Polyvinylpyrrolidone Nanocomposites Research Articles

Resistive switching behavior of the memristor based on WS2 nanosheets and polyvinylpyrrolidone nanocomposites

Ag/tungsten disulfide (WS2)–polyvinylpyrrolidone (PVP)/Cu memristors based on monolayer WS2 nanosheets and polyvinylpyrrolidone (PVP) nanocomposites were fabricated, and the influence of PVP content on the switching behaviors was investigated. The results indicate that the WS2–PVP based memristors show write-once read-many times (WORM) memory behavior. Remarkable resistive switching results such as a low operating voltage (VSET < 1 V), a high switching ratio (>103), good endurance (>100 cycles), and data retention time (>200 s) are obtained. With the increase in the PVP content, the device VSET gradually increases, and the switching ratio first slightly increases and then remarkably decreases. The double logarithm I–V curves verify that the switching mechanism of the devices is the trap-controlled space charge limited current mechanism, which is explained with the energy band diagram.

Vortex assisted dispersive solid phase extraction of thallium followed by electrothermal atomic absorption spectrometry, Adsorption mechanism and soft computing algorithm prediction

ABSTRACT Vortex-assisted dispersive solid-phase extraction technique was used as a rapid and efficient method for preconcentration of ultra-trace levels of total thallium (Tl) followed by electrothermal atomic absorption spectrometry. Graphene oxide-modified polyvinylpyrrolidone nanocomposite was prepared as an adsorbent and characterised by the Fourier transform infrared spectrometry, field emission-scanning electron microscopy, energy-dispersive X-ray spectroscopy , and X-ray diffraction spectroscopy. To find the optimum conditions for extraction of ultra-trace levels of Tl (ӀӀӀ), the response surface methodology based on central composite design was used. Based on the results, pH = 6.6, amounts of adsorbent = 7.7 mg, extraction time = 27 min and desorption time = 5 min provide maximum extraction recovery for Tl (ӀӀӀ). Under the optimum conditions, the calibration curve was linear in the range of 0.08–1.5 µg L−1 Tl (ӀӀӀ) with the R 2 value of 0.9985. The relative standard deviation was 4.0% (n = 7) and the detection limit was 0.019 µg L−1 (n = 8). Also, the enrichment factor which could be calculated from the slope of the calibration curve after preconcentration step to that without preconcentration was 95.8. To understand the adsorption mechanism, two-parameter and three-parameter adsorption isotherms were studied, and the obtained results show that the adsorption of Tl (ӀӀӀ) followed by the Freundlich isotherm and the maximum adsorption capacity was 142.8 mg g−1. Also, the results of adsorption kinetic show that the adsorption of Tl (ӀӀӀ) was followed by the pseudo-first-order kinetic model. Moreover, random tree (RT) and artificial neural network (ANN) are employed for prediction of adsorption performance based on effective parameters. The outcomes of soft computing demonstrated that RT (R 2 = 0.95) and ANN (R 2 = 0.87) have acceptable accuracy for estimation and prediction of extraction recovery of Tl (ӀӀӀ).

Polyether Sulfone-Graphene Oxide- Polyvinyl Pyrrolidone Nanocomposite Adsorptive Membrane for Arsenic Removal from Wastewater

Arsenic contamination poses a major public health concern and harms the environment with its toxicity. Long term exposure to a high concentration of arsenic is harmful to human health as well as the environmental biodiversity. This study is aimed to fabricate and investigate the possibility of polyethersulfone-graphene oxide-polyvinyl pyrrolidone (PES-GO-PVP) nanocomposite adsorptive membrane and use it to enhance the removal of arsenic from wastewater. The nanocomposite membrane in this study was fabricated via the non-solvent induced phase separation (NIPS) method with the addition of polyvinylpyrrolidone (PVP) as a pore-forming agent. Based on the characterization results of GO through Fourier-Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD) and Raman spectroscopy, the existence of high quantity of oxygen based functional groups with high degree of oxidation was observed, which indicated that the GO were well-synthesized. The characterization of the membrane indicated that the addition of GO and PVP could impact the membrane hydrophilicity and mechanical stability. Three adsorption parameters (initial concentration of arsenic, pH and contact time) were then optimized using a face-centred central composite design (FCCCD). The arsenic removal efficiency of 88.6 % was obtained with 55 mg/L of initial arsenic concentration, at pH 8 and 75 minutes of contact time between PES-GO-PVP membrane and the arsenic ion. The Langmuir isotherm model fitted the equilibrium data, describing the monolayer adsorption mechanism occurred on the surface of the membrane. Therefore, the results obtained in this study prove the suitability and promising potential of the nanocomposite membrane for effective removal of arsenic through adsorption.

