PVP Matrix Research Articles

Enhanced Dielectric Properties of the ZnO and TiO2 Nanoparticles Dispersed Poly(Vinyl Pyrrolidone) Matrix-Based Nanocomposites

Polymer nanocomposites (PNCs) are state-of-the-art composites consisting of nanofiller-materials included in polymer matrices and bearing the integrated, promising properties of both the polymer and the nanofiller. They are now renowned as advanced materials for the development of polymer nanotechnology-based flexible and stretchable-type multifunctional organoelectronic devices as well as improved daily use products. Characterization of their dielectric properties permits some of these PNCs to be used as polymer nanodielectrics (PNDs), resulting in confirming the suitability and performance improvement of the electronic devices. This work deals with the dielectric behavior of wide band gap semiconducting zinc oxide (ZnO) and titanium dioxide (TiO2) nanoparticles dispersed biodegradable poly(vinyl pyrrolidone) (PVP) matrix-based PNC films. The results confirmed the tunable and considerably increased dielectric permittivity with increasing nanofillers content in the range 1–5 wt% for these PNC films. The influence of the ZnO and TiO2 nanoparticles sizes and their dielectric permittivities, and also of the polymer–nanoparticle interactions and interfaces, on the dielectric polarization and charge conduction mechanisms of the PNC films with increasing frequency from 2 × 101 to 106 Hz were identified, and the suitability of these materials as biodegradable PNDs is discussed. Further, the appreciable homogeneous distribution of these crystalline nanoinclusions in the amorphous PVP matrix and the successful formation of hybrid nanocomposites were ascertained from our XRD results.

Effect of graphene nanoplatelets concentration on optical, dielectric and electrical properties of poly(2-ethyl-2-oxazoline)–polyvinylpyrrolidone–graphene nanocomposites

The polymer nanocomposites with good optical, dielectric and electrical properties have taken faithfulness in research due to their distinguishing benefits in electronic applications. Hence, in the present investigation, poly(2-ethyl-2-oxazoline)–polyvinylpyrrolidone–graphene nanoplatelets (PEOX–PVP–GNPs) nanocomposites were synthesized and their properties were evaluated. Field emission scanning electron microscopy micrograph images showed a uniform dispersion of GNPs within the PEOX–PVP binary matrix. X-ray diffraction analysis illustrated the increase of crystallinity of nanocomposites with increasing weight percentage of GNPs. Fourier-transform infrared spectroscopy confirmed intermolecular interaction between the PEOX–PVP matrix and the GNPs. PEOX–PVP–graphene nanocomposite shows decrease in the optical energy band gap and increase in Urbach energy with increasing GNPs concentration. PEOX–PVP–10 wt% graphene nanocomposite has the lowest band gap (= 1.2 eV) and highest Urbach energy (= 7.43 eV). Dielectric constant, dielectric loss and tangent loss of nanocomposites decrease with increasing frequency of the applied electric field. On the other hand, the AC electrical conductivity of nanocomposites is independent of frequency, at lower frequencies, and increases with increasing frequency, at higher frequencies. PEOX–PVP–10 wt% graphene nanocomposite has the higher dielectric constant (= 16), low dielectric loss (= 0.09) and low AC conductivity (= 8.47 × 10−9 S/cm) at 1 kHz. This nanocomposite having good dielectric, electrical and optical properties may find use in electronic and optoelectronic applications due to its enhanced properties.

Effectively nanofiller concentration tunable dielectric properties of PVP/SnO2 nanodielectrics

Polymer nanodielectrics (PNDs) are tremendously important materials used in fabrication of flexible-type advanced electronic devices owing to their promising dielectric properties. In this study, dielectric and electrical behaviour of poly(vinyl pyrrolidone)/tin oxide (PVP/SnO2) nanocomposite films with 0–5 wt% SnO2 concentrations are reported. The results in the frequency range 20 Hz–1 MHz demonstrate that the dielectric permittivity, ac electrical conductivity, and also interfacial polarization relaxation of these materials can be effectively tuned with SnO2 concentration in the PVP matrix which confirms them as appealing biodegradable PNDs. X-ray diffraction study evidences presence of SnO2 nanoparticles and their good dispersibility in these solution cast prepared films.

Optical properties of PbO/ZnO core/shell dispersed in PVP matrix

The core/shell material shows novel properties depending upon their relative valance and conduction band shift. In the present work, PbO and PbO/ZnO core/shell nanoparticles are prepared through chemical technique using PVP as capping agent. The core/shell PbO/ZnO exhibits the X-Ray diffraction peaks of both the material, thereby confirming the formation of core/shell structure. The particle size and strain of all the material are calculated employing W.H technique. The UV visible absorption spectra of PbO show a blue shift of its absorption edge. However, after coating with ZnO shell the absorption edge become red shifted. The band gaps were estimated from Taue plots which were found to be reduced from 3.2 eV to 2.74 eV. The reduction of band gap is attributed to the incorporation of defects in terms of shell. The photoluminescence spectra show a band to band emission around 345 nm along with emission from other impurities. After coating the near band gap emission is red shifted towards 374 nm. The PL intensity of the core reduced after shelling. This effect may be attributed to the change of recombination kinetics governed by induced defects.

Solid lipid nanoparticles self-assembled from spray dried microparticles.

We report the self-assembly of drug-loaded solid lipid nanoparticles (SLNs) from spray dried microparticles comprising poly(vinylpyrrolidone) (PVP) loaded with glyceryl tristearate (GTS) and either indomethacin (IMC) or 5-fluorouracil (5-FU). When the spray dried microparticles are added to water, the PVP matrix dissolves and the GTS and drug self-assemble into SLNs. The SLNs provide a non-toxic delivery platform for both hydrophobic (IMC) and hydrophilic (5-FU) drugs. They show extended release profiles over more than 24 h, and in permeation studies the drug cargo is seen to accumulate inside cancer cells. This overcomes major issues with achieving local intestinal delivery of these active ingredients, in that IMC permeates well and thus will enter the systemic circulation and potentially lead to side effects, while 5-FU remains in the lumen of the small intestine and will be secreted without having any therapeutic benefit. The SLN formulations are as effective as the pure drugs in terms of their ability to induce cell death. Our approach represents a new and simple route to the fabrication of SLNs: by assembling these from spray-dried microparticles on demand, we can circumvent the low storage stability which plagues SLN formulations.

Effect of Zinc Content on Structural, Functional, Morphological, Resonance, Thermal and Magnetic Properties of Co1−xZnxFe2O4/PVP Nanocomposites

Integrate Zinc substituted cobalt ferrites have incorporated by the Co-precipitation technique. The XRD pattern shows the formation and microstructure evolutions of nanocomposites. Cationic coordination, exchange interactions raised between the tetrahedral site in high frequency and octahedral site in the lower frequency described FTIR results. The SEM images showed that the spongy morphology with PVP matrix and fewer agglomerated grains. It exposes the grains and the range of grains recovered from 1μ to 400 nm, which is in compromise with the test of grain size of XRD. VSM study reveals that the magnetization of substances raises by incrementing the non-magnetic (Zn) material incorporated cobalt ferrite. EPR confirmed that synthesized materials exhibited ferromagnetic properties from Lande g-factor. TGA/DSC curve reports the weight loss and heat flow by endothermic absorption through exothermic emission in the ferrite. It used these materials for the potential effort like magneto-optical recording media and magnetic sensors.

The Effect of γ-Radiation on Antimicrobial Properties of Polyvinylpyrrolidone-Based Gels

The effect of γ-radiation on antimicrobial properties of gels based on polyvinylpyrrolidone was investigated. It was shown that the effects of [gamma]-radiation do not alter the antimicrobial activity of the antibiotics fosfomycin and gentamicin in the PVP matrix and that dioxidine loses its antimicrobial activity with increasing radiation dose. At low concentrations of the antibiotics, no synergistic effect from the simultaneous use of fosfomycin and gentamicin was observed; it started to develop only at a fosfomycin concentration of 5%.

Broadband dielectric spectroscopy as an experimental alternative to calorimetric determination of the solubility of drugs into polymer matrix: Case of flutamide and various polymeric matrixes

In this paper we determined the solubility limits of the amorphous flutamide within the two different polymeric matrixes – poly vinylpyrrolidone and poly vinylacetate. In order to achieve this goal, series of broadband dielectric spectroscopy measurements were performed. As a result we found that the maximal amount of the drug that can be successfully dissolved within the PVAc (maintaining the non-supersaturated conditions) is equal to 35 wt% of the amorphous solid dispersion system. Interestingly enough similar results, in terms of solubility limits, were achieved utilizing significantly higher amount of the pharmaceutical – 71 wt% – in the PVP matrix. Accordingly, we established the following relationship in the solubility limits of the amorphous flutamide dispersed within examined polymer matrixes: PVP > PVAc. It is worth highlighting that in order to preserve the thermodynamic stability – one of the two contributors to the physical stability – drug loading in the amorphous solid dispersion system should not exceed its solubility limits. Hence, choosing appropriate amount of the polymer addition will determine if obtained system remains physically stable. Subsequently, we presented the “stability maps” for all investigated FL-based ASD systems from which one might predict the stabilization effect exerted by certain amount of polymer.

Preparation and Characterization of Polyvinylpyrrolidone/Cellulose Nanocrystals Composites.

Composite films and aerogels of polyvinylpyrrolidone/cellulose nanocrystals (PVP/CNC) were prepared by solution casting and freeze-drying, respectively. Investigations into the PVP/CNC composite films and aerogels over a wide composition range were conducted. Thermal stability, morphology, and the resulting reinforcing effect on the PVP matrix were explored. FTIR, TGA, DSC, X-ray diffraction, SEM, and tensile testing were used to examine the properties of the composites. It was revealed PVP-assisted CNC self-assembly that produces uniform CNC aggregates with a high aspect ratio (length/width). A possible model of the PVP-assisted CNC self-assembly has been considered. Dispersibility of the composite aerogels in water and some organic solvents was studied. It was shown that dispersing the composite aerogels in water resulted in stable colloidal suspensions. CNC particles size in the redispersed aqueous suspensions was near similar to the CNC particles size in never-dried CNC aqueous suspensions.

Effect of fullerene content on the thermal, microstructure, and electrokinetic properties of fullerene/poly(vinyl pyrrolidone) nanofluids and nanocomposites

In this study I report the thermal stability, microstructures, dynamic light scattering (DLS) and electro-kinetic effect in the fullerene (C60):poly(vinyl pyrrolidone) PVP nanofluids (NFs) and nanocomposite films. An improvement in the degradation temperature of C60:PVP nanocomposite reported here is ascribed to free radical scavenging ability of C60. An analysis of DLS data in terms of polydispersity index (PDI) reveals a well dispersed structure of C60 assemblies with PVP in liquid medium. The typical electro-kinetic parameters such as zetapotential (ξ) and surface conductivity (σsc) in a NF evaluates the magnitude of electrostatic repulsion between C60 particles and such measurement tender a way to boost stability of C60 nanoparticles in presence of PVP molecules in a particular carrier. Microstructures in various films were found to vary with increasing in the C60 content and decreasing in the relative PVP content in the nanocomposites. Highest thermal degradation temperature (∼ 422 °C) was observed for the sample consisting of 13.9 μM C60 owing to uniform distribution of C60 in the PVP matrix with a low PDI (0.272).

Carbon dots with efficient solid-state red-light emission through the step-by-step surface modification towards light-emitting diodes.

Carbon dots (CDs) have attracted extensive attention over the past decade due to their excellent advantages. However, few attempts have been reported for realizing the long-wavelength emission, especially for obtaining efficient solid-state red emission with high photoluminescence quantum yield (QY). Herein, we developed highly red light emitting CDs by the step-by-step surface modifications of the nitrogen-doped CDs. By introducing hexadecyltrimethyl ammonium bromide to modulate a red CD aqueous solution, the photoluminescence QY increases from 23.2% to 43.6%. Furthermore, we dispersed CDs in a PVP matrix for a solid-state film, where the solid-state quenching was effectively suppressed, and high QY (41.3%) of red light emission was achieved. Taking advantage of the as-prepared red light emitting CDs combining with the reported high quantum yield blue and green light emitting CDs, we realized UV-pumped WLEDs with tunable correlated color temperature from 7879 to 2961 K. Moreover, a high color rendering index (CRI) of 93 for WLEDs was realized, which is superior than the best records for the semiconductor quantum dot based WLEDs. Finally, the red light emitting CDs were demonstrated to have promising application as a red color converter in traditional YAG-based WLEDs to improve their CCT and CRI.

Employment of ultrasonic irradiation for production of poly(vinyl pyrrolidone)/modified alpha manganese dioxide nanocomposites: Morphology, thermal and optical characterization

This work explains the production, morphology, and features of novel nanocomposite (NC) established on poly(vinyl pyrrolidone) (PVP) as polymer background and modified alpha manganese dioxide (α-MnO2) nanorod (NR) asan efficient filler. At first, one-dimensional α-MnO2 nanorods (NRs) were produced by a hydrothermal technique and then they were amended with stearic acid (SA) by a solvothermal process. In following, the NCs were made by adding different volumes of α-MnO2-SA NR (1, 3 and 5wt%) in the PVP matrix through ultrasonic irradiation as a green, low-cost, fast, and useful technique. Structural and morphological descriptions confirm crystallinity of α-MnO2-SA NRs and showed that NRs have been separately dispersed in PVP matrix with rod-like morphology and diameter of about 40–60nm. The use of modifier and ultrasonic waves is accountable for good homogeneities of NRs. Thermogravimetric analysis revealed that thermal permanency of the obtained NCs has grown with increasing the α-MnO2-SA content. Also, the UV–vis absorption of NCs was enhanced with the incorporation of the modified α-MnO2 NR in PVP matrix. The substantial perfections in NCs properties are associated to compatible intermolecular relations between the surface modifying groups of the α-MnO2-SA and PVP chain.

Chitosan/zinc oxide-polyvinylpyrrolidone (CS/ZnO-PVP) nanocomposite for better thermal and antibacterial activity

A new biopolymer based ZnO-PVP nanocomposite was successfully synthesized by single step in situ precipitation method using chitosan as biosurfactant, zinc chloride as a source material, PVP as stabilizing agent and sodium hydroxide as precipitating agent. The chemical bonding and crystalline behaviors of chitosan, zinc oxide and PVP were confirmed by FT-IR and XRD analysis. The biopolymer connected ZnO particles intercalated PVP matrix was layer and rod like structure appeared in nanometer range confirmed by HR-SEM and TEM analysis. The surface topography image of CS/ZnO-PVP nanocomposite was obtained in the average thickness of 12nm was confirmed by AFM analysis. Thermal stability of cationic biopolymer based ZnO intercalated PVP has higher stability than CS-PVP and chitosan. Consequently, antimicrobial activity of chitosan/ZnO-PVP matrix acts as a better microbial inhibition activity than PVP-ZnO nanocomposite. The obtained above results demonstrate that CS and ZnO intercalated PVP matrix has better reinforced effect than other components. Therefore, Chitosan/ZnO-PVP nanocomposite may be a promising