Copolymers Of N-vinylpyrrolidone Research Articles

Research and Application of Thermally Activated Gel for Control of Lost Circulations

Summary Thermally activated gel (TAG) for control of lost circulations was evaluated, which is based on acrylamide (AM) and N-vinylpyrrolidone (NVP) copolymers crosslinked by polyethyleneimine (PEI). Viscoelasticity, pumpable time, breakthrough pressures, thermal tolerance, and fluid compatibility were tested in this paper, and then field applications in Missan Oilfield, Iraq, were introduced. Laboratory results showed that the strain limit in the linear viscoelastic region was 169% and storage modulus was 870 Pa. Pumpable time of TAG varies with pH values, so pumpable time can be controlled above 60 minutes by adjusting pH values in the temperature ranges of 100°C to 140°C. Breakthrough pressures were tested in 5-mm (inner diameter) and 10-mm (inner diameter) simulating pipes.The breakthrough pressure gradients were 1.172 psi/cm and 1.200 psi/cm at 0.5 mL/min and 1.0 mL/min, respectively, for 10-mm simulating pipes, 1.872 psi/cm and 2.200 psi/cm for 5-mm simulating pipes. TAG maintained morphologies completely and dehydrated slightly after 30 days of aging at 140°C, transformed into a degraded and low-viscosity fluid after 45 days of aging. Tests proved that invasions of inorganic electrolytes, drilling fluid additives, and drilling fluids can lengthen the pumpable time of TAG, so flash settings due to invasions could not occur. Applications in Missan Oilfield verified the performances of TAG mentioned above.

Block Copolymers of Poly(N-Vinyl Pyrrolidone) and Poly(Vinyl Esters) Bearing n-alkyl Side Groups via Reversible Addition-Fragmentation Chain-Transfer Polymerization: Synthesis, Characterization, and Thermal Properties.

Amphiphilic block copolymers of N-vinyl pyrrolidone (NVP) and various vinyl esters (VEs), PNVP-b-PVEs, namely vinyl butyrate (VBu), vinyl decanoate (VDc), and vinyl stearate (VSt), were synthesized through RAFT polymerization techniques. The sequential addition of the monomers methodology was employed starting from the polymerization of NVP followed by the polymerization of the Ves' monomer. The polymerization of NVP was conducted at 60 °C in benzene solution using AIBN as the initiator and O-ethyl S-(phthalimidylmethyl) xanthate as the CTA. The resulting PNVP macro-CTA was further applied for the polymerization of the vinyl ester in dioxane solution at 80 °C using, again, AIBN as the initiator. The block copolymers were characterized through size-exclusion chromatography (SEC) and NMR spectroscopy. The thermal behavior of the copolymers was studied by Differential Scanning Calorimetry (DSC), whereas their thermal stability via Thermogravimetric Analysis (TGA) and Differential Thermogravimetry (DTG).

Comparative study of N-vinyl pyrrolidone and cyclic ketene acetal copolymer degradation under alkaline, enzymatic, or wastewater conditions

The (bio)degradability of cyclic ketene acetal (CKA)-containing polymers is dependent on the polymer structure and degradation conditions. Copolymers of N-vinyl pyrrolidone (NVP), with different CKA comonomers and architectures, were subjected to (bio)degradation under alkaline, enzymatic and wastewater conditions. Grafting CKA-co-NVP moieties onto a poly(ethylene oxide) (PEO) backbone promoted the enzymatic hydrolysis of CKA esters and improved the overall polymer biodegradability. Limited biodegradation was observed for poly(CKA-co-NVP) in the presence of wastewater sludge during an industrial biodegradability test under OECD 301F guidelines. Under less stringent test conditions poly(CKA-co-NVP) achieves small, yet non-negligible biodegradation. Structural analysis of the degradation products shed light into the degradation mechanisms, revealing CKA ester hydrolysis in all cases, while in presence of wastewater sludge, additional CKA end-group oxidation was clearly observed. However, effective amide hydrolysis or pyrrolidone unit biodegradation was not detected, with pyrrolidone-containing segments persisting through the biodegradation test.