Selective enhancement of non-enzymatic glucose sensor by used PVP modified on α-MoO3 nanomaterials

Among numerous metal oxide based nanocomposites, the polymer incorporated nanocomposites has received fascinated attention as promising electrode materials for inexpensive nonenzymatic glucose sensor. In this study, development of a sensitive and selective glucose sensor was fabricated using molybdenum trioxide (MoO3) via sol–gel method. The synthesized molybdenum trioxide was modified with capping molecule (wt% = 2, 4 and 6) PVP(poly-(vinylpyrrolidone)). The morphology and microstructure of the samples were examined by UV–vis diffuse reflectance spectroscopy (UV–vis-DRS), Fourier Transmission Infra-Red spectroscopy (FT-IR), Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS) and brunauer-emmett-teller (BET) analysis. The fabricated PVP modified MoO3 nanocomposites were utilized as a non-enzymatic glucose sensor in 0.1 M NaOH medium at a pH of 12 at room temperature. The synthesized nanocomposites have magnificent performance towards the detection of glucose. This is owing to enhancement effect as well as mesoporous nature of MoO3/(6%)PVP nanocomposite. The sensor demonstrates a low detection limit of 0.022 µM with a sensitivity of 86.42 µA mM−1 cm−2. It also exhibits good selectivity, stability and simplicity for the rapid detection of glucose. This sensor was opted for the determination of glucose in real sample as well.

Preparation and characterization of polyvinylpyrrolidone/cobalt ferrite functionalized chitosan graphene oxide (CoFe2O4@CS@GO-PVP) nanocomposite

Abstract Cobalt ferrite functionalized chitosan graphene oxide (CoFe2O4@CS@GO) was inserted successfully in polyvinylpyrrolidone (PVP), and its distribution was distinguished through scanning electron microscope (SEM) analysis. Furthermore, the thermal and structural characterizations of the CoFe2O4@CS@GO-PVP nanocomposite were accomplished via the TGA, DSC, FT-IR, and XRD methods. The magnetic characterization of the synthesized nanocomposite was specified by vibrating sample magnetometer (VSM). Results demonstrated the improved thermal stability of pure PVP with the addition of CoFe2O4@CS@GO. The DSC analysis results also showed that the glass transition temperature of 158.9°C–164.8°C was obtained for the CoFe2O4@CS@GO-PVP nanocomposites. The FT-IR spectra indicated that an interaction occurred between CoFe2O4@CS@GO and PVP. Due to a good distribution of CoFe2O4@CS@GO in the PVP matrix, the strong interaction shown by the ~18 cm−1 red shift with good complexation of the carbonyl functional group of PVP with CoFe2O4@CS@GO was observed for the CoFe2O4@CS@GO-PVP (5% w/w) nanocomposite.

Graphdiyne‐Polymer Nanocomposite as a Broadband and Robust Saturable Absorber for Ultrafast Photonics

AbstractAs a rising star of all‐carbon nanomaterial, graphdiyne (GDY) has a direct natural bandgap and features strong light–matter interaction, large optical absorption, superior chemical and optical stability, indicating its broad prospects in the field of photonics and optoelectronics. Herein, the broadband nonlinear absorption and transient absorption characteristics of GDY from visible to infrared region has been studied for the first time, and its promising application in ultrafast photonics has been explored. The large nonlinear absorption coefficient (> −1 cm GW−1), low saturation intensity (<13 GW cm−2), and ultrafast relaxation time (<30 ps) of GDY are demonstrated, which indicates the outstanding potential of GDY in photonics among the emerging novel nonlinear optical (NLO) materials. The GDY is mixed with polyvinylpyrrolidone (PVP) to prepare the GDY–PVP nanocomposite, which further improved the stability of GDY. By using the GDY–PVP nanocomposite as saturable absorption material, ultrashort pulse lasers with pulse duration of 385.5 ps and 688 fs are obtained at 1 and 1.5 µm, respectively. This work reveals the excellent nonlinear optical properties of GDY and lays a foundation for its development in advanced nanophotonic devices.

