Copolymers Of 4-vinylpyridine Research Articles

Hybrid membranes based on silica and 2-hydroxyethylmethacrylate–4-vinylpyridine copolymers

4-Vinylpyridine–2-hydroxyethylmethacrylate copolymers have been synthesized by radical copolymerization. The composition and properties of the copolymers have been studied; the reactivity constants of the comonomers have been calculated. Sol–gel synthesis involving the resulting copolymers and tetraethoxysilane has yielded hybrid membranes comprising a polymer matrix with uniformly distributed hydrated silica particles and exhibiting a proton conductivity of up to 1.85 × 10−2 S/cm, an ion-exchange capacity of 2.1 meq/g, a heat resistance of 412°С, a tensile strength of 55.5 MPa, an elongation at break of 15%, and a proton-conductivity activation energy of 12 ± 2 kJ/mol.

Thermal decomposition of anion-exchange resin based on copolymer of 4-vinylpyridine

Formal kinetic model is suggested on the basis of experimental studies of the heat-release kinetics in decomposition of an anion-exchange resin, copolymer of N-methyl-4-vinylpyridinium chloride and divinylbenzene. The model makes it possible to determine the service life of the resin in the temperature range 100–170°C in optimization of the process in which monosilane is synthesized from trichlorosilane with the resin used as a catalyst.

Preparation of a novel molecularly imprinted polymer for the highly selective extraction of baicalin.

The selective extraction of baicalin is important to its quality control especially when the matrices are complicated. In this work, a novel molecularly imprinted polymer was prepared for the selective extraction of baicalin in herbs. The molecularly imprinted polymer was synthesized by the copolymerization of 4-vinyl pyridine and ethylene glycol dimethacrylate in the presence of baicalin by a precipitation polymerization method. After the optimization of parameters for molecularly imprinted polymer preparation, including the functional monomer, porogen, sampling solvent, and washing solvent, good selectivity was obtained, with an imprinting factor of about 4, which is much better than that achieved by the bulk-polymerization method. The performances of the prepared molecularly imprinted polymers were systematically investigated, including adsorption kinetics, isotherm experiment, and Scatchard analysis. On the basis of the good adsorptive capability of the prepared molecularly imprinted polymer, it was also applied for the pretreatment of baicalin in Scutellaria baicalensis Georgi. The result showed that most of the matrices were removed and baicalin was selectively enriched.

The potential of 1H NMR spectroscopy for studying the kinetics and mechanism of controlled radical polymerization with reversible chain transfer

The potential of 1H NMR spectroscopy for determining the constants of chain transfer to a symmetric bifunctional agent of reversible chain transfer and for studying the changes in the current concentrations of the initial and final agents formed during the replacement of one leaving group with a polymer (oligomeric) radical of the agents of reversible chain transfer during the homopolymerization of N-vinyl succinimide, the homopolymerization of vinyl acetate, and the copolymerization of 4-vinylpyridine and tert-butyl acrylate in the presence S,S-dibenzyltrithiocarbonate is studied. The correct calculation of the constants of chain transfer is shown to be possible only during agreement of the studied system with the taken scheme of polymerization with reversible chain transfer, a minimum contribution of side reactions, and signal separation that is sufficient for the quantitative analysis of initial and polymer (monosubstituted) agents of reversible chain transfer in the 1H NMR spectra. The lower limit of the constants of transfer to the polymer agents of reversible chain transfer is estimated, and the great efficiency of these agents in comparison to that of the initial low-molecular-mass ones is directly confirmed. A complex of necessary investigations to study any new polymerization system where the controlled radical homoand copolymerization with reversible chain transfer in the presence of symmetric trithiocarbonates occurs is performed.

