Mixture Of Polyvinylpyrrolidone Research Articles

Interaction Study of Anionic Surfactant with Aqueous Non‐Ionic Polymers from Conductivity, Density and Speed of Sound Measurements

AbstractIn the present study, we have investigated in detail the interactions of the anionic surfactant sodium dodecyl sulfate (SDS) with aqueous polyethylene glycol (PEG), polyvinyl pyrrolidone (PVP) and various PEG + PVP mixtures at 293.15, 303.15 and 313.15 K by applying conductivity, density and speed of sound techniques. From experimentally measured data, the critical micelle concentration (CMC) values, standard free energy of micellization (ΔGmo), standard enthalpy of micellization (ΔHmo), standard entropy of micellization (ΔSmo), isentropic compressibilities (κs), apparent molar volumes (ϕv) and apparent molar isentropic compressions (ϕk) of SDS in aqueous polymer mixtures have been calculated. The nature of the process of micellization has been evidenced from the magnitude of ΔGmo, ΔHmo and ΔSmo values. The trends of variations obtained in the various parameters have been explained in terms of the electrostatic as well as hydrophobic interactions pertaining in SDS−PEG/PVP−water systems.

High stability of photoinduced merocyanine in naphthopyran‐doped polyvinylpyrrolidone electrospun nanofibers

AbstractHighly stable merocyanines (MCs) of naphthopyrans based on polyvinylpyrrolidone (PVP) nanofibers have been developed by electrospinning mixtures of PVP and naphthopyran derivatives. The surface and internal features of the electrospun fibers were characterized using scanning electron microscopy and Fourier transform infrared spectroscopy. The naphthopyrans displayed normal photochromic performance in the polymeric fibers and presented high‐stability MC forms. The one‐dimensional structure of the nanofibers and hydrogen bonds between PVP and MC structures of naphthopyran were responsible for the high degree of stability. The absorption intensities of the most highly stable MC form were 77% compared with the initial intensity after fading for three days. © 2014 Society of Chemical Industry

Electrospun water-soluble polymer nanofibers for the dehydration and storage of sensitive reagents

The ability to preserve and deliver reagents remains an obstacle for the successful deployment of self-contained diagnostic microdevices. In this study we investigated the ability of bacteriophage T7 to be encapsulated and preserved in water soluble nanofibers. The bacteriophage T7 was added to mixtures of polyvinylpyrrolidone and water and electrospun onto a grounded plate. Trehalose and magnesium salts were added to the mixtures to determine their effect on the infectivity of the bacteriophage following electrospinning and during storage. The loss of T7 infectivity was determined immediately following electrospinning and during storage using agar overlay plating and plaque counting. The results indicate that the addition of magnesium salts protects the bacteriophage during the relatively violent and high voltage electrospinning process, but is not as effective as a protectant during storage of the dried T7. Conversely, the addition of trehalose into the electrospinning mix has little effect on the electrospinning, but a more significant role as a protectant during storage.

Preceramic polymer‐derived SiOC fibers by electrospinning

ABSTRACTSilicon oxycarbide (SiOC) fibers with different chemical compositions were successfully fabricated by electrospinning a mixture of polyvinylpyrrolidone (PVP) and commercially available polymethylsilsesquioxane (MK) or polymethylphenylsilsesquioxane (H44) preceramic polymers, followed by cross‐linking and pyrolysis at 1000°C in Argon. The influence of the processing procedure (solvent selection, cross‐linking catalyst and additives) on the morphology of the produced fibers was investigated. For the MK/isopropanol system, the introduction of 20 vol% N,N‐dimethylformamide (DMF) enabled to decrease the diameter of the as‐spun fibers from 2.72 ± 0.12 μm to 1.65 ± 0.09 μm. For the H44/DMF systems, beads‐free fibers were obtained by adding 50 vol% choloroform. After pyrolysis, the resultant SiOC fibers derived from MK and H44 resins possessed uniform morphology, with an average diameter of 0.97 ± 0.07 μm and 1.07 ± 0.08 μm, respectively. Due to their different chemical compositions, the MK‐derived and H44‐derived SiOC ceramic fibers could find different potential applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39836.

