Vinylpyridine Polymers Research Articles

STUDY OF THE LIQUID-PHASE HYDROGENATION OF BENZENE IN THE PRESENCE OF METAL-POLYMER COMPLEXES BASED ON POLYVINYLPYRIDINES

The liquid-phase hydrogenation of benzene on metal-polymer complexes, which were prepared on vinylpyridine polymers containing functional groups and salts of transition metals such as nickel, palladium, and platinum, was studied. Poly-4-vinylpyridine and poly-2-methyl-5-vinylpyridine were used as vinylpyridine polymers. Hydrogenation was carried at a temperature of 20-600 C. The study additionally focussed on the influence of the nature of the medium on the benzene hydrogenation process on poly-4-vinylpyridines. It has been established that in the presence of a platinum-poly-4-vinylpyridine complex, the reaction of liquid-phase hydrogenation of benzene, not only the product of complete hydrogenation, but also products of incomplete hydrogenation, cyclohexene, are formed. It was also found that the nature of the medium affects the yield of cyclohexane and cyclohexene selectively and effectively

Influence of Carbon Dioxide on the Glass Transition of Styrenic and Vinyl Pyridine Polymers: Comparison of Calorimetric, Creep, and Rheological Experiments

The glass transition of amorphous polymers determines the mobility of polymer chains and the time scale of relaxation processes. The glass transition temperature is reduced by the presence of low molecular weight molecules, e.g., dissolved gases or organic solvents. The quantitative knowledge of reduction of the glass transition temperature caused by the addition of carbon dioxide in a polymer melt is highly relevant for foam extrusion. However, measurement of the reduction of glass transition temperature caused by gas loading has to be performed under elevated pressure which implies high experimental efforts. In this work, we discuss and compare three methods for determination of the influence of carbon dioxide on thermal properties of amorphous polymers, i.e., calorimetric measurements, creep tests, and rheological experiments. The advantages and disadvantages of these methods are elucidated. Furthermore, the influence of molecular structure of the styrenic and vinylpyridine polymers on the glass transition temperature is discussed. Polystyrene generally shows the highest reduction of glass transition temperature. Poly(2-vinylpyridine) and poly(4-vinylpyridine) show a slightly less pronounced behaviour in comparison to polystyrene because of the lower polarity of polystyrene. Poly(α-methyl styrene) is associated with a different dependence of glass transition temperature on gas loading in calorimetric and rheological experiments.

Nonwoven membrane modifi cation by 4-vinyl pyridine grafted polyvinyl alcohol for resistance the adhension of bacteria

Membranes suffer from operational problems due to fouling in water filtration. Fouling is caused by the build-up of chemicals, bioorganic materials, and biofilms at the membrane surface. The focus of this study was the fabrication and characterization of 4-vinyl pyridine grafted polyvinyl alcohol (PVA-g-4VP) and the modifi cation of nonwoven membrane (NWF) for the prevention of bacterial attachment. The graft copolymerization using Ce(IV) as an initiator was carried out in an aqueous solution. With keeping other conditions constant, the optimum conditions were shown as following: [Ce(IV)]=4 mmol/l, [4VP]=0.15 mol/l, reaction temperature=60°C, reaction time=240 min. NWF membranes were modified by coating of PVA-g-4VP with different graft concentrations, and quaternization of the pyridine groups with benzyl bromide. A significant surface enrichment of vinyl pyridine polymer side chains was observed by Fourier transform infrared-attenuated total refl ectance. The permeability of the membrane was reduced afte...

Ceria-Supported Vinylpyridine Polymers: Synthesis, Characterization and Application in Catalysis

A simple, one-step synthesis of 4-vinylpyridine polymer crosslinked with 2% divinylbenzene [poly(4vp-dvb)] anchored with ceria nanocrystals via in situ reactions that involve simultaneous formation of the polymer and ceria nanocrystals is presented. The polymer support is formed by free radical suspension polymerization of the monomers, while ceria nanocrystals are generated from CeCl3·7H2O by the homogeneous precipitation method in a single pot. The polymer supports were characterized by XRD, TEM, SEM, ESCA, and TGA and then tested for their ability as heterogeneous recyclable catalysts in a Biginelli reaction. The catalytic activities of these supports were found to be far superior to the two-step conventional one and simultaneous microporous bead counterparts. Reusability is an added advantage over the other regularly used cerium-based catalysts in aqueous media. The significant increase in the catalytic activity is due to the higher Ce/N ratio and predominance of well-defined and more reactive exposed planes of ceria nanocrystals on the new supports. Such catalysts are of great importance due to environmental, practical and economical concerns.