Synthesis and application of reduced graphene oxide and molecularly imprinted polymers composite in chemo sensor for trichloroacetic acid detection in aqueous solution

This work presents the fabrication of a simple, cheap and fast thin film chemo sensor for detection of trichloroacetic acid (TCAA) in aqueous solutions. Reduced graphene oxide (RGO) based molecular imprinted polymers (MIP) chemo-sensor has been developed. The recognition of TCAA was achieved by imprinted polymers synthesized by copolymerization of 4-vinylpyridine (4-VP) and a crosslinking monomer ethylene glycol dimethacrylate (EDGMA) in acetonitrile using bulk polymerization method. Adsorption studies to determine the rebinding properties of the MIP with the template were conducted using UV Visible spectrophotometer. The fabricated sensor exhibited high recognition ability and affinity for HAA in comparison with the non-imprinted one which was employed as a control, this indicated that the MIP could selectively rebind with TCAA. Reduced graphene oxide (RGO) was used to improve conductivity of the sensor; RGO was obtained from reduction of graphene oxide (GO) synthesized using modified Stauddmer and Hummers method. Polysulphone was used in solution blending of MIP and RGO to form a hybrid which was deposited between two gold plated electrodes by spin coating to form a thin film. The performance of the imprinted sensor was studied using a homemade circuit. The results demonstrate that the sensor based on TCAA-imprinted polymer is fast, cheap and sensitive screening method of TCAA in drinking water.

PH- and temperature-responsive amphiphilic diblock copolymers of 4-vinylpyridine and oligoethyleneglycol methacrylate synthesized by RAFT polymerization

Diblock copolymers of 4-vinylpyridine (4VP) and oligoethyleneglycol methyl ether methacrylate (OEGMA) were synthesized for the first time using RAFT polymerization technique as potential drug delivery systems. Effects of the number of ethylene glycol units in OEGMA, chain length of hydrophobic P4VP block, pH, concentration and temperature on the solution behavior of the copolymers were investigated comprehensively. Copolymer chains formed micelles at pH values higher than 5 whereas unimeric polymers were observed to exist below pH 5, owing to the repulsion between positively charged P4VP blocks. The size of the micelles was dependent on the relative length of blocks, P4VP and POEGMA. Thermo-responsive properties of copolymers were investigated depending on the pH and length of P4VP block. The increase in the length of P4VP block decreased the LCST substantially at pH 7. At pH 3, LCST of copolymers shifted to higher temperatures due to the increased interaction of copolymers with water through positively charged P4VP block.

Evaluation of ion imprinted polymers for the solid phase extraction and electrothermal atomic absorption spectrometric determination of palladium in environmental samples

The complexes of Pd(II) with ammonium pyrrolidinedithiocarbamate (APDC), N,N′-diethylthiourea (DET) and dimethylglyoxime (DMG) were prepared and imprinted into a polymeric network. The ion-imprinted polymers (IIPs) were synthesized by copolymerization of 4-vinylpyridine (VP) and styrene as functional monomers and divinylbenzene as a cross-linking agent in the presence of 2,2-azo-bis-isobutyronitrile as an initiator. The influence of sample volume, pH and flow rate on the extraction efficiency of Pd was studied under dynamic conditions. Pd(II) could be quantitatively retained on each of the studied sorbents at the pH range of 0.5 to 1.0, and eluted with an acidic solution of thiourea. The polymer with the imprinted Pd-DET-VP complex offered the highest selectivity for Pd(II) over certain matrix components, such as Pt(IV), Ni(II) and Cu(II). The low sample pH is an important advantage of the separation procedure, as it allows an effective separation of Pd(II) from complex environmental matrices. The developed separation method was successfully applied to the electrothermal atomic absorption spectrometric (ETAAS) determination of trace amounts of Pd in tap and river water, grass, and certified platinum ore (CRM SARM 7 and SARM 76) samples with reproducibility below 6.5%. The detection limit for Pd(II) obtained by ETAAS after the pre-concentration on Pd-DET-VP polymer was 0.012 ng mL−1 for 75 mL sample volume.