Electrospinning multi-layered nano-solenoid and reticular micro-tubular structure on a microfiber

Collecting electrospun fibers via rotating collectors has been widely used, however this method is mainly used for obtaining aligned fibers and the radial dimensions of collectors are in macro-scale in order to match the speed of the ejected fiber with that of the collector. As the nanotechnology develops, it is desirable to reduce the collectors into micro/nano-scale and fabricate regular architectures on it. Here, we report a simple and general method to wind electrospun micro/nanofibers made of various materials including polyvinylpyrrolidone (PVP), zinc acetate/PVP composite (ZnAc/PVP) and as-electrospun 0.5Ba(Zr0.2Ti0.8)O3–0.5(Ba0.7Ca0.3)TiO3 (BZT–BCT) (a mixture of PVP and organometallic compounds containing elements Ba, Ca, Zr and Ti, hereafter denoted as as-electrospun BZT–BCT) around a rotating microfiber served as a collector. By adjusting the collector's rotating speed, multi-layered nano-solenoid made of ZnAc/PVP nanofibers or as-electrospun BZT–BCT nanofibers and reticular micro-tubular structures made of as-electrospun BZT–BCT nanofibers were obtained, respectively. These structures have the potential applications in nano-mechanical, nano-electromagnetic devices and tissue engineering.

Fabricating fiber, rice and leaf-shaped TiO2 by tuning the chemistry between TiO2 and the polymer during electrospinning

Electrospinning is a facile technique for the fabrication of nanofibers (one-dimensional, 1D, nanostructures) of metals, metal oxides and polymers on a commercial scale which find applications in the fields of energy (dye-sensitized solar cells, Li-ion batteries, fuel cells, etc.), healthcare, environmental engineering and biotechnology (membranes and filters). While electrospinning polymer solutions results in polymer nanofibers, metal oxide nanofibers (say of TiO2) are made by electrospinning a TiO2 precursor along with a polymer into composite nanofibers and subsequently removing the polymer by a sintering process. However, we have found that the morphology of the electrospun TiO2 depends on the chemical nature of the polymer involved and more precisely the chemical interactions between the polymer and the TiO2 during the sintering process. When the polymer is changed from polyvinyl pyrrolidone (PVP) to polyvinyl acetate (PVAc) to a mixture of PVP and PVAc, the morphology of the TiO2 varies from continuous fibre to rice-shaped to leaf-shaped. The present manuscript explores the chemistry between the TiO2 and the above mentioned polymers which results in the structural anisotropy of the electrospun TiO2. The electrospun metal oxides are useful for energy and environmental applications.

Fabrication of SrTiO3 Nanofibers for Hydrogen Production

ABSTRACTWater-splitting to form hydrogen was examined by using strontium titanate (SrTiO3) nanofibers as photocatalysts. SrTiO3 nanofibers were fabricated by hydrothermal treatment of amorphous titanium dioxide nanofibers, which were electrospun from the mixture of polyvinylpyrrolidone (PVP), titanium(IV) butoxide, and acetylacetone. The hydrothermal treatment involved the reaction of amorphous TiO2 nanofiber template with strontium hydroxide octahydrate (Sr(OH)2·8H2O) for 20 hours at 120 ºC. The product was calcined to form crystalline SrTiO3 nanofibers, which were characterized via Scanning Electron Microscopy (SEM)/Energy Dispersive Spectroscopy (EDS) and tested their photocatalytic activities for the water splitting. The hydrogen production with the fabricated SrTiO3 nanofibers was found to be 6.1 μmol·h-1·g-1 catalyst, which is twice that of commercially available SrTiO3 nanoparticles (3.0 μmol·h-1·g-1 catalyst).

In situ FTIR spectroscopic study of the effect of CO 2 sorption on H-bonding in PEG–PVP mixtures

A study of the H-bonding between poly(ethylene glycol) (PEG) and polyvinylpyrrolidone (PVP) in the presence of supercritical carbon dioxide at various temperatures, pressures, different M w of PEG and PVP and different PEG/PVP ratios is presented. In situ attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy was used to investigate H-bonding by examining changes in the relative intensities and positions of peak maxima of the 2nd derivative ν(C O) bands associated with ‘free’ and H-bonded C O groups. In general, relative intensities of bands associated with H-bonded C O groups decreased upon CO 2 sorption and was accompanied by an increase in intensity of bands associated with ‘free’ C O groups. At the same time, these bands were shifted to higher wavenumbers. These shifts were attributed to the shielding effect of CO 2 molecules on H-bonding interactions between PEG and PVP. The magnitude of the effects of CO 2 shielding generally increased with decreasing polymer M w and increasing CO 2 content. However, upon CO 2 venting the extent of the H-bonding between PEG and PVP reappeared. The extent of H-bonding recovery was greatest for blends with low M w PEG ( M w : 4 × 10 2) and PVP ( M w : 9 × 10 3) and PEG content ≥0.54 wt% under mild conditions of pressure (80 bar) and temperature (35 °C). For the same low M w blends, increasing pressure to 150 bar, or temperature to 50 °C, showed poor H-bond recovery upon CO 2 venting. Overall, it was shown that supercritical CO 2-induced shielding of H-bonding interactions in polymer blends is reversible upon CO 2 venting, and the magnitude of both was influenced by processing conditions and blend composition.