Polymeric carriers of vanadyl ions based on copolymers of N-vinylpyrrolidone with vinylimines

In this study, a series of new chelating copolymers containing 20% azomethine groups, poly(N-vinylpyrrolidone-co-vinylsalicylideneimine) (poly[VP-co-VSalI]), poly(N-vinylpyrrolidone-co-vinylpicolinideneimine) (poly[VP-co-VPicI]), poly(N-vinylpyrrolidone-co-vinylpyridoxylideneimine) (poly[VP-co-VPyrI]) with M = 63000 Da and their vanadium(IV) complexes – poly(VP-co-VSalI)-VO, poly(VP-co-VPicI)-VO, poly(VP-co-VPyrI)-VO, were designed and synthesized. These are intended for the delivery and pH-dependent release of vanadium species in the intestine environment. The chelating polymers were obtained from poly(N-vinylpyrrolidone-co-N-vinylamine) (poly[VP-VAm]) by polymer-analogous transformations with the corresponding aldehydes. The vanadium content, determined by ICP-AES and spectrophotometric methods, was 5.36%, 4.99%, and 9.1% of the dry mass for poly(VP-co-VSalI)-VO, poly(VP-co-VPyrI)-VO, and poly(VP-co-VPicI)-VO, respectively. XPS data confirmed that only vanadium(IV) is presented in the complexes. All complexes demonstrated a pH-dependent release of low molecular weight vanadium species, making them promising candidates for the development of vanadium-containing systems for oral administration. These systems protect the main vanadium content in the stomach but can release biologically active ions in the intestine.

Developing Green Sorbents Derived from Natural Materials for Microextraction and Determination of Emerging Contaminants

Developing Green Sorbents Derived from Natural Materials for Microextraction and Determination of Emerging Contaminants

Electrochemical Study of the Antitumor Antibiotic Doxorubicin in Its Free Form and Encapsulated in a Biocompatible Copolymer of N-Vinylpyrrolidone and (di)Methacrylates

Electrochemical Study of the Antitumor Antibiotic Doxorubicin in Its Free Form and Encapsulated in a Biocompatible Copolymer of N-Vinylpyrrolidone and (di)Methacrylates

Amphiphilic block copolymers of poly(N-vinyl pyrrolidone) and poly(isobornyl methacrylate). Synthesis, characterization and micellization behaviour in selective solvents

Block copolymers of N-vinyl pyrrolidone (NVP) and isobornyl methacrylate (IBMA), PIBMA-b-PNVP, were prepared employing the RAFT polymerization technique. IBMA was polymerized first followed by the polymerization of NVP in the presence of a suitable fluoroalcohol to accelerate the crossover reaction. The copolymers were characterized by Size Exclusion Chromatography (SEC) and NMR spectroscopy. The thermal stability of these copolymers was studied via Thermogravimetric Analysis (TGA) and Differential Thermogravimetry (DTG), showing unique characteristics compared to the respective PIBMA and PNVP homopolymers. The micellization behavior was studied in THF, which is a selective solvent for the PIBMA blocks. The corresponding statistical copolymers, PNVP-stat-PIBMA were also examined to elucidate the effect of the macromolecular architecture on the micellar properties. Furthermore, the self-assembly behavior in aqueous solutions was studied for the PIBMA-b-PNVP block copolymers. Water is a selective solvent for the PNVP blocks. Static (SLS) and dynamic light scattering (DLS) were employed to study the micellar assemblies. The encapsulation of the hydrophobic compound curcumin within the micellar core of the micellar structures in aqueous solutions was investigated by UV–Vis spectroscopy and DLS measurements.

Effect of the Formation of Hydrophilic and Hydrophobic-Hydrophilic Associates on the Behavior of Copolymers of N-Vinylpyrrolidone with Methyl Acrylate in Aqueous Solutions.

It has been shown that there exist conditions under which thermosensitive copolymers of N-vinylpyrrolidone with methyl acrylate form hydrophobic-hydrophilic associations, which are unstable dynamic meshes, the bonds in which are continuously broken and created again, and the nature of the formation of such meshes depends significantly on the proportion of the hydrophobic component in the copolymer. It is shown that the interaction of the above copolymers with polyacrylic acid results in the formation of not only classical interpolymer complexes, but also hydrophilic interpolymer associates, which also represent unstable networks existing in a dynamic mode. In such meshes, the molecules of the above copolymers serve as a kind of cross-agent connecting the polyacid molecules. There are also conditions under which such meshes acquire a complex structure, since unstable bonds between macromolecular tangles of both the same and different types take part in their formation. It is shown that the transition from the formation of interpolymer complexes to the formation of hydrophilic interpolymer associates can occur, among other things, due to changes in the acidity or concentration of low-molecular salt in solution.