Antimicrobial surface coatings for a permanent percutaneous passage in the concept of osseointegrated extremity prosthesis

The clinical implementation of percutaneous implants is still limited owing to infections at the side of the stoma. In our concept, this issue is addressed by designing copolymer surface coatings possessing biocompatibility and antimicrobial activity to improve the maintenance of a physiological skin seal at the skin-implant interface. Different copolymers with surface-active phosphonate and antimicrobial cationic groups were designed. Thus, coated titanium samples were cultured with bacterial strains or fibroblasts, respectively. Antimicrobial impact was evaluated by imaging the reduction of bacterial adherence. Biocompatibility was displayed by fibroblast proliferation and morphology. A variety of copolymers of 4-vinylpyridine with vinylbenzylphosphonate or dimethyl(2-methacryloyloxy-ethyl) phosphonate were prepared by free radical polymerization. The optimized polymer coating (copolymer D) showed a reduction of adherent bacteria up to 95%, with only a slight reduction in the adherence of human fibroblasts compared with blank titanium controls. In this study, we demonstrate in vitro that polymer surface coatings can be simultaneously antimicrobial and biocompatible. We consider this to be a promising technology for the realization of a permanent aseptic percutaneous passage as needed for the advancement of osseointegrated limb prosthesis.

An imprinted polymer for removal of Cd2+ from water samples: Optimization of adsorption and recovery steps by experimental design

A new ion-imprinted polymer (IIP) was synthesized by copolymerization of 4-vinylpyridine (monomer), ethyleneglycoldimethacrylate (cross-linker) and 2,2-azobis-isobutyronitrile (initiator) in the presence of Cd2+ and quinaldic acid (complexing agent). It was found that the adsorption capacity of IIP and blank polymer were 45.0 and 6.2 mg g−1, respectively. The relative selectivity coefficients of the imprinted polymer for different binary mixture were also calculated. Compared to non-imprinted polymer (NIP), the IIP had higher selectivity for Cd(II). The IIP was used as a sorbent for cadmium extraction from water samples by using a simple batch extraction procedure. The effect of different parameters on Cd2+ extraction and its recovery from the IIP were evaluated and optimized by using experimental design methodology. The optimized adsorption/desorption procedure was applied for cadmium removal from the real water samples. The obtained recoveries proved that this IIP could be used for removal of trace cadmium ions from water samples.

Synthesis, Characterization and Selective Recognition of Lead Using a New Ion Imprinted Polymer Material

A new ion-imprinted polymer (IIP) material was synthesized by copolymerization of 4-vinylpyridine(VP) as monomer, ethylene glycol dimethacrylate(EGDMA) as crosslinking agent and 2,2΄-azobisisobutyronitrile(AIBN) as initiator in the presence of Pb–1,5-diphenylcarbazone(Pb-DHCB) complex. Blank non-imprinted polymer (NIP) were prepared under identical conditions without the use of lead imprint ion. The synthesized polymers were characterized by IR spectroscopy and elemental analyzer techniques. Of the several polymers synthesized, only the imprinted polymer formed with binary complex of Pb2+–DHCB showed quantitative enrichment of lead ion from aqueous solution. The relative standard deviation of the five replicate determinations of Pb (II) was3.26%. The detection limit for 150 mL of sample was 1.6 µg L-1 using flame atomic absorption spectrometry. The developed method was successfully applied to the determination of trace lead in environmental samples with satisfactory results.

Grafting of 4-Vinyl Pyridine onto Polyesters Initiated by Potassium Diperiodatocuprate(<i>III</i>)

In this article, the graft copolymerization of 4-vinyl pyridine onto poly (ethylene terephthalate)(PET) via the potassium diperiodacuprate(III)–PET redox system as an initiator was investigated in an alkaline medium. The graft copolymer was characterized with Fourier-transform infrared spectra analysis. A mechanism is proposed to explain the generation of radicals and the initiation. The effects of reaction variables, such as the initiator concentration, the ratio of monomer to PET, pH, and reaction temperature and time, are investigated, and the grafting conditions are optimized. Graft copolymers with high grafting efficiency are obtained, thus indicating that potassium diperiodacuprate(III)-PET redox system is an efficient initiator for this graft copolymerization. The quaternized PET-g-PVP (QPEVP) is proved to be an excellent adsorbent to heavy metal ions.

