Copolymers Of N-vinylpyrrolidone Research Articles

Radical-initiated copolymers of N-vinyl pyrrolidone and N-acryloxy succinimide: kinetic and microstructure studies

Abstract Kinetics of solution (co)polymerization of N-vinyl pyrrolidone (NVP, or V) and N-acryloxy succinimide (NAS, or A) have been investigated at 60°C in N, N-dimethylformamide with 4,4′-azobis(4-cyanopentanoic acid) as initiator. First, the k p √k i value for homopolymerization of A monomer was estimated as 0.87 10.5 mol−0.5 s−0.5. The comonomer feed composition was observed to have a strong effect on the overall copolymerization rate. Reactivity ratios of the binary system were determined to be rNAS = 0.27 ± 0.04 and rNVP = 0.01 ± 0.01, indicating a strong alternating tendency in the formed copolymer. Copolymers were then characterized as regards to composition (by ultraviolet spectrophotometry) and monomer sequence distribution (by 13C nuclear magnetic resonance spectroscopy). The presence of a small fraction of VVA triads was clearly evidenced which was not expected from simulation based on a terminal kinetic model; the occurrence of a more complex model has been discussed.

Preparation of conjugates between oligonucleotides and N-vinylpyrrolidone/N-acryloxysuccinimide copolymers and applications in nucleic acid assays to improve sensitivity.

A simple approach has been developed to prepare conjugates between oligodeoxyribonucleotides (ODNs) and linear copolymers of N-vinylpyrrolidone (NVP)/N-acryloxysuccinimide (NAS). These conjugates were of higher than expected molecular weight, as determined by light scattering. Side reactions between amino groups on heterocyclic bases, especially of cytosine, are proposed to explain the formation of aggregates. ODN-NVP/NAS conjugates used in both capture and detection steps in sandwich hybridization increased assay sensitivity. Sensitivity to 10(7) DNA molecules/mL was reached for a 2.3 kb PCR fragment of hepatitis B virus (HBV) genomic DNA.

Studies on Copolymerization of Acrylamide andN-Vinylpyrrolidone

Abstract Copolymers of acrylamide and N-vinylpyrrolidone were prepared using different techniques, viz., solution, precipitation, and inverse emulsion. Xylene was used as a continuous medium and sorbitane monooleate as a surfactant for the inverse emulsion technique. Acetone was used as a solvent in the precipitation technique. The initiator used in all the reactions was 2,2-azobis(2-amidinopropane)dihydrochloride. C, H, and N elemental analysis was used to determine the compositions of the copolymers formed. Reactivity ratios as determined by the Fineman and Ross method were found to be 0.61 and 0.05 for acrylamide and n-vinylpyrrolidone, respectively. Intrinsic viscosity measurements were made at temperatures ranging from 16 to 75°C.

BOP: Biocompatible osteoconductive polymer: An experimental approach

BOP (biocompatible osteoconductive polymer) is a material proposed for osteosyntheses and for filling of bone defects in orthopaedics, neurosurgery and stomatology. It is a composite made of a copolymer of N-vinylpyrrolidone and methylmethacrylate, of polyamide-6 fibers and of calcium gluconate. The histological investigation includes the study of 30 intact rabbit femurs instrumented with a BOP rod, as well as the study of organs of the reticuloendothelial system. The currently available results show the absence of toxicity on hematopoietic tissue. Zones of osteoblastic activity surround the rods, coupled with an osteoclastic reaction which may result in the partial fragmentation of the polyamide fibers and its incorporation in the newly formed bone. We also observed the encapsulation of the material. The biomechanical approach investigated the mechanical properties of the material in bending and in shear. The radiological aspects of the investigation consisted of computerized axial tomography of the implanted femurs to measure density at the bone-implant interface.

Biocompatible hydrogels of controlled hydrophobicity from copolymers of N-vinyl-2-pyrrolidone and furfuryl methacrylate

Biocompatible copolymers of N-vinylpyrrolidone (P) and furfuryl methacrylate (F) were prepared by free radical polymerization in N, N-dimethylformamide solution at 50°C, using 2,2′-azobisisobutyronitrile as initiator, at low and high conversion. The microstructure of copolymers prepared at low conversion was determined from the composition data by the application of statistical relationships, considering the terminal copolymerization model of Mayo-Lewis, whereas for high conversion copolymers the noticeable difference between the reactivity of F and P was taken into consideration. The swelling behaviour of films prepared from solutions of copolymers with different composition was followed gravimetrically and the diffusion of water was analysed on the basis of the stress relaxation model of copolymer chains. The results obtained are in good agreement with second-order diffusion kinetics, showing that the hydrophilic character of the films is controlled mainly by the content of P in the copolymer systems and the distribution of comonomeric units along the copolymer systems.