Solid phase extraction technology combined with UPLC-MS/MS: a method for detecting 20 β-lactamase antibiotics traces in goat's milk.

We develop and validate a method for the rapid determination and identification of 20 β-lactamase antibiotics traces in goat's milk by combining the solid phase extraction technology with ultra-high performance liquid chromatography-tandem mass spectrometry. Goat milk samples were extracted with acetonitrile twice. The supernatant was then extracted and cleaned by solid-phase extraction using divinylbenzene and N-vinylpyrrolidone copolymer. The method was validated, with limits of quantification (LOQs) of 0.3 μg kg-1, specificities of 1/3 LOQ, linearities (R2) > 0.99, recoveries of 80-110%, repeatabilities <10.0%, and intermediate precisions <10.0%. The developed method was suitable for the routine analysis of β-lactamase antibiotics residues in goat's milk and was used to test 76 goat milk samples produced in China.

Effect of synthesis conditions on molecular characteristics of coumarin and N-vinylpyrrolidone copolymers

Radical copolymerization was used to synthesize copolymers of coumarin and N -vinylpyrrolidone with molecular masses and compositions varying over wide limits. Molecular and hydrodynamic characteristics of the prepared copolymers and their dependence on the synthesis conditions were studied by dynamic and static light scattering.

Effect of Synthesis Conditions on Molecular Characteristics of Coumarin and N-Vinylpyrrolidone Copolymers

Effect of Synthesis Conditions on Molecular Characteristics of Coumarin and N-Vinylpyrrolidone Copolymers

Synthesis of water-soluble analogs-polymers of poly-N-vinylpyrolidone grafted with zinc phthalocyanine

The paper describes the synthesis of polymer analogues of N-vinylpyrrolidone with acryloyl chloride functionalized with zinc phthalocyanine, by using the Friedel-Crafts method. The grafting of zinc phthalocyanine to Nvinylpyrrolidone copolymers was carried out at low temperatures (3-5 ⁰C), using the anhydrous AlCl3 catalyst. The purification of the new polymers was carried out by sedimentation in water. The chemical structure of polymer analogues were performed by IR, UV/Vis spectroscopy. The bactericidal properties of the synthesized polymer analogs were studied. The antibacterial activity of grafted copolymers with zinc phthalocyanine was performed „in vitro”, with a series of bactericidal cultures such as S. Aureus, E. Coli, Ps. Aeruginosa and others. It has been shown that the obtained polymer analogs possess relatively high bactericidal activity against some cultures such as Ps. Aeruginosa, Pr. Vulgaris to the action of furacilin or chlorhexidines, used as controls.

Nanoscale systems folic acid—amphiphilic copolymer of N-vinylpyrrolidone with methacrylic acid, branched with triethylene glycol dimethacrylate

Nanoscale systems folic acid—amphiphilic copolymer of N-vinylpyrrolidone with methacrylic acid, branched with triethylene glycol dimethacrylate

Synthesis and Micellization Behavior of Amphiphilic Block Copolymers of Poly(N-vinyl Pyrrolidone) and Poly(Benzyl Methacrylate): Block versus Statistical Copolymers.

Block copolymers of N-vinyl pyrrolidone (NVP) and benzyl methacrylate (BzMA), PNVP-b-PBzMA, were prepared by RAFT polymerization techniques and sequential addition of monomers. The copolymers were characterized by Size Exclusion Chromatography (SEC) and NMR spectroscopy. Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA) and Differential Thermogravimetry (DTG) were employed to study the thermal properties of these copolymers. The micellization behavior in THF, which is a selective solvent for the PBzMA blocks, was examined. For comparison the self-assembly properties of the corresponding statistical copolymers, PNVP-stat-PBzMA, were studied. In addition, the association behavior in aqueous solutions was analyzed for the block copolymers, PNVP-b-PBzMA. In this case, the solvent is selective for the PNVP blocks. Dilute solution viscometry, static (SLS) and dynamic light scattering (DLS) were employed as the tools to investigate the micellar assemblies. The efficient encapsulation of the hydrophobic curcumin within the micellar core of the supramolecular structures in aqueous solutions was demonstrated by UV-Vis spectroscopy and DLS measurements.