Polymer blends used to prepare nifedipine loaded hollow microspheres for a floating-type oral drug delivery system: In vitro evaluation

The aim of this study was to investigate whether hollow microspheres prepared from polymer blends of polyvinyl pyrrolidone (PVP) and ethyl cellulose (EC) could improve the vitro release behavior of the poorly water-soluble drug nifedipine. Hollow microspheres containing nifedipine were prepared by a solvent diffusion-evaporation method using various ratios of PVP and EC codissolved with drug in ethanol/ether (5:1, v/v). The hollow microspheres could float in release medium for more than 24 h, and floating capacities were not be influenced by mixing PVP. In vitro release profiles of hollow microspheres prepared using EC along showed an initial burst release to some extent, and the cumulative release percentage was less than 55% after 24 h. But, not only the slope but also the shape of the release curves was affected by using mixture of PVP and EC. What's more important, when the ratio (PVP/EC) increased to 1.5:8.5, the cumulative release percentage could be increased to 95.8%. Furthermore, the release rate of microspheres showed a zero order approximate dynamic model and could be expressed by the following equation: Q=3.78t+8.52 (r=0.990). Consequently, hollow microspheres prepared using polymer blends of PVP and EC (1.5:8.5, w/w) could be suitable for floating-type controlled-release delivery systems for the oral administration of nifedipine.

English

Stable aqueous monodispersed silver nanoparticles were synthesised by reducing silver nitrate using various sugars such as glucose, fructose, lactose, and sucrose at 55-60 oC. A mixture of two stabilising agents, polyvinyl pyrrolidone (PVP) of molecular weight (MW 40, 000) and gelatin plays a decisive part in controlling size and shape of superfine silver nanoparticles. Using PVP, better control of particle size was obtained, whereas a mixture of PVP, and gelatin resulted in sea urchin kind of structure. Effects of several processing parameters such as pH, quantities of alkaline solution, reaction time, concentration of stabilising agent, and the metal/dispersant ratio were investigated. The suspensions were stable for at least one week. Silver nanoparticles can be easily collected by centrifugation on mixing with sufficient amount of acetone. Structural characterisation of synthesised silver nanoparticles was carried out by X-ray diffraction (XRD), which shows that the as-synthesised silver nanoparticles are face-centered cubic crystalline. Chemical characterisations of as-synthesized silver nanoparticles were done using inductively-coupled plasma-optical emission spectrometry (ICP-OES) and LECO gas analysers. The optical properties of silver nanoparticles were monitored using UV-Vis spectrophotometer. Role of stabilising agent in protecting the silver nanoparticles was studied using fourier transform infrared spectroscopy (FTIR). Particle size and distribution were characterised using smallangle X-ray scattering (SAXS), zeta particle size analyser (PSA), scanning electron microscopy, and transmission electron microscopy. The average particle size of the as-synthesised silver nanoparticles was 35 nm.Defence Science Journal, 2009, 59(4), pp.447-455, DOI:http://dx.doi.org/10.14429/dsj.59.1545

Effect of chirality on PVP/drug interaction within binary physical mixtures of ibuprofen, ketoprofen, and naproxen: A DSC study

We report on the thermal behavior of freshly prepared binary drug/polymer physical mixtures that contained ibuprofen, ketoprofen, or naproxen as a drug, and polyvinylpyrrolidone (PVP), hydroxyethylcellulose (HEC), or methylcellulose (MC) as excipient. At 6-10 degrees C/min heating rates the DSC detected a sharp, single endotherm that corresponds to the melting of drug. On heating physical mixtures of PVP and racemic ibuprofen or ketoprofen at lower heating rates, another endotherm was registered in front of the original one. To observe the additional endotherm, specific minimal values of the heating rate and of PVP weight fraction were needed; for ibuprofen and ketoprofen they were 1.5 and 2.0 degrees C/min, and 5 and 15% (w/w), respectively. At greater PVP weight fractions the top temperatures, T(mp), of both peaks were reduced almost linearly indicating strong solid-state interfacial reaction between the drug particles and PVP matrix. The additional endotherm was abolished at greater heating rates (2 degrees C/min for ibuprofen, 3 degrees C/min for ketoprofen), by replacing the racemate with respective S+-enantiomer and by replacing PVP with HEC and MC. Hence, the possible inclusion of enantioselective component within the PVP/drug interaction, responsible for the amorphization of physical mixture over storage, is assumed.