Assessment of ion imprinted polymers based on Pd(II) chelate complexes for preconcentration and FAAS determination of palladium

New ion-imprinted polymeric (IIP) materials were synthesized by copolymerization of 4-vinylpyridine (VP) and styrene as functional monomers and divinylbenzene as a cross-linking agent with chelating complexes of Pd(II) in the presence of 2,2-azobisisobutyronitrile as an initiator. The complexes of Pd(II) with ammonium pyrrolidinedithiocarbamate (APDC), N,N′-diethylthiourea (DET), and dimethylglyoxime (DMG) were used for this purpose. Chloroform, ethanol, and cyclohexanol were applied as porogens. The ion-imprinted polymers were tested in a flow mode as sorbents for solid-phase extraction of palladium from aqueous solutions. The conditions of Pd(II) separation on all polymers were optimized. The efficiencies of retention of Pd on different polymers in the presence of high excess of interfering ions were compared. The effect of the used porogen on the analytical performance of the prepared polymers was also investigated. The calculated sorbent capacities for Pd(II) were in the range from 9.25 mg g −1 to 13.3 mg g −1. The sorbent with Pd(II) imprinted as Pd–DMG–VP complex in chloroform was used for preconcentration of trace amounts of Pd. The detection limit for 100 mL of the sample was 5 μg L −1 using flame atomic absorption spectrometry (FAAS). The developed method was applied for the determination of Pd in water samples.

Functionalization of cotton fabric orienting towards antibacterial activity

The primary objective of modifying cotton fabric was to impart bactericidal properties to attract various fields such as defence, space and textile industrial applications. Chemically initiated graft copolymerization of 4-vinyl pyridine (4-VP) and acrylonitrile (AN) onto cotton fabric was carried out using ceric ammonium nitrate as a redox initiator. Optimum conditions pertaining to maximum percentage of grafting were evaluated as a function of concentration of initiator [CAN], concentration of nitric acid, monomer concentration, water, temperature and reaction time. Maximum grafting of 4-VP (51.63%) and AN (69.23%) was obtained respectively at optimum \( \left[ {\text{CAN}} \right] = 2.738 \times {10^{ - 2}} \) and 2.19 × 10−2 moles/L, \( \left[ {4 - {\text{VP}}} \right] = 47.55 \times {10^{ - 22}}{\text{moles}}/{\text{L}} \), \( \left[ {\text{AN}} \right] = 18.85 \times {10^{ - 22}}{\text{moles}}/{\text{L}} \), \( \left[ {{\text{HN}}{{\text{O}}_3}} \right] = 11.9 \times {10^{ - 2}} \) and 89.5 × 10−22 moles/L in 20 and 25 ml of water at an optimum temperature 70 °C and 60 °C with in 180 and 120 min. Antibacterial properties were induced into the modified cotton fabric by treating the grafted fabric with benzyl chloride. The grafted and quaternized copolymer were characterized by FTIR and Thermogravimetrical analysis. The bactericidal action of cotton fabric was tested by filtration test and it was observed that fabric grafted with 4-VP was more effective and efficient antibacterial as compared to AN grafted cotton sample.

Structure−Activity Relationships of Antibacterial and Biocompatible Copolymers

The development of polymers that are both bactericidal and biocompatible would have many applications and are currently of research interest. Following the development of strongly bactericidal copolymers of 4-vinylpyridine and poly(ethylene glycol) methyl ether methacrylate, biocompatibility assays have been completed on these materials to measure their potential biocompatibility. In this article, a new methodology for measuring protein interaction was developed for water-soluble polymers by coupling proteins to surfaces and then measuring the adsorption of copolymers onto these surfaces. Ellipsometry was then used to measure the thickness of adsorbed polymers as a measurement of biocompatibility. These results were then compared and correlated with the results of other biocompatibility assays previously conducted on these polymers, affording a greater understanding of the biocompatibility of the copolymers as well as improving the understanding of the effect of hydrophilic and hydrophobic groups that is vital for the development of these materials.