Influence of γ-ray irradiation doses on physicochemical properties of silver polystyrene polyvinyl pyrrolidone nanocomposites

Abstract Silver – polystyrene polyvinylpyrrolidone nanocomposites were synthesized by polymerization which was induced by γ-ray irradiation. Silver (Ag) nanoparticles were embedded in the polystyrene via subsequent reduction of Ag+ by γ-ray irradiation. Dispersion of Ag nanoparticles was achieved using polyvinylpyrrolidone as a dispersing agent. The morphology and particle size of the new silver/polystyrene/polyvinylpyrrolidone nanocomposite was studied by ultraviolet-visible spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, x-ray diffraction analysis and thermal gravimetric analysis. The prepared nanocomposites showed improved thermal stability. The TEM images demonstrate that well-dispersed Ag nanoparticles were embedded in polystyrene polyvinylpyrrolidone. According to TEM analysis, the size of the nanoparticles was found to be in the range of 15–45 nm. TEM images showed the favored shape of the nanoparticles as spherical. TGA indicated that the thermal stability of polystyrene is enhanced when loaded with Ag nanoparticles and this is clear from the data obtained and the values of the activation energy. This method constitutes a promising way to prepare versatile inorganic-organic polymer nanocomposites. The applied method is both simple and inexpensive and does not use toxic chemicals, unlike other chemical methods.

Alteration of structural, optical and electrical properties of CdSe incorporated polyvinyl pyrrolidone nanocomposite for memory devices

The important enhancement in the structural, dielectric and optical properties of pure polymer and CdSe incorporated polyvinyl pyrrolidone has been reported in this paper. The surface morphology of CdSe/PVP nanocomposite film is studied by using scanning electron microscopy (SEM). The chemical composition of different elements has been reported using energy dispersive X-ray (EDX) spectrum. The structure of polymer nanocomposite is determined with the help of X-ray diffraction (XRD) spectrum and is observed to be hexagonal. Particle size, intercrystalline separation, interplanner spacing, lattice parameters, strain and dislocation factors are calculated using XRD results. Fourier transform infrared spectroscopy (FTIR) and Photoluminescence (PL) analysis have been studied in order to check the possible interaction between CdSe quantum dots and polyvinyl pyrrolidone (PVP) matrix. The ac conductivity of CdSe/PVP nanocomposite is found to be higher as compared to pure polymers. The highest value of conductivity observed at 60203 Hz and at 523 K is found to be [Formula: see text][Formula: see text]Sm[Formula: see text]. Comparative study of dielectric constant, dielectric losses, dissipation factor, electric modulus and impedance has been performed. The semi-circles in impedance measurement for both materials show the bulk electrical properties that result in single relaxation process in CdSe/PVP nanocomposite.

Effect of a PEDOT:PSS modified layer on the electrical characteristics of flexible memristive devices based on graphene oxide:polyvinylpyrrolidone nanocomposites

The electrical characteristics of flexible memristive devices utilizing a graphene oxide (GO):polyvinylpyrrolidone (PVP) nanocomposite charge-trapping layer with a poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)-modified layer fabricated on an indium-tin-oxide (ITO)-coated polyethylene glycol naphthalate (PEN) substrate were investigated. Current-voltage (I-V) curves for the Al/GO:PVP/PEDOT:PSS/ITO/PEN devices showed remarkable hysteresis behaviors before and after bending. The maximum memory margins of the devices before and after 100 bending cycles were approximately 7.69 × 103 and 5.16 × 102, respectively. The devices showed nonvolatile memory effect with a retention time of more than 1 × 104 s. The “Reset” voltages were distributed between 2.3 and 3.5 V, and the “Set” voltages were dispersed between −0.7 and −0.2 V, indicative of excellent, uniform electrical performance. The endurance number of ON/OFF-switching and bending cycles for the devices was 1 × 102, respectively. The bipolar resistive switching behavior was explained on the basis of I-V results. In particular, the bipolar resistive switching behaviors of the LRS and the HRS for the devices are dominated by the Ohmic and space charge current mechanisms, respectively.

Positron annihilation lifetime study of atomic imperfections in nanostructurized solids: On the parameterized trapping in wet‐milled arsenic sulfides As4S4

The phenomenon of positron–electron annihilation in lifetime measuring mode is considered as a tool to study nanostructurization in solids possessing mixed positron and positronium (Ps) trapping. Structural inhomogeneities due to guest nanoparticles in such solids are described in terms of substitution trapping in positron‐ and Ps‐related sites within the same host matrix. The developed approach allows estimation of interfacial free‐volume voids as being responsible for positron trapping and defect‐free bulk positron lifetimes of nanoparticle‐modified solids. For the example of arsenic sulfide, As4S4 nanoparticles embedded in polyvinylpyrrolidone (PVP) environment under high‐energy ball milling, an alternative algorithm to parameterize these structural imperfections is justified. Interfacial free‐volume voids between neighboring nanoparticles filled with loosely packed As4S4 crystallites are considered as the most probable positron trapping sites. The observed variations in mixed positron–Ps trapping modes under nanostructurization are adequately defined with respect to the chemistry of guest nanoparticles. Direct evidence for this algorithm is provided as the basis of experimental three‐term decomposed positron lifetime spectra for As4S4–PVP nanocomposites parameterized with respect to different fitting protocols.

