Synthesis and characterization of Pd-poly(N-vinyl-2-pyrrolidone)/KIT-5 nanocomposite as a polymer–inorganic hybrid catalyst for the Suzuki–Miyaura cross-coupling reaction

Composite poly(N-vinyl-2-pyrrolidone)/KIT-5 (PVP/KIT-5) was prepared by in situ polymerization method and used as a support for palladium nanoparticles obtained through the reduction of Pd(OAc)₂ by hydrazine hydrate. The physical and chemical properties of the catalyst were investigated by XRD, FT-IR, UV–vis, TG, BET, SEM, and TEM techniques. The catalytic performance of this novel heterogeneous catalyst was determined for the Suzuki–Miyaura cross-coupling reaction between aryl halides and phenylboronic acid in the presence of water at room temperature. The stability of the nanocomposite catalyst was excellent and could be reused 8 times without much loss of activity in the Suzuki–Miyaura cross-coupling reaction.     

Preparation and characterization of plasma-polymerized N-vinyl-2-pyrrolidone films

Thin films (< 1 μm) of plasma polymerized N-vinyl-2-pyrrolidone (PPNVP) have been prepared, using an inductively coupled RF glow discharge in a flow-through reactor system. PPNVP films were hydrophilic, smooth, and appeared morphologically homogeneous. The polymer deposition rate was found to increase linearly with NVP flow rate, and to decrease with the distance from the induction coil. ATR–FT–IR spectral studies suggested a highly branched polymer structure and included absorptions at 2150 and 1540 cm^?1 which were unique to the plasma polymer and derived from lactam ring opening/breaking reactions. ESCA studies demonstrated that, under a given set of plasma reaction conditions, the surface composition was consistent throughout the reactor. However, polymer composition was influenced by larger changes in the plasma energy, since the nitrogen content was found to decrease with increasing W/FM. This corresponded to concomitant increases in the advancing water contact angles and to small but reproducible changes in the IR spectrum.     

Poly(N-vinyl-2-pyrrolidone) and 1-Octyl-2-pyrrolidinone Modified Ionic Microemulsions

The influence of the nonionic polymer poly(N-vinyl-2-pyrrolidone) (PVP) in comparison to the surfactant 1-octyl-2-pyrrolidinone (OP) on the phase behavior of the system SDS/pentanol/xylene/water was studied. In both modified systems a strong increase in the water solubilization capacity was found, accompanied by a change in the spontaneous curvature toward zero. In the polymer-modified system an isotropic phase channel is formed with increasing polymer content that connects the L1 and the L2 phase. The lamellar liquid crystalline phase is destabilized in both cases. In the L1 phase the adsorption of PVP at the surface of the microemulsion droplets and the formation of a cluster-like structure is proven by several methods like ¹³C NMR T₁ relaxation time measurments, zeta potential measurements, and rheology. In the L2 phase a modification of the interface of the inverse droplets is detected by a shift in the percolation boundary (conductivity) and ¹³C NMR T₁ relaxation measurements. The formation of a cluster-like structure can be assumed on the basis of our rheological measurements.     

The role of octadecylamine as zirconium phosphate intercalating agent on poly(vinyl alcohol)/poly(N-vinyl-2-pyrrolidone) biodegradable systems

Journal of Thermal Analysis and Calorimetry - Biodegradable ternary systems based on poly(vinyl alcohol)/poly(N-vinyl-2-pyrrolidone)/octadecylamine-containing zirconium phosphate were studied....     

Graft copolymerization of N-vinyl-2-pyrrolidone onto pre-irradiated poly(vinylidene fluoride) powder

Graft copolymerization of N-vinyl-2-pyrrolidone (NVP) onto ⁶⁰Co γ-ray pre-irradiated poly (vinylidene fluoride) (PVDF) powder was investigated to find out the relationship between the degree of grafting (DG) and various factors, including monomer concentration, irradiation dose, reaction time, catalyst and so on. The DG can be calculated by comparing the amount of nitrogen element in the resulting copolymer (PVDF-g-PVP) powder with that in PVP on the basis of element analysis. The presence of PVP in the resulting PVDF powder was confirmed by the comparative studies of pristine PVDF and grafted PVDF powder through Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS), thermo gravimetric analyzer (TGA) and differential scanning calorimetry (DSC), respectively. When the reaction was performed at the monomer concentration of 20% (vol.) and the absorbed dose of 40 kGy for 3 h in water, the max. DG of 17.7% was obtained.     