Fourier Self-Deconvolution Analysis of Hydrogen Bonding States of Polyvinylpyrrolidone in an Amorphous Sugar Matrix Below and Above the Glass Transition Temperature

ABSTRACT In an amorphous mixture of sugar and polyvinylpyrrolidone (PVP), PVP carbonyl groups form hydrogen bonds with sugar hydroxyl groups, thereby improving the physical stability of the amorphous matrix against a glass-to-rubber transition. Herein, Fourier self-deconvolved IR bands due to the C=O stretching vibration of PVP in sugar–PVP mixtures were analyzed. The C=O groups in sugar–PVP mixtures generally had four vibrational states, corresponding with free and hydrogen-bonded C=O in three different modes. Changes in these vibrational states induced by increasing the temperature were compared among various sugar–PVP mixtures. Formation and thermal disruption characteristics of different modes of sugar–PVP hydrogen bondings are discussed.

Characteristics of hydrogen bond formation between sugar and polymer in freeze‐dried mixtures under different rehumidification conditions and its impact on the glass transition temperature

The characteristics of hydrogen bond formation between trehalose and polyvinylpyrrolidone (PVP) in amorphous mixtures at different hydration states were quantitatively investigated. Amorphous trehalose-PVP mixtures were prepared by freeze-drying and equilibrated at different relative humidities (RH). Infrared (IR) spectra of the trehalose-PVP mixtures were obtained by Fourier transform IR spectroscopy,(FTIR) and the IR band corresponding to C=O groups of PVP was deconvolved into the component bands responsible for C=O groups that were free and restricted by hydrogen bonds, to estimate the degree of the trehalose-PVP interactions. The FTIR analysis indicated that approximately 80% of the C=O groups of PVP formed hydrogen bonds with trehalose in the presence of more than 3 g of trehalose per gramme of PVP, independent of the RH. IR analysis of the O--H stretching vibration of the sugar demonstrated that the presence of PVP lead to an increase in the free hydroxyl groups of trehalose that did not form hydrogen bonds at RH 0%. On the other hand, the water sorption behavior of the trehalose-PVP mixtures suggested that rehumidification diminished the effect of PVP on increasing the free OH groups. Thus a peculiar relationship may exist between Tg, RH and the composition of the mixture: The presence of PVP increased Tg at RHs 0 and above 23% but decreased Tg at 11%.

The growth mechanism of ZnO single-crystal nanorods synthesized by polymer complexing with zinc salts

The growth mechanism of single-crystal ZnO nanorods synthesized by the method of polymer complexing with zinc salts is investigated. The annealing temperature is controlled at about the decomposition temperature of dihydrate zinc acetate (Zn(O2CCH3)2·2H2O) of 573 K. By changing the annealing time, the ZnO nanostructures can be modified from nanoparticles to nanorods. As a result, the formation of single-crystal ZnO nanorods can be observed. Through investigating the Fourier transform infrared spectra of (a) polyvinyl pyrrolidone (PVP), (b) Zn(O2CCH3)2·2H2O and (c) the mixture of PVP and Zn(O2CCH3)2(H2O)2, the interaction between PVP and Zn(O2CCH3)2·2H2O can be observed. PVP plays an important role in the growth of the single-crystal ZnO nanorods. We analyze the growth process of ZnO nanorods by observing their TEM images at different moments. Consequently, our results indicate that the single-crystal ZnO nanorods were formed by self-assembling the ZnO nanoparticles.

Interactions between polyvinylpyrrolidone, sodium dodecylsulfate and nonylphenol ethoxylate in solution and on polystyrene particles