Poly(2-vinylpyridine)- and poly(4-vinylpyridine)-graft-poly(vinylidene fluoride) copolymers and their pH-sensitive microfiltration membranes

Thermally-induced molecular graft copolymerization of 2-vinylpyridine (2VP) and 4-vinylpyridine (4VP) with the ozone-preactivated poly(vinylidene fluoride) (PVDF) was carried out in N-methyl-2-pyrrolidone (NMP) solution to produce, respectively, the 2VP-g-PVDF and 4VP-g-PVDF copolymer. In general, the graft concentration of both the 2VP-g-PVDF and the 4VP-g-PVDF copolymers increased with the respective monomer feed ratio used for graft copolymerization, with 4VP exhibiting a higher graft copolymerization efficiency than 2VP. Microfiltration (MF) membranes were prepared by phase inversion in aqueous solutions of different pH values and from copolymers of different graft concentrations. The surface composition of the copolymer MF membranes was investigated by X-ray photoelectron spectroscopy (XPS). A significant surface enrichment of the more hydrophilic vinylpyridine polymer side chains was observed. However, the surface graft concentration of the MF membranes decreased with the decrease in pH value of the casting bath. The mean pore size of the 4VP-g-PVDF and 2VP-g-PVDF MF membranes generally increased with the decrease in concentration of the casting solution, the decrease in pH value of the casting bath, and the increase in graft concentration. At a fixed graft concentration, the flux of the aqueous solution through the 4VP-g-PVDF MF membrane exhibited a higher pH-sensitivity than the flux through the corresponding 2VP-g-PVDF MF membrane, as a result of a higher degree of protonation of the former by the permeate.

Reactions on polymers with amine groups. I. Reactions of vinylpridine polymers and of their model compounds with unsaturated carboxylic acids

AbstractThe reactions of vinylpyridine polymers with α,β‐unsaturated carboxylic acids such as acrylic, methacrylic, crotonic, itaconic, cinnamic, fumaric, and maleic acids were studied. It was found that, when reacted with acrylic, itaconic and fumaric acids. poly(4‐vinylpyridine) gave macromolecular betaine products while with maleic acid, betaine as well as the corresponding salt was obtained. Poly(2‐vinylpyridine) reacted with the same acids as poly(4‐vinylpyridine) gave only the salts. No significant changes were observed with the two polymers when reacted with methacrylic, crotonic, and cinnamic acids. To attempt to rationalize these observations with the two macromolecular tertiary amines, the reactions of 4‐methyl and 2‐methylpyridines with the same carboxylic acids were investigated. The 1H‐NMR methodology was generally applied to elucidate the chemical structure obtained. © 1995 John Wiley & Sons, Inc.

An improved synthetic method of ampicillin using vinylpyridine polymer as an acid scavenger

An improved synthetic method of ampicillin using vinylpyridine polymer as an acid scavenger

Preparation of new hydrophilic poly‐vinylpyridine beads and their application to immobilization of urease

AbstractMacroporous hydrophilic poly‐vinylpyridine beads were prepared by suspension copolymerization of 4‐ (or 2‐)vinylpyridine and hydrophilic cross‐linking agents, such as ethylene glycol dimethacrylate (1EG) and tetraethylene glycol dimethacrylate (4EG), and their physical properties were studied. Immobilized enzymes were obtained by adsorption of urease on vinylpyridine polymers and commercially available hydrophobic polymers. The poly‐4‐vinylpyridine resin crosslinked with 4EG (degree of crosslinkage, 25%) showed higher water regain, larger average pore radius, and the highest adsorption of urease. Leakage of urease from immobilized urease was scarcely observed in the buffer solution used. The hydrophilicity and hydrophobicity of support affected markedly the enzymatic reaction of the immobilized enzyme. As one of the applications of the polymer‐supported urease, blood urea nitrogen in human sera was determined.