New photoluminescent copolymers of naphthalene-2,7-diol dimethacrylate and N-vinyl-2-pyrrolidone

Syntheses of the new photoluminescent copolymers: 2,7-(2-hydroxy-3-methacryloyloxypropoxy)naphthalene with N-vinyl-2-pyrrolidone (NVP) are presented. The obtained compound was copolymerised with different ratios of active diluent (NVP). Thermo- and photo-polymerisations of the compositions with use of the initiators: α,α′-azoiso-bis-butyronitrile and 2,2-dimethoxy-2-phenyl-acetophenone were carried out. The following properties were determined: density, polymerisation shrinkage, glass transition temperature, Young’s modulus, hardness and tensile strength. Moreover, the dynamic-mechanical, thermal and photoluminescent properties were studied. These materials may have potential use as luminophores and coatings filtering harmful UV radiation.     

Determination of N-vinyl-2-pyrrolidone and N-methyl-2-pyrrolidone in drugs using polypyrrole-based headspace solid-phase microextraction and gas chromatography-nitrogen-phosphorous detection

A headspace solid-phase microextraction and gas chromatography-nitrogen-phosphorous detection (HS-SPME-GC-NPD) method using polypyrrole (PPy) fibers has been introduced to determine two derivatives of pyrrolidone; N-vinyl-2-pyrrolidone (NVP) and N-methyl-2-pyrrolidone (NMP). Two types of PPy fibers, prepared using organic and aqueous media, were compared in terms of extraction efficiency and thermal stability. It was found that PPy film prepared using organic medium (i.e. acetonitrile) had higher extraction efficiency and more thermal stability compared to the film prepared in aqueous medium. To enhance the sensitivity of HS-SPME, the effects of pH, ionic strength, extraction time, extraction temperature and the headspace volume on the extraction efficiency were optimized. Using the results of this research, high sensitivity and selectivity had been achieved due to the combination of the high extraction efficiency of PPy film prepared in organic medium and the high sensitivity and selectivity of nitrogen-phosphorous detection. Linear range of the analytes was found to be between 1.0 and 1000 μg L⁻¹ with regression coefficients (R²) of 0.998 and 0.997 for NVP and NMP, consequently. Limits of detection (LODs) were 0.074 and 0.081 μg L⁻¹ for NVP and NMP, respectively. Relative standard deviation (R.S.D.) for five replications of analyses was found to be less than 6.0%. In real samples the mean recoveries were 94.81% and 94.15% for NVP and NMP, respectively. The results demonstrated the suitability of the HS-SPME technique for analyzing NVP and NMP in two different pharmaceutical matrices. In addition, the method was used for simultaneous detection of NVP, 2-pyrrolidone (2-Pyr), γ-butyrolactone (GBL) and ethanolamine (EA) compounds.     

Helical polyurethane@attapulgite nanocomposite: Preparation, characterization and study of optical activity

Helical polyurethane@attapulgite (BM-ATT) based on R-1,1′-binaphthyl-2′,2-diol (R-BINOL) composite was prepared after the surface modification of attapulgite (ATT). BM-ATT was characterized by Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HTEM) and vibrational circular dichroism (VCD) spectroscopy. FT-IR and XRD analyses indicate that the helical polyurethane has been successfully grafted onto the surfaces of the modified ATT without destroying the original crystalline structure of ATT. BM-ATT exhibits the rod-like structure by SEM, TEM, and HTEM photographs. BM-ATT displays obvious Cotton effect for some absorbance in VCD spectrum, and its optical activity results from the singlehanded conformation of helical polyurethane.     

Single-chain mechanical property of poly(N-vinyl-2-pyrrolidone) and interaction with small molecules

The single-chain nanomechanical properties of poly(N-vinyl-2-pyrrolidone) (PVPr) and povidone-iodine (PVPr-I2) under different solution conditions have been investigated by using an atomic force microscopy based technique-single-molecule force spectroscopy. The force-extension curve (force curve) of PVPr in water is markedly deviated from that obtained in ethanol or tetrahydrofuran, suggesting a different interaction between PVPr and the solvents. Moreover, we have comparatively studied the force signals of PVPr-I2 and PVPr in an aqueous solution of KI or KI3 and found that only KI3 influences the elastic property of PVPr dramatically. These experimental results indicate that there exists a specific interaction between PVPr and KI3, which is also supported by Fourier transform infrared data. By the integration of the deviated area between the force curve and the modified freely jointed chain fitting curve, we estimate that the energy needed to destroy the interaction between PVPr and water is 5.3 kT and between PVPr and KI3 is 3.6 kT per repeating unit, respectively.     

