poly-N-vinyl-2-pyrrolidone Research Articles

Dehalogenation of Aryl Halides Catalyzed by Montmorillonite Immobilized Bimetal Catalyst in Aqueous System

A novel bisupported bimetal catalyst PVP-PdCl 2-FeSO 4/Al-Mont-PEG600 was prepared by immobilization of PVP (poly (N-vinyl-2-pyrrolidone)) supported bimetallic catalyst using alumina pillared inartificial montmorillonite as the carrier. This catalyst has good dehalogenation activity and selectivity to aryl halides— o-chlorotoluene in aqueous system in the presence of phase transfer catalyst (PEG) and sodium formate as hydrogen source. The catalyst also shows good reusability.

Controlling the agglomeration of anisotropic Ru nanoparticles by the microwave–polyol process

A rapid polyol process for the synthesis of ruthenium nanoparticles was developed using microwave irradiation. A colloidal solution of monodispersed anisotropic Ru metal nanoparticles (mean particle size 2–6 nm) with different aspect ratios was obtained first. Particles with different degrees of agglomeration have also been synthesized using monodisperse particles as seeds and PVP (poly- N-vinyl-2-pyrrolidone) as the stabilization reagent. The stabilization mechanisms of different protective reagents were studied by UV–vis spectra. The HRTEM images indicated that dendritic particles formed by controlling agglomeration consisted of single-crystal domains with a random crystalline orientation.

Solubility Parameters of Cross‐Linked Poly(N‐Vinyl‐2‐pyrrolidone‐co‐crotonic Acid) Copolymers Prepared by γ‐Ray‐Induced Polymerization Technique

Poly(N‐vinyl‐2‐pyrrolidone‐co‐crotonic acid) [P(VP/CrA)] copolymers were prepared by irradiating the ternary mixture of VP/CrA and cross‐linking agent ethylene glycol dimethacrylate (EGDMA) in water by γ‐rays at ambient temperature. The solubility parameters of these copolymers were determined by 20 solvents with various solubility parameters in swelling experiments. The solubility parameter of poly(N‐vinyl 2‐pyrrolidone (PVP)) homopolymer was determined to be 32.26 ± 0.09 (MPa)1/2. However, the solubility parameters of P(VP/CrA) networks did not change much with crotonic acid (CrA) content increase in the network.

The effect of the ratio of thiourea to Cd 2+ on the properties of CdS nanoparticles

CdS nanoparticles capped by thiourea and stabilized by PVP (poly N-vinyl-2-pyrrolidone) were prepared using a wet chemical route. The eventual particles size and size distribution can be systematically controlled by adjusting the relative ratios of thiourea to Cd 2+. The nanoparticles were characterized by transmission electron microscopy (TEM), ultraviolet visible (UV–vis) absorption spectra and photoluminescence (PL) spectra. The results show that the higher thiourea/Cd 2+ ratio leads to higher stability, smaller size and narrower size distribution. After the nanoparticles were capped by thiourea, the band emission of CdS nanoparticles can be observed in the PL spectra.

Radiation synthesis of n-vinyl 2-pyrrolidone/acrylonitrile interpenetrating polymer networks and their use in uranium recovery from aqueous systems

Interpenetrating Polymer Networks (IPNs) based on Poly n-vinyl 2-pyrrolidone (PVP) and Acrylonitrile (AN) were prepared by irradiating PVP solutions prepared in AN. PVP/AN mixtures were irradiated by 60Co-γ rays at room temperature at a dose rate of 0.5 kGy/hour. IPNs were characterized by using FT-IR and Thermal Analysis techniques. The chelating adsorbents containing amidoxime groups were prepared by the reaction of these IPNs with hydroxylamine in aqueous NaOH solution at 50°C. These amidoxime containing adsorbents were used in adsorption studies for the recovery of uranium from aqueous systems. The adsorption capacity of an IPN with equivolume fraction of PVP and amidoximated PAN was found to be 750mg UO 2 2+/g dry amidoximated IPN.

Third-Order Optical Nonlinearities of Quantized CdS and Metal Ultrafine Particles Co-Dispersed in Polymer Matrices – Surface Modification Effect

ABSTRACTQuantized CdS particles of about 60 A in diameter were prepared by an organo-sol method in the presence of PVP (poly(N-vinyl-2-pyrrolidone)), and this new method could make the CdS ultrafine particles densely dispersed in PHEMA (poly(2-hydroxyethyl methacrylate)) host films. The values of | x(3) |/α (third-order optical nonlinear susceptibility per unit absorption coefficient) were obtained (2.0 × 10-10 esu· cm at 460 nm and 2.7 × 10-10esu · cm at 470 nm) using a nanosecond DFWM technique. An enhancement of non-linearity was observed for the first time when Ag particles or Ag+ ion were co-dispersed with the CdS particles in small amounts. The addition of 8.57 wt% Ag particles, or 4.28 wt% Ag+ ion in the ratio to CdS made | x(3) |/α enhanced to be 3.9 × 10-10 esu· cm, or 4.1 × 10-10 esu· cm, respectively. The surface modification by the formation of Ag2S on the surface of CdS colloids is believed to be responsible for this enhancement.