Liquid chromatographic characterization of porous vinylpyridine polymer as a weak anion-exchange column packing

The retention behaviour of aromatic acids on a pyridine polymer column in ion-exchange high-performance liquid chromatography was investigated, and compared with that on a pyridinium polymer column. The effect of the eluent pH on the capacity factor, k′, of the acids on these polymer columns may be explained by the extent of dissociation of both the solute and the polymer. The relationship between the concentration of methanol in the and k′ showed that both polymer columns exhibit similar hydrophobic interactions with the solutes. On the pyridine polymer column, good resolution of structural isomers of aminobenzoic and hydroxybenzoic acids was obtained. It is suggested that undissoiciated pyridyl groups contribute to the solute retention.

Uses of a vinylpyridine polymer in undergraduate organic synthesis

Polymer chemistry is becoming an increasingly important aspect of industrial and synthetic chemical processes. Yet many undergraduate chemistry curricula provide little exposure to polymeric reagents and their diverse applications for organic syntheses. One recently introduced polymeric reagent that can he adapted to the parameters of the undergraduate laboratory is poly-4-vinylpyridine (PVP, I), a crosslinked 4-vinylpyridine copolymer (R-8050, Reilly Tar and Chemical CO.~) that can he used instead of pyridine or other tertiary m i n e s in a wide variety of reactions. The granular nature of this polymer and its insolubility in all organic solvents allows for its isolation by simple fdtration. After washing with the reaction solvent, the polymer or its derivatives may he recycled or regenerated repeatedly with no apnarent loss of activitv. Also the solid nature of the polvmer hhviates the use of liquid pyridine, therehy avoiding th;'ohiectionahlr odor. flammahilitv. and toxicity associatrd with the liquid reagent. We have investigated a number of reactions that can be carried out conveniently in undergraduate laboratory courses and report the results.

Characterization of vinylpyridine polymer columns for high-performance liquid chromatography

Four spherical 2- or 4-vinylpyridine polymers (10–15 μm particle diameter), cross-linked with divinylbenzene and having different surface properties, are proposed as packing materials in high-performance liquid chromatography. The retention behaviour of various compounds on columns packed with these polymers was compared with that on a styrene—divinylbenze copolymer column using methanol as the mobile phase. Interaction between polyhydric phenols and vinylpyridine polymers occurred more effectively in 4-vinylpyridine polymer than 2-vinylpyridine polymer, and porous 4-vinylpyridine polymer with 20% cross-linking provided the best peak resolution in the separation of the phenols. The retentions of acidic and basic compounds were correlated with the extent of acidity or basicity of the compounds. The effect of solvent strength on the retention of the selected compounds was also investigated by using methanol containing water or n-hexane.

Sorption of phenolics onto cross-linked poly(4-vinyl pyridine)

In order to explore the possibility of using cross-linked polymer of 4-vinyl pyridine as sorbent for removal, separation and recovery of phenolic species, the sorption behaviour of a number of model phenolic compounds, differing from each other in acidity and molecular size, has been studied, using the vinyl pyridine polymer both in the free-base form and in salt form. The phenolic compounds used include phenol, p-cresol, p-chlorophenol, p-nitrophenol, m-aminophenol, polyphenol and lignin. The sorption of phenolic compounds with the free-base resin affords significantly greater sorption capacity than that with the same resin used in the salt form. The level of pH of the aqueous medium has a marked influence on the sorption of phenols by free-base PVP, the maximum sorption taking place at lower pH for more acidic phenols, which is in accord with the hydrogen bonding mechanism of phenolics sorption. The Freundlich isotherm equation provides an adequate fit to the sorption data, while the coefficient of the isotherm equation bears a distinct relationship to the acidity of the phenolic sorbate. A simplified rate equation based on the concept of linear driving force fitted the initial sorption rate data well, yielding a value for the particle-diffusion control rate coefficient for each phenolic species. Substituted phenols have lower intraparticle diffusivities than phenol, with the diffusivity decreasing as the size of the substituent group increases. Lignin undergoes much stronger interaction with the resin than do the other phenols. Consequently, while the sorbed phenols are all easily eluted by dilute alkali, lignin sorbed onto the resin is however removed only with considerable difficulty.