The role of the charge-transfer complex during the copolymerization of N-vinylpyrrolidone and maleic anhydride

A attempt is made to prove the possibility of synthesizing copolymers of N-vinylpyrrolidone (VP) and maleic anhydride (MA) with a kinetically regulated structure of the macromolecule. The influence of the charge-transfer complex (CTC), formed from VP and MA, on the dominating tendency toward alternating copolymerization of the two comonomers is studied

Free radical copolymerization of furfuryl methacrylate and N-vinylpyrrolidone

Copolymers of furfuryl methacrylate (F) and N-vinylpyrrolidone (P) were prepared by free radical polymerization in N, N-dimethylformamide solution at 50°C, using 2,2′-azobisisobutyronitrile as initiator. The reactivity ratios of both monomers were calculated according to the general copolymerization equation using the Fineman-Ross and Kelen-Tüdös linearization methods, as well as the Tidwell and Mortimer non-linear least-squares treatment. The reactivity ratios obtained were r F = 3.92 and r P = 0.004. The microstructure of the copolymer chains is described on the basis of first-order Markov statistics, and the copolymer glass transition temperatures ( T gs) were determined calorimetrically. The variation of T g with copolymer composition is discussed according to modern methods, considering the sequence distribution of monomeric units along the copolymer chains. Also the T g of the corresponding homopolymers was determined giving the values T g(F) = 392 K and T g(P) = 358 K, whereas the T g of the corresponding alternating diad has an average value of T gFP = 347 K.

Biochemical and physico-chemical aspects of biomaterials calcification

Intrinsic tissue calcification mainly results from increased penetration of plasma proteins into the leaflets of bioprosthetic cardiac valves. The loss of activity of natural calcification inhibitors changes tissue properties and promotes pathological processes. N-vinylpyrrolidone, 3-amino-1,1-hydroxypropylendiphosphonic acid, O, O-diethylvinylphosphonates and antiaggregant (acryloilsalicylic acid) were used to decrease porosity and prevent calcification, γ-radiation and glutaraldehyde were used to immobilize these agents. Tissue calcification was studied using subcutaneous implantation of the samples in young rats. The study indicates that the copolymerization of N-vinylpyrrolidone, O, O-diethylvinylphosphonates and acryloilsalicylic acid decreases calcium and phosphorous accumulation during in vivo experiments.

Preparation and photochemical characteristics of the copolymer pendant tris(2,2′-bipyridine)ruthenium- mercury [Ru(bpy) 32+ ·Hg 2Cl 62−] complex

A water-insoluble copolymer pendant ruthenium-mercury complex (poly-Ru(bpy) 2+ 3 · [Hg 2Cl 6] 2−) (denoted poly-Ru-Hg) was prepared from a water-soluble Ru(bpy) 2+ 3 pendant complex of the copolymer of N-vinylpyrrolidone and 4-methyl-4′-methyl-2,2′ -bipyridine (denoted poly-Ru). The poly-Ru-Hg complex was characterized by IR, visible absorption and emission spectroscopies and emission decay measurements. The solubility and excited state lifetime both in dimethylformamide (DMF) solution and film state were quite different from those of the low molecular Ru-Hg complex reported before. The emission from the excited poly-Ru-Hg was much longer than that from poly-Ru in DMF solution while, in a film state, it had a shorter lifetime that the poly-Ru. The quenching of the excited ruthenium complexes by oxygen was studied. The quenching of the excited poly-Ru-Hg by oxygen was prohibited probably because of the cluster nature of the complex.

Preparation of conjugates of peptides imitating part of the antigen-determinant section of protein VP1 of foot-and-mouth disease virus A12 with various supports

The preparation of conjugates of peptides 143–148, 153–159, 149–159, 146–159, and 143–159, imitating a section of a protein of the foot-and-mouth disease (FMD) virus of type A12, with bovine serum albumin, with. a copolymer of N-vinylpyrrolidone with acrylic acid, and with a copolymer of N-vinylpyrrolidone with maleic anhydride is described. The dependence of the degree of conjugation on various factors is discussed.