Mixtures of polyvinylpyrrolidone (PVP), nonylphenol ethoxylate with, on the average, 84 oxyethylene units (NP100) and sodium dodecylsulfate (SDS) in solution and on polystyrene particles are discussed in terms of various types of interaction according to their mutual affinities. The mixtures in solution were analyzed by means of NMR and static surface tension, which showed that the combination of SDS with PVP agreed well with the classical model with surfactant aggregates along the polymer chain. In the mixture with the nonionic surfactant NP100 and the anionic surfactant SDS, mixed micelles were formed with a strong attraction parameter β = −5.1. Evidence of SDS encapsulation in the NP100 micelle was obtained from NMR diffusometry data where the long and short residence times of SDS in the mixed micelle were estimated to be τ A = 2.19 s and τ B = 0.15 s, respectively. No interaction was found in a mixture between NP100 and PVP in solution. Upon adsorption of these component mixtures to a polystyrene surface, it was shown that complexes formed in solution also dominated at the surface. This applied both for the mixtures of SDS–PVP and of SDS–NP100, with the exception that the mixed micelles of SDS–NP100 seemed to have higher affinity than PVP to the surface. This was considered a result of the nonylphenol group in NP100. For the mixture of NP100 and PVP, the NP100 had a higher affinity to the surface than PVP, though both components were able to co-exist on the surface. Finally, as SDS, NP100 and PVP were adsorbed simultaneously, all three components seemed to adsorb, with a surface complex including SDS with, probably, both NP100 and PVP. In this three-component mixture a preferential adsorption of SDS and NP100 seemed to exist.

Morphological control of calcium carbonate crystals by polyvinylpyrrolidone and sodium dodecyl benzene sulfonate

The crystallization of calcium carbonate was conducted by the reaction of sodium carbonate with calcium chloride in the presence of polyvinylpyrrolidone (PVP), sodium dodecylbenzene sulfonate (SDBS), or the mixture of PVP and SDBS, respectively. The morphology and polymorphism of these CaCO 3 crystals were characterized with scanning electron microscopy (SEM) and powder X-ray diffraction (XRD). The results showed that the organic additives and their self-assemblies turn out to be important factors to affect the crystallization habit of CaCO 3. In particular, the controlling effect on the morphology depends upon not only the total concentration of PVP and SDBS, but also the relative concentration ratio of PVP to SDBS.

Quantitative aspects of the storage of bone marrow cells for transplantation

Quantitative studies are presented of the effect of different storage techniques on mouse and monkey bone marrow cell suspensions. The ability to produce 30-day survival in lethally irradiated hosts was used as an endpoint. The following results were obtained: (1) Optimal protection of mouse bone marrow cell suspensions was found after addition of 10% polyvinylpyrrolidone (PVP) and with the combinations 10% PVP, 10% glycerol and 10% PVP, 10% dimethyl-sulphoxide (DMSO). For isologous mouse bone marrow optimal storage efficiency approximates 100%, for foetal mouse liver cells 40%. (2) For autologous monkey bone marrow storage methods based on the addition of glycerol or DMSO were found to be ineffective. Poor protection was afforded by addition of 10% PVP alone or by a 10% PVP, 10% DMSO mixture. Optimal preservation during storage (up to 50% effectiveness) was found for monkey bone marrow with a 10% glycerol, 10% PVP mixture. It is concluded that although species differences in storage effectiveness preclude dependable recommendations for storage of human bone marrow, a careful trial of the glycerol–PVP combination in man seems indicated.

Comparison between polyvinylpyrrolidone and silica nanoparticles as carriers for indomethacin in a solid state dispersion

States of interaction between indomethacin (IM) and polyvinylpyrrolidone (PVP) in an amorphous solid dispersion prepared by co-grinding were compared with those between IM and silica nanoparticles. Changes in the carbon chemical states of the solid dispersions were evaluated based on the chemical shift in the 13C-CP/MAS-NMR. Hydrogen bonds between the amide carbonyl of PVP particles and the carboxyl groups of IM molecules were formed by co-grinding. Despite the wide difference in carrier properties, the apparent equilibrium solubility (AES) of IM in the ground IM–PVP mixture was predicted by solid state NMR on the basis of the relationship previously established for IM with SiO 2. This indicates that AES is affected solely by the state of IM, irrespective of the carrier species, and despite carrier-dependent chemical interactions.

A study on specific optic impedance of materials

The optic impedance Z of a medium for the propagation of electromagnetic waves is deduced from the definition of wave impedance. A new optical parameter Zo called “specific optic impedance” is defined. The temperature dependence of Zo is examined and an exponential relationship between specific optic impedances at two different temperatures has been derived. The validity of the new relationship is established using the published data on ethyl acetate, cyclohexane, benzene, and a binary mixture of polyvinyl pyrrolidone in N,N-dimethyl formamide solutions from the literature.

Rotational diffusion of rhodamine 6G depends on structural features of water and polyvinyl pyrrolidone mixtures

Rotational diffusion of rhodamine 6G has been measured in an aqueous solution of polyvinyl pyrrolidone by the time-correlated single photon counting method. The rotational relaxation times do not scale linearly with viscosity when the solvent composition is changed at a constant temperature. The change in relaxation time with composition is interpreted in terms of an associated complex formation in the polymer solution system.