Design and Investigation of New Water-Soluble Forms of α-Tocopherol with Antioxidant and Antiglycation Activity Using Amphiphilic Copolymers of N-Vinylpyrrolidone.

Water-soluble forms of α-tocopherol (TP) as an effective antioxidant were obtained by encapsulating it into nanoparticles (NPs) of amphiphilic copolymers of N-vinylpyrrolidone with triethylene glycol dimethacrylate (CPL1-TP) and N-vinylpyrrolidone with hexyl methacrylate and triethylene glycol dimethacrylate (CPL2-TP) synthesized by radical copolymerization in toluene. The hydrodynamic radii of NPs loaded with TP (3.7 wt% per copolymers) were typically ca. 50 or 80 nm depending on copolymer composition, media, and temperature. Characterization of NPs was accomplished by transmission electron microscopy (TEM), IR-, and 1H NMR spectroscopy. Quantum chemical modeling showed that TP molecules are capable to form hydrogen bonds with donor groups of the copolymer units. High antioxidant activity of both obtained forms of TP has been found by the thiobarbituric acid reactive species and chemiluminescence assays. CPL1-TP and CPL2-TP effectively inhibited the process of spontaneous lipid peroxidation as well as α-tocopherol itself. The IC50 values of luminol chemiluminescence inhibition were determined. Antiglycation activity against vesperlysine and pentosidine-like AGEs of TP water-soluble forms was shown. The developed NPs of TP are promising as materials with antioxidant and antiglycation activity and can be used in various biomedical applications.

Statistical Copolymers of N-Vinylpyrrolidone and 2-Chloroethyl Vinyl Ether via Radical RAFT Polymerization: Monomer Reactivity Ratios, Thermal Properties, and Kinetics of Thermal Decomposition of the Statistical Copolymers.

The radical statistical copolymerization of N-vinyl pyrrolidone (NVP) and 2-chloroethyl vinyl ether (CEVE) was conducted using the Reversible Addition-Fragmentation chain Transfer (RAFT) polymerization technique, employing [(O-ethylxanthyl)methyl]benzene (CTA-1) and O-ethyl S-(phthalimidylmethyl) xanthate (CTA-2) as the Chain Transfer Agents (CTAs), leading to P(NVP-stat-CEVE) products. After optimizing copolymerization conditions, monomer reactivity ratios were estimated using various linear graphical methods, as well as the COPOINT program, which was applied in the framework of the terminal model. Structural parameters of the copolymers were obtained by calculating the dyad sequence fractions and the monomers' mean sequence lengths. Thermal properties of the copolymers were studied by Differential Scanning Calorimetry (DSC) and kinetics of their thermal degradation by Thermogravimetric Analysis (TGA) and Differential Thermogravimetry (DTG), applying the isoconversional methodologies of Ozawa-Flynn-Wall (OFW) and Kissinger-Akahira-Sunose (KAS).

Nanoparticles of N-Vinylpyrrolidone Amphiphilic Copolymers and Pheophorbide a as Promising Photosensitizers for Photodynamic Therapy: Design, Properties and In Vitro Phototoxic Activity.

A series of nanoparticles (NPs) with a hydrodynamic radius from 20 to 100 nm in PBS was developed over the solubilization of hydrophobic dye methyl pheophorbide a (chlorin e6 derivative) by amphiphilic copolymers of N-vinylpyrrolidone with (di)methacrylates. Photophysical properties and biological activity of the NPs aqueous solution were studied. It was found that the dye encapsulated in the copolymers is in an aggregated state. However, its aggregation degree decreases sharply, and singlet oxygen quantum yield and the fluorescence signal increase upon the interaction of these NPs with model biological membranes-liposomes or components of a tissue homogenate. The phototoxic effect of NPs in HeLa cells exceeds by 1.5-2 times that of the reference dye chlorin e6 trisodium salt-one of the most effective photosensitizers used in clinical practice. It could be explained by the effective release of the hydrophobic photosensitizer from the NPs into biological structures. The demonstrated approach can be used not only for the encapsulation of hydrophobic photosensitizers for PDT but also for other drugs, and N-vinylpyrrolidone amphiphilic copolymers show promising potential as a modern platform for the design of targeted delivery vehicles.