Study of the structure of streptokinase conjugates with a hydrophilic vinylpyrrolidone copolymer

The modification of streptokinase by a synthetic N-vinylpyrrolidone copolymer leads to formation of conjugates varying in structures according to the proportions of the components in the reaction medium. Based on data obtained from spectrophotometry, as well as sedimentation and diffusion analyses, it is shown that in the presence of excess protein in the reaction medium, formation of the main chain takes place via the copolymer associated with several protein globules. Under conditions of excess modifier copolymer, either single-site and/or multiple-site bonding is possible for the protein backbone, depending on the molecular weight of the copolymer. One of the models for the conjugates obtained in this manner has been corroborated by small-angle X-ray scattering data. CD spectral analyses has been performed in order to demonstrate that covalent modification does not alter the secondary structure of streptokinase in the conjugate whereas the tertiary structure undergoes local changes in conformation.

Metal complexes of polymers with amino acid residues. formation, stability and controlled biological activity

Copolymers of N-vinylpyrrolidone and allyl glycidyl ether, modified in the side chain by residues of glycine, β-alanine, γ-aminobutyric acid and ϵ-aminocaproic acid, have been synthesized. The structure and stability of the metal complexes of the copolymers have been investigated by ESR spectroscopy and potentiometric titration methods. It has been found that copolymers with glycine and β-alanine residues co-ordinate metal ions through the oxygen and nitrogen atoms of the amino acid residues; copolymers with γ-aminobutyric and ϵ-aminocaproic acid residues form metal carboxylate complexes. The stability of the polymer-metal complexes depends on the nature of the amino acid residue and decreases in the following order: glycine >; β-alanine >;γ-aminobutyric acid >;ϵ-aminocaproic acid derivatives. The acute toxicity and haemopoiesis-stimulating activity of copolymers and their complexes with cobalt have been taken as evidence of the biological activity of the polymer-metal complexes. It has been shown that the biological properties of polymermetal complexes can be controlled by regulating their stability and structure. Thus, the use of polymers as ligands for creation of polymer-metal complexes is a fruitful means of producing new biologically active compounds affording controlled release of bioactive metals.

Copolymerization of N-vinylpyrrolidone with N,N-dimethyl-N,N-diallylammonium chloride

The possibility of synthesizing copolymers of N,N-dimethyl-N,N-diallylammonium chloride (DMDAAC) and N- vinylpyrrolidone (VP) was demonstrated and the features of radical copolymerization of these monomers in aqueous and alcohol media were investigated. The optimum conditions of conducting the reaction were determined and the kinetic features of the copolymerization reaction in the region of low degrees of conversion, for which the usual order mechanisms for radical polymerization are preserved, were investigated. The dependence of the initial rate of co polymerization on the composition of the starting mixture of comonomers is nonlinear, and the rate of copolymerization decreases significantly as the concentration of DMDAAC in the starting mixture increases. The composition of copolymers formed was studied and the copolymerization constants r1 ef=r2 ef=1 were calculated, i.e., the system is azeotropic, which is also detected for significant degrees of conversion.

Effect of electrostatic and hydrophobic interactions between comb-like polycations and lipids on the change in permeability of lipids at different pH values

The effect of homologous comb-like polycations, copolymers of N-vinylpyrrolidone and N-vinylalkylamines on the permeability of negatively charged dipalmitoylphospatidylcholine liposomes from dipalmitoylphosphatidylcholine containing dipalmitoylphosphatide acid are studied at various solution pH values. The maximum increase in liposome permeability for the 6-carboxy-fluorescein and calceine markers is observed with the copolymer of N-vinyloctylamine over a narrow pH range close to 7.0. The peak-like increase in the permeability of liposomes in a neutral media in regions of neutral pH requires a balance of the electrostatic and hydrophobic interactions between the polycations and the lipid double layer. An increase in the contribution of one of these interactions results in a loss of the significant, and peak-like change in permeability of liposomes with change in pH.

ESR study of copper complexes of copolymers of N-vinylpyrrolidone with amino acid residues

Complex formation in aqueous solution between copper(II) ions and copolymers of N-vinylpyrrolidone with amino acid residues containing glycine, β-alanine, γ-aminobutyric acid, and ε-aminocaproic acid residues are studied by ESR spectroscopy. The composition, structure, and stability of the polymeric metal complexes depend on the nature of the amino acid residues in the copolymer. The character of the bond in the metal-ligand system is evaluated.

Oxidation of Hydroquinone By (N-Vinylpyrrolidone)-(4-Vinylpyridine) Block and Graft Copolymers

ABSTRACT A-B Type block copolymer of N-vinylpyrrolidone (NVP) and 4-vinylpyridine (VPy) [poly(NVP-b-VPy) and graft copolymers of VPy onto copolymers of NVP with 4-vinylbenzyl N,N-diethyldithiocarbamate (VBDC) [poly(NVP-g-VPy) were synthesized by the iniferter method. the compatibility between NVP and VPy units in the copolymers was evaluated from the glass transition temperature of these copolymers. Hydroquinone was then oxidized by the synthesized NVP-VPy copolymers-Cu(II) complex catalysts. the influence of the distribution of each monomer unit in copolymers on the catalytic activity was studied by comparing the activity of these copolymers. the catalytic activity of these copolymers increased in the order: NVP-VPy blend polymer, poly(NVP-b-VPy), poly(NVP-g-VPy), random copolymer [poly(NVP-ran-VPy)]. This order parallels the compatibility between NVP units and VPy units in these copolymers.

Evaluation of polyvinyl alcohol hydrogel as a soft contact lens material

We prepared a transparent polyvinyl alcohol (PVA) hydrogel from a PVA solution in a mixed solvent consisting of water and a water-miscible organic solvent by cooling. The physical properties of the hydrogel were evaluated in various mixed solvents and compared with those of commercially available soft contact lens materials, such as polyhydroxyethyl methacrylate (PHEMA) and copolymers of methylmethycrylate (MMA) and N-vinyl pyrrolidone (N-VP). The PVA hydrogel showed higher tensile strength and elongation before breaking than did the other materials. Also, the PVA hydrogel was comparable in its high water content and its oxygen permeability with the MMA/VP copolymers. The protein adsorption of the PVA hydrogel was much lower than that of the other materials. Soft contact lenses of PVA hydrogel were applied to rabbit eyes for 12 weeks. The effects of the lenses on the cornea were studied by biomicroscopy, ultrasonic pachymetry, and histopathologic examination. No abnormal findings were noted, suggesting that the PVA hydrogel may be promising as a new material for use in soft contact lenses.

Some properties of siloxanyl methacrylate/ N-vinyl pyrrolidone copolymers produced by gamma-irradiation

Crosslinked homopolymers of methacryloxymethylpentamethyldisiloxane (MMS) and N-vinyl-2-pyrrolidone (VP) have been produced by α-irradiation of the monomers in the absence of a crosslinking agent. Similarly, crosslinked copolymeric xerogels were obtained from MMS/VP mixtures. High conversion was attained with the dose used, 2 Mrad (20 kGy) at a fixed dose rate of 0.01 Mrad/h (100 Gy/h). On decreasing the dose rate there was no evidence for proliferous polymerization or popcorn formation (noted previously for the n-butylacrylate/VP system). The homopolymers were optically clear, but the copolymers displayed translucency, haziness or opacity. Hydrogels and organogels were obtained by swelling the copolymers in water and toluene respectively. The influence of copolymer composition and concentration of added hexafunctional crosslinking agent on (i) the optical appearance of xerogels, hydrogels and organogels, (ii) the equilibrium solvent content of swollen gels, (iii) sol fractions have been noted and discussed.

Kinetics of diffusion-controlled release of drugs from polymer matrices

Simultaneous diffusion of the solvent and the drug has been investigated in ternary systems consisting of a N-vinylpyrrolidone copolymer, water and dioxidine. A mathematical model of transport in these systems has been developed and confirmed by experiments. An anomalous mechanism of sorption of water in the copolymers has been established, where the kinetics of the process depends strongly on both the hydrophilicity of the polymer and the drug concentration. The mechanism of drug release depends on the extent of hydrophilicity of the polymer matrix. Physico-chemical parameters characterizing the drug release have been found for all investigated systems. The obtained results explain the fundamental kinetic laws that govern the behaviour of the system polymer-solvent-drug and point to some practical recommendations.

Antisilicotic activity of fractions of the copolymer of ethylene glycol vinyl glycidyl ether and N-vinylpyrrolidone

Antisilicotic activity of fractions of the copolymer of ethylene glycol vinyl glycidyl ether and N-vinylpyrrolidone