SYNTHESIS OF ORGANIC-INORGANIC HYBRID SUPPORTED ZIRCONOCENE CATALYST AND ITS CATALYSIS ON ETHYLENE POLYMERIZATION

Organic-inorganic hybrid(SAV) supported zirconocene was synthesized and its catalysis on ethylene polymerization was examined.The SAV was synthesized by copolymerization of 4-vinylpyridine with vinyl silica monomer(SA),which was modified by reacting silica with allyltrimethoxysilane(APS).After treated by MAO,the SAV was reacted with Cp_2ZrCl_2 to form organic-inorganic hybrid supported metallocene.The chemical structure and the composition of SA and SAV have been characterized by solid-state()~(13)C_NMR,XPS,and elemental analysis(EA).The SAV supported zirconocene catalyst was effective in ethylene polymerization at a relatively low MAO level(Al/Zr = 600) giving higher activity than that supported by SiO_2.

Realizing metalloporphyrin functionalization of 4-vinylpyridine copolymer via axial coordination reaction

Cobalt tetra(para-chlorophenyl)porphyrin ( CoTCPP ) and zinc tetraphenyl porphyrin ( ZnTPP ) were linked on the side chains of the copolymer of 4-vinylpyridine (4VP) and styrene (St), P(4VP-co-St), via axial coordination reactions, respectively, and the metalloporphyrin-functionalized macromolecules, CoTCPP -P(4VP-co-St) and ZnTPP -P(4VP-co-St), were prepared. Their chemical structures were characterized by FTIR and 1H NMR. The spectral properties of the two macromolecular axial coordination complexes were mainly studied, and their photophysical behavior were discussed in depth. The experimental results show that the metalloporphyrin-functionalized macromolecules, CoTCPP -P(4VP-co-St) and ZnTPP -P(4VP-co-St), can be prepared favorably through axial coordination reaction with the side pyridine groups of the copolymer P(4VP-co-St) as ligands. The two complexes have characteristic spectra similar to that of the small molecular metalloporphyrins, CoTCPP and ZnTPP , respectively. At the same time, they also display the characteristic spectroscopic property of axial coordination complexes: the electronic adsorption spectra of CoTCPP -P(4VP-co-St) and ZnTPP -P(4VP-co-St) red-shifted obviously as compared to that of CoTCPP and ZnTPP , and the fluorescence emission of ZnTPP -P(4VP-co-St) blue-shifted apparently with respect to that of ZnTPP . For CoTCPP -P(4VP-co-St) and ZnTPP -P(4VP-co-St), some polymer effects were found: (1) the bonding degree of the small molecular metalloporphyrin, CoTCPP or ZnTPP , on the side chains of the copolymer P(4VP-co-St) has a limit value because of the steric hindrance and there is a bonding degree difference between the actual value and the theoretical value; (2) for ZnTPP -P(4VP-co-St), slight energy transfer between adjacent ZnTPP units on an identical macromolecule occurs, leading to slight static quench of the fluorescence emission as the bonding density of ZnTPP units on the side chains of the copolymer P(4VP-co-St) reaches a certain value.

Study of iron(III) polymer complexes using Moessbauer spectroscopy

Metal complexes were prepared on the basis of polymer ligands with carboxylic and nitrogen-containing functionalities by complexation with iron ions in aqueous solutions of FeCl3·6H2O and FeSO4·2H2O. The degree of introduction of iron ions into the polymer matrices depended on the relative content of the functional groups in the polymers studied such as polyacrylic acid, poly-4-vinylpyridine, and poly(2-N,N-dimethylaminoethyl) methacrylate. The metal content in the polymer complexes was found to vary between 9.0 and 30.0 (for acrylic acid-based copolymers); 0.1 and 5.3 (for copolymers of 4-vinylpyridine), and 19.7 and 34.4 (for poly(2-N,N-dimethylaminoethyl) methacrylate) mg metal ions per gram of polymer carrier, respectively. An attempt was made to evaluate the structure of the Fe-containing polymeric materials by Moessbauer spectroscopy. The parameters of the Moessbauer spectra such as the isomer shift, quadrupole splitting, effective internal magnetic field, and relative weight of the partial components were consequently determined for the complexes studied at different temperatures. The results obtained proved the existence of high-spin Fe3+ ions in oxygen- or nitrogen-containing ligand environment.