Polyvinyl pyridines as flocculating agents

High molecular weight poly 2- and 4-vinyl pyridines were synthesized by ionic polymerisation and their flocculation efficiency tested against kaolin and silica dispersions at pH 3. Low additions of the polymers, around 3 parts per 103 parts solid, destabilize the dispersions and clarify silica dispersions to a remarkable extent; however, over-addition of polymer leads to partial restabilization. The flocculation efficiency improves with increase of solids content, especially with clay dispersions. Flocculation efficiency increases with polymer molecular weight, especially over the lower part of the range covered, but is relatively independent of pH in the range 2–4. Quaternization of poly(4-vinyl pyridine) with bromobutane produces a good flocculant for aqueous silica dispersions in which the degree of restabilization on over-dosing depends on the KCI content. TheN-oxide derivatives of the vinyl pyridine polymers do not affect the colloidal stability of silica dispersions. The observations are interpreted in terms of bridging flocculation by the cationic polymer molecules between anionic surface sites on the solid particles.

Porous vinylpyridine polymers as column packings for gas chromatography

Three porous vinylpyridine polymers (I-III), cross-linked with divinylbenzene and having different surface properties, are presented as column packings in gas chromatography. Primarily by separating mixtures of amines, the efficiency of these columns is compared with that of Chromosorb 103. Polymer II is suitable for the separation of lower boiling aliphatic amines, whereas for rapid analyses of higher boiling amines and aminoalcohols polymer III can be used successfully and with less tailing.

A method of determining the composition of graft co-polymers of cellulose with vinyl pyridine polymers

A method of determining the composition of graft co-polymers of cellulose with vinyl pyridine polymers

Properties of the Dilute Solution of Poly-2-methyl-5-vinylpyridine

Abstract Nine fractionated samples of poly-2-methyl-5-vinylpyridine (PMVP) have been investigated by viscosity and light-scattering measurements at 25°C. In the range of the molecular weights from about 1×105 to 1×106, the following relationship between the intrinsic viscosity and the molecular weight in methanol has been obtained: [η] =0.80×10−4Mw0.76. The unperturbed molecular dimensions have been obtained using the recent theories of the solution behavior of high polymers. The results have been compared with those of other vinylpyridine polymers and polystyrene, and it has been found that the degree of the extension of PMVP is almost the same as those of the other polymers.

Rubbers from Basic Monomers. Vinylpyridine Polymers

Abstract Interest in vinylpyridine and vinylpyridine derivatives as monomers for production of synthetic rubber was evidenced immediately prior to World War II. In 1939 and 1940, European patents were issued on polymerization of vinylpyridines and their copolymerization with other monomers. Research in the United States on vinylpyridines and their derivatives as comonomers began in the early 1940's. Much of the early work was conducted under the Government synthetic rubber program with work carried out by several of the participating universities and rubber companies. At that time, vinylpyridine rubbers created a considerable amount of interest in the rubber industry. Compared to the 122° F butadiene/styrene copolymer then in use, butadiene/vinylpyridine copolymers displayed a superiority in several properties, notably tensile strength, tear resistance and resistance to cut growth. A number of terpolymers containing vinylpyridine type monomers were also investigated and these, with some exceptions, exhibited the same general advantages and disadvantages as the two-component copolymers. Some difficulty was encountered in early polymerization of vinylpyridine copolymers on a large scale, chiefly in preflocculation and lack of proper control over polymer viscosity and conversion rates. These problems were lessened somewhat in the polymerization of three-monomer systems. Processing difficulties were also encountered arising from incompatibility of vinylpyridine copolymers with other rubbers and a high rate of cure resulting in scorching tendencies. Treadwear results of tires made with these rubbers were encouraging but again complications appeared in the form of tread separations and an excessive increase in hardness after use. Because of the above-mentioned problems, together with the introduction of improved 41° F butadiene/styrene rubber, interest in these rubbers waned somewhat after World War II. More recently, however, interest in vinylpyridine rubbers has risen due to commercial availability of new monomers and the possibility of utilizing the reactivity of vinylpyridine polymers through new compounding techniques.