP) eluted with buffers of different pH values is described. PVP shows considerable batch differences that must be carefully checked. Chromatography of acidic ethyl acetate‐soluble fractions of Scots pine (Pinus sylvestris L.) extracts at pH 4.5 resulted in great losses of phytohormones, due to poor solubility of the extracts. If the extracts were applied to the column dissolved in buffer of pH 7.5, subsequent elution at pH 4.5 was possible with only small losses. The performance of the chromatographic column was strongly affected by the application volume. A combined PVP/Sephadex LH‐20 column eluted at pH 4.5 allows remarkable purification of pine and spruce (Picea abies (L.) Karst.) extracts, collection of IAA in a fraction that can be directly analyzed by e.g. the indolo‐α‐pyrone method, and collection of another fraction containing ABA, PAA and probably most of the known C19‐gibberellins; whereas the C20‐gibberellin A13 is eluted later (with IAA).

Suppression of IgE antibodies to the (4-hydroxy-3-iodo-5-nitrophenyl)acetyl (NIP) group and induction of NIP-specific suppressor cells with NIP-poly-N-vinylpyrrolidone conjugates.

The capacity of (C57BL/6 x DBA/2)F1 mice to produce anti-(4-hydroxy-3-iodo-5-nitrophenyl)acetyl (NIP) IgE antibodies, as a result of immunization with 1 microgram of NIP2-ovalbumin (OA) in the presence of A1(OH)3, was specifically suppressed by treatment of mice, either before or after immunization, with tolerogenic conjugates consisting of the hapten coupled to poly-N-vinylpyrrolidone (PVP) with an average mol. wt of 10 000. The suppression was hapten-specific, since it did not affect the immune response of the host to OA. The unresponsive state of the spleen cells of mice which had been tolerized with respect to NIP was maintained even after cell transfer into X-irradiated, syngeneic recipients and was shown to be due to hapten-specific suppressor cells. However, the splenic B cells of these mice did not possess any suppressive activity. The generation of an effective number of suppressor cells required between 1 and 2 days following the administration of the tolerogen. The suppressive effects observed on adoptive transfer could not be attributed to the carry-over of the tolerogen, which might have been associated with the spleen cells of the donor mice, since the transfer of B cells of tolerized mice or of mice which had received 2 mg of the tolerogen 2-24 h before cell transfer did not abrogate the capacity of spleen cells of immune mice to mount an anti-NIP response. Hence, it may be concluded that NIP2-PVP induced, in addition to a probable receptor of blockade of B cells, a central inhibitory mechanism which led to the development of an effective number of suppressor cells within 1 to 2 days after administration of NIP2-PVP.

Infrared analysis of the hydration of poly-N-vinylpyrrolidone

The interaction between poly-N-vinylpyrrolidone (PV) and D 2O molecules has been investigated by IR-spectroscopy. Spectrum parameters have been measured for the absorption bands of PVP in the spectra of hydrated polymer films and solutions with various molar ratios R m=[D 2O] : [PVP], and 0 ⩽ R m ⩽ 260. Various states of PVP lactam rings relative to R m have come to light. With R m=0, the majority of the CO groups in PVP interact slightly with CH 2 groups of the polymer by a donor-acceptor mechanism, while other CO groups remain free. The hydration of PVP is realized through two unshared pairs of electrons of carbonyl oxygens (unshared pairs of p-electrons of nitrogen atoms do not participate in hydration of the polymer). Associates of lactam pendants with one H 2O molecule (at R m<1·7—with two H 2O molecules) were found in the case of low degrees of hydration ( R m<1·7) of PVP films. Associates With one and two H 2O molecules are in equilibrium in solutions of PVP in water ( R m = 260). If the solution temperature is lowered, this equilibrium is displaced towards formation of associates with two molecules of water.

Preparation and physical-chemical characterization of poly-N-vinylpyrrolidone-insulin.

In an attempt to modify the structure of insulin, the hormone was coupled by covalent linkage to poly-N-vinylpyrrolidone (PVP). PVP-insulin is soluble in aqueous solution and was purified by column chromatography. Special care was taken to check for a possible leakage of insulin from the synthetic polymer. The amount of bound insulin was determined by quantitative amino acid analysis after acid hydrolysis. After protection of the N-terminal glycine residue of the A-chain by citraconylation, a biologically active PVP-insulin was obtained. The molecular weight determined by analytical ultracentrifugation and column chromatography was 50 000-60 000. The biological activity of the coupled hormone was between 0.5 and 7% when compared with native insulin in the system in vitro. The immunological activity was about 20-50%.

The inhibitory effect of oak leaf litter tannins on the growth of fungi, in relation to litter decomposition

The effects of oak leaf litter tannins on nineteen different species of fungi, freshly isolated from decomposing oak leaf litter were assayed. Two different approaches to the assay were taken. The first was by difference in effects induced by aqueous extracts and aqueous extracts treated with poly- n-vinylpyrrolidone (PVP) and the second by assay of purified tannins in artificial aqueous medium. Of the nineteen fungal species assayed, fourteen were inhibited. Four species considered to be most important fungal decomposers were inhibited. Some aspects of the ecology of some of the fungi and their reaction to tannins are discussed.

Selectivity properties of poly-n-vinyl pyrrolidone in column chromatography of nucleotides, their derivatives, and related compounds: a preliminary report

Insoluble poly-N-vinyl pyrrolidone (PVP) has been found to possess selectivity properties toward various nucleotide derivatives and can be used for column chromatography employing water as eluent. Compounds emerge from the columns in this order: nucleotides, pyrimidines, purines. Total elution volumes and times for the series of compounds investigated are 45 ml (5 h) with use of a 0.9 x 22.3 cm column and 20 ml (65 min) with use of a 0.9 x 10.8 cm column.