A new thermoplastic vulcanizate (TPV)/organoclay nanocomposite: Preparation,characterization, and properties

The preparation, characterization, and properties of the new thermoplastic vulcanizate (TPV)/organoclay nanocomposites are reported in this article. The nanocomposites were prepared by the melt intercalation method. The organoclay was first treated with glycidyl methacrylate, which acts as a swelling agent for organoclays, as well as a grafting agent for TPV (in the presence of dicumyl peroxide) during the melt mixing. The nanocomposite was intercalated, as evidenced by X‐ray diffraction. The tensile modulus of the 5% TPV/organoclay nanocomposite was higher than that of the 20% talc‐filled microcomposite. The storage modulus of the nanocomposite was higher than that of the pristine TPV. The most important observation is obtained from dynamic mechanical analysis, which reveals that the glass‐transition temperature of the polypropylene phase of the nanocomposite increases (as compared to virgin TPV), whereas the ethylene–propylene–diene monomer phase remains almost the same. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2900–2908, 2004     

Surfactant--polymer aggregates formed by sodium dodecyl sulfate, poly(N-vinyl-2-pyrrolidone), and poly(ethylene glycol)

The interaction of sodium dodecyl sulfate (SDS) in aqueous solution with poly(N-vinyl-2-pyrrolidone) (M(w) = 55,000 g/mol) in the presence of poly(ethylene glycol) (M(w) = 8000 g/mol) is investigated by electrical conductivity, zeta potential measurements, viscosity measurements, fluorescence spectroscopy, and small-angle X-ray scattering (SAXS). The results indicate that SDS-polymer interaction occurs at low surfactant concentration, and its critical aggregation concentration is fairly dependent on polymer composition. The polymer-supported micelles have average aggregation numbers dependent on surfactant concentration, are highly dissociated when compared with aqueous SDS micelles, and have zeta potentials that increase linearly with the fraction of PVP at constant SDS concentration. The analysis of the SAXS measurements indicated that the PVP/PEG/SDS system forms surface-charged aggregates of a cylindrical shape with an anisometry (length to cross-section dimension ratio) of about 3.0.     

Preirradiation grafting of N-vinyl-2-pyrrolidone onto poly(tetrafluoroethylene) and poly(tetrafluoroethylene-hexafluoropropylene) films

Preirradiation grafting of N-vinylpyrrolidone (NVP) onto poly(tetrafluoroethylene) (PTFE) and poly(tetrafluoroethylene-hexafluoropropylene) (FEP) films was investigated. The influence of grafting parameters such as preirradiation dose, monomer concentration, and grafting temperature on the rate and grafting yield was studied. Different solvents were used for diluting the monomer and it was found that the aqueous monomer solution at a concentration of 80 wt% was suitable for this grafting system. However, the graft polymerization of NVP in benzene terminated within a short time without significant grafting yield. The dependence of the grafting rate on preirradiation dose and monomer concentration was 1.2 and 1.07 order, respectively, for grafting onto PTFE films and 1.1 and 1.2 order, respectively, for grafting onto FEP films. Arrhenius plots for grafting onto PTFE films showed a breaking point at ca. 35°C and the overall activation energies were calculated as 23.6 and 9.0 Kcal/mol below and above 35°C, respectively. For grafting onto FEP films, however, no break was observed in the Arrhenius plots; the overall activation energy was 11.9 Kcal/mol. The swelling behavior and electric resistance of the grafted materials were investigated.     

Binding of benzopurpurin 4B to poly(N-vinyl-2-pyrrolidone): A spectral study on the mechanism of dye binding

The binding mechanism of benzopurpurin 4B to poly(N-vinyl-2-pyrrolidone) was studied by a spectrophotometric absorbance change method at pH 7.1 in 0.05 mol dm^–3 phosphate buffer. The results were analyzed by Scatchard, Hill, and Schwarz methods. The different shapes of the Scatchard plots indicated the varying degrees of cooperativity which depended on the percent saturation of binding sites. The Hill method elucidated the pairwise binding of the dye to polymer at the intermediate saturation and multimolecular binding both at the low and high saturations. The Schwarz method confirmed the interaction between bound dye molecules which led to cooperativity. The difference spectra of the polymer-dye complex evidenced the elucidated binding mechanism.