In Vitro Biocompatibility Studies of Antibacterial Quaternary Polymers

Quaternized copolymers of 4-vinylpyridine and poly(ethylene glycol) methyl ether methacrylate are known to have antibacterial properties and have displayed biocompatibility in red blood cell hemolysis assays. The results from hemolysis assays have shown substantial promise, but the technique is rudimentary and only a first step toward the determination of biocompatibility. The present paper further explores the biocompatibility of these copolymers through comprehensive cell viability assays performed on Caco-2 human epithelial cells cultivated in vitro. We have shown that these copolymers are biocompatible at concentrations above their minimum bactericidal concentrations, leading to selectivity values that compare well with other microbicidal products.

Selective solid-phase extraction of Ni(II) by an ion-imprinted polymer from water samples

A new ion-imprinted polymer (IIP) material was synthesized by copolymerization of 4-vinylpyridine as monomer, ethyleneglycoldimethacrylate as crosslinking agent and 2,2′-azobis-sobutyronitrile as initiator in the presence of Ni–dithizone complex. The IIP was used as sorbent in a solid-phase extraction column. The effects of sampling volume, elution conditions, sample pH and sample flow rate on the extraction of Ni ions form water samples were studied. The maximum adsorption capacity and the relative selectivity coefficients of imprinted polymer for Ni(II)/Co(II), Ni(II)/Cu(II) and Ni(II)/Cd(II) were calculated. Compared with non-imprinted polymer particles, the IIP had higher selectivity for Ni(II). The relative selectivity factor ( α r) values of Ni(II)/Co(II), Ni(II)/Cu(II) and Ni(II)/Cd(II) were 21.6, 54.3, and 22.7, respectively, which are greater than 1. The relative standard deviation of the five replicate determinations of Ni(II) was 3.4%. The detection limit for 150 mL of sample was 1.6 μg L −1 using flame atomic absorption spectrometry. The developed method was successfully applied to the determination of trace nickel in water samples with satisfactory results.

Water-Soluble Surface-Anchored Gold and Palladium Nanoparticles Stabilized by Exchange of Low Molecular Weight Ligands with Biamphiphilic Triblock Copolymers

A study is presented of the stabilization of gold and palladium nanoparticles (NPs) via a place-exchange reaction. Au and Pd NPs of approximately 3.5 nm were prepared by a conventional method using tetraoctylammonium bromide (TOAB) as the stabilizing agent. The resulting nanoparticles, referred to as Au-TOAB or Pd-TOAB, were later used as templates for the replacement of TOAB ligand with poly(ethylene oxide)- b-polystyrene- b-poly(4-vinylpyridine) (PEO- b-PS- b-P4VP) triblock copolymer. This biamphiphilic triblock copolymer was synthesized by atom transfer radical polymerization (ATRP) with control over the molecular weight and polydispersity. The place-exchange reaction was mediated through strong coordination forces between the 4-vinylpyridine copolymer and the metal species located on the surface of the nanoparticles. In addition, the displacement of the outgoing low molecular weight TOAB ligands by high molecular weight polymers is an entropy-assisted process and is believed to contribute to stabilization. The prepared complex, polymer-NP, exhibits greatly improved stability over the metal-NP complex in common organic solvents for the triblock copolymer. Self-assembly in water after ligand exchange resulted in micellar structures of about approximately 20 nm (electron microscopy) with the metal NP found located on the surface of the micelles. The stability of the nanoparticles in water was shown to depend greatly on the grafting density of the copolymer, with high stability (more than 6 months) at high grafting density and low stability, accompanied with irreversible agglomeration, at relatively low grafting densities. The surprising location of the metal NP (for both Au and Pd) on the surface of the micelles in water is explained by the fact that, upon self-assembly in THF/water system, the most hydrophobic chains (i.e., PS) undergo self-assembly first at low water content forming the core, followed by the P4VP (whether or not associated with the metal) forming a shell, and finally the PEO forming the corona. In lower metal content assemblies, the P4VP chains located in the shell undergo swelling in an acidic medium causing a substantial increase in micellar corona size, as confirmed by dynamic light scattering measurements. The present study offers a simple approach for the stabilization of various metal nanoparticles of catalytic interest, using a unique polymeric support that can be dispersed in organic solvents as well as aqueous solutions.