Fabrication and characterization of novel polyvinylpyrrolidone nanocomposites having SiO2 nanoparticles modified with citric acid and L(+)-ascorbic acid

Polyvinylpyrrolidone (PVP) is a synthetic polymer with high physiological compatibility, so incorporation a non-toxic nano-fller within the PVP as the polymer matrix to prepare novel nanocomposites (NC)s leads to bio-safe products for different applications. Therefore, silica nanoparticle (SNP) was chosen as an appropriate nano-filer to insert in the PVP matrix. Surface modification of SNPs was performed to prevent them from agglomeration and make them more compatible with the PVP matrix. Citric acid and vitamin C are two biological molecules which were used as modifiers. After surface treating of SNPs, different weight percentages (3, 5 and 7) of modified SNPs (M-silica) were added to the PVP and PVP/SiO2 NCs were prepared. The prepared NCs were examined using several techniques. The FESEM and TEM observations showed good compatibility of M-silica with the PVP matrix. From histogram diagrams the average particle size of M-silica in PVP matrix was estimated 30–40 nm.

Impact of in situ preparation of CdS filled PVP nano-composite

Cadmium sulfide nanoparticles filled polyvinyl pyrrolidone (PVP) were prepared by in situ wet chemical precipitation technique. X-ray diffraction (XRD), Fourier transforms infrared spectra (FTIR), transmission electron microscopy (TEM) and ultraviolet–visible (UV/Vis) were used to characterize the prepared nano-composites. Density Function Theory (DFT) was used to approve the complexation process. XRD results indicate appearance of two peaks at about 28.1°, 27.4° corresponds to (101) and (002) planes which suggest hexagonal phase of CdS with lattice constants of 4.14, 6.72Å in the polymeric matrix. UV/Vis spectra reveal that nano-composite films show quantum confinement effect. The absorption showed a shift toward the shorter wavelength (blue shift) with decrease in the concentration of Cd+ ions. Optical band gap and particle size were calculated and is in agreement with the results obtained from TEM data. Transmission electron microscopy shows that the prepared CdS nanoparticles were dispersed and nearly uniform in diameter within the polymeric matrix.

Fabrication and Characterization of Iron Oxide Filled Polyvinyl Pyrrolidone Nanocomposites

The present work describes the synthesis and properties of nanomagnetic polymer composites (MPCs) com- prising iron oxide nanoparticles as a filler and polyvinyl pyrrolidone (PVP) as polymer shell. The iron oxide nanoparticles were synthesized under alkaline medium using iron (II) salt. The nanocomposites were synthesized through free radical polymerization under microwave (MW) irradiation. X-ray diffraction reveals the uniform dispersion of iron oxide nanopar- ticles into polymer matrix. Furthermore, scanning electron microscopy images ensure the development of polymer shell around the nanomagnetic core. The magnetic behaviour of MPCs was studied through vibration sample magnetometry. The thermal durability of MPCs was assessed through simultaneous thermogravimetric-differential thermal analysis-differential thermogravimetry. With MW power ranging 25 to 100 W, the polymerization reactions were progressed resulting in MPCs with improved yield over neat PVP.

Preparation of MoS2‐Polyvinylpyrrolidone Nanocomposites for Flexible Nonvolatile Rewritable Memory Devices with Reduced Graphene Oxide Electrodes

A facile method for exfoliation and dispersion of molybdenum disulfide (MoS2) with the aid of polyvinylpyrrolidone (PVP) is proposed. The resultant PVP-coated MoS2 nanosheets, i.e., MoS2-PVP nanocomposites, are well dispersed in the low-boiling ethanol solvent, facilitating their thin film preparation and the device fabrication by solution processing technique. As a proof of concept, a flexible memory diode with the configuration of reduced graphene oxide (rGO)/MoS2-PVP/Al exhibited a typical bistable electrical switching and nonvolatile rewritable memory effect with the function of flash. These experimental results prove that the electrical transition is due to the charge trapping and detrapping behavior of MoS2 in the PVP dielectric material. This study paves a way of employing two-dimensional nanomaterials as both functional materials and conducting electrodes for the future flexible data storage.

Up-Conversion Luminescence of NaYF4:Yb3+/Er3+ Nanoparticles Embedded into PVP Nanotubes with Controllable Diameters

NaYF4:Yb3+/Er3+/polyvinylpyrrolidone (PVP) up-conversion (UC) luminescent nanotubes were synthesized by the electrospinning technique. The diameters of the nanotubes were controllable by changing the electrospinning voltages. The structure and the optical properties were studied by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), photoluminescence (PL) spectra, and fluorescence microscope. The NaYF4:Yb3+/Er3+/PVP nanocomposites simultaneously possessed UC luminescent property, active surfaces and tubular structure. PVP molecules were found to have an important influence on the UC luminescence of NaYF4:Yb3+/Er3+/PVP nanotubes. Compared with those in pure NaYF4:Yb3+/Er3+ nanoparticles, the relative intensities of violet, blue, and green to red emissions were increased in NaYF4:Yb3+/Er3+/PVP nanotubes. It is owing to the existence of PVP molecules, which might produce the passivation on NaYF4:Yb3+/Er3+ nanopa...

Improved Antifouling Property of PES Ultrafiltration Membranes Using Additive of Silica−PVP Nanocomposite

To improve the surface coverage of polyvinylpyrrolidone (PVP) on membrane surfaces and further enhance the antifouling property, a silica−PVP nanocomposite was synthesized and used as a novel hydrophilic additive to modify polyethersulfone (PES) membranes. Transmission electron microscopy (TEM) observation showed that PES membranes, using additives of PVP and silica−PVP nanocomposites, have similar asymmetric structures. X-ray photoelectron spectroscopy (XPS) measurement indicated that the near-surface coverage of PVP for PES membrane with a silica−PVP nanocomposite additive is greater than that with a PVP additive. Protein ultrafiltration experiment also showed that the antifouling ability of PES membrane with a silica-PVP nanocomposite additive is stronger than that with a PVP additive. The hydrophilic modification with a silica−PVP nanocomposite is an appropriate method for improved antifouling property of PES ultrafiltration membranes.

Conductivity and adhesion enhancement in low-temperature processed indium tin oxide/polymer nanocomposites

We report on the conductivity and adhesion enhancement of indium tin oxide (In 2O 3:Sn; ITO) nanoparticle films by the application of polymers as matrix material. We fabricated ITO layers at a maximum process temperature of 130 °C by modifying and spin-coating nanoparticulate ITO dispersions. Dispersions containing the organic film-forming agent polyvinylpyrrolidone (PVP) and the organofunctional coupling agent 3-methacryloxypropyltrimethoxysilane (MPTS) have been developed to obtain transparent and conducting coatings on substrates which do not withstand high process temperatures like polymers or already processed glasses. The layers were cured by UV-irradiation as well as by low-temperature heat treatment ( T = 130 °C) in air and under forming gas atmosphere (N 2/H 2). The influence of the additives on the electrical, optical, morphological and mechanical layer properties is reported. Compared to best pure ITO layers (3.1 Ω − 1 cm − 1 ), the ITO–MPTS–PVP nanocomposite coatings exhibit a conductance of 9.8 Ω − 1 cm − 1 . Stable sheet resistances of 750 Ω/□ at a coexistent transmittance of 86% at 550 nm for a layer thickness of about 1.3 µm were achieved. The conductance enhancement is a consequence of the consolidation of the ITO nanoparticle network due to the acting shrinkage forces caused either by drying in the case of PVP or UV-irradiation induced condensation and polymerization reactions in the case of MPTS.

Optical nonlinearity of ZnS–polyvinyl pyrrolidone nanocomposite suspension

ZnS–polyvinyl pyrrolidone nanocomposite was prepared by a simple wet-chemical route. TEM and x-ray diffraction confirmed the formation of nanometre size ZnS particles within the polymer matrix. The average particle size was between 10 and 12 nm. The third-order susceptibility χ(3) of the nanocomposite suspension was measured by employing a single beam z-scan setup with 38 ps laser pulses at 532 nm. The results show that the ZnS nanoparticle exhibits saturable absorption and large third-order susceptibility χ(3) (10−9 esu). The difference in optical nonlinearity between the ZnS/PVP suspension and another ZnS nanocomposite was discussed.