Dielectric Properties of Graphite Oxide Polymeric Composites Based on N-Vinylpirrolidone Copolymers with Different Topologies

The dielectric properties of graphite oxide composite materials based on a biocompatible branched copolymer of N-vinylpyrrolidone with 1,6-hexanediol dimethacrylate and a cross-linked copolymer of N‑vinylpyrrolidone with triethylene glycol dimethacrylate are studied. High-frequency (9.8 GHz) and low-frequency (25 Hz–1 MHz) measurements of the complex permittivity and electrical conductivity of polymer composites are carried out and their dependences on the polymer matrix topology and formation conditions are analyzed. Copolymers and composites based on them are characterized by IR, UV, and visible spectroscopy, dynamic light scattering, and the surface morphology of nanocomposite polymer matrices is characterized by optical microscopy. It is shown that the proposed electrophysical approach makes it possible to additionally characterize polymer matrices with carbon nanofillers.

New Nanosized Systems Doxorubicin-Amphiphilic Copolymers of N-Vinylpyrrolidone and (Di)methacrylates with Antitumor Activity.

Nanosized systems of DOX with antitumor activity on the base of micelle-like particles of amphiphilic thermosensitive copolymers of N-vinylpyrrolidone (VP) with triethylene glycol dimethacrylate (TEGDM), and N-vinylpyrrolidone and methacrylic acid (MAA) with TEGDM were explored. They were investigated in aqueous solutions by electron absorption spectroscopy, dynamic light scattering and cyclic voltammetry. Experimental data and quantum-chemical modeling indicated the formation of a hydrogen bond between oxygen-containing groups of monomer units of the copolymers and H-atoms of OH and NH2 groups of DOX; the energies and H-bond lengths in the considered structures were calculated. A simulation of TDDFT spectra of DOX and its complexes with the VP and TEGDM units was carried out. Electrochemical studies in PBS have demonstrated that the oxidation of encapsulated DOX appeared to be easier than that of the free one, and its reduction was somewhat more difficult. The cytotoxicity of VP-TEGDM copolymer compositions containing 1, 5 and 15 wt% DOX was studied in vitro on HeLa cells, and the values of IC50 doses were determined at 24 and 72 h of exposure. The copolymer compositions containing 5 and 15 wt% DOX accumulated actively in cell nuclei and did not cause visual changes in cell morphology.

A Simple, Efficient, Eco-Friendly Sample Preparation Procedure for the Simultaneous Determination of Hormones in Meat and Fish Products by Gas Chromatography-Mass Spectrometry.

Food safety can be severely compromised by the presence of chemical contaminants. This has raised a pressing need to develop efficient analytical methods for their determination at very low levels in complex food matrices. In this manuscript, we developed a simple, sensitive, fast, green analytical method for the determination of thirteen natural and synthetic hormones from different families including progestogens, estrogens and androgens in meat and fish products. The method involves direct extraction with a (9:1) acetonitrile–water mixture and subsequent purification of the extract by semi-automated solid-phase extraction on a sorbent column (hydrophilic–lipophilic copolymer of N-vinylpyrrolidone and divinylbenzene). This treatment enriches samples with the target compounds while removing proteins, lipids and other potential interferences from their matrix for the accurate determination of the analytes by gas chromatography–mass spectrometry, all within 15 min. The proposed method exhibits good linearity (r ≥ 0.996), low limits of detection (0.4–15 ng/kg), acceptable recoveries (90–105%) and relative standard deviations (≤7%); in addition, it is scarcely subject to matrix effects (1–20%). The method was successfully used to determine natural and synthetic hormones in meat and fish products from Spain, Portugal, Italy, Germany, Greece, Norway, Morocco and the USA. The analytes were found at especially high levels (30–1900 ng/kg) in mussels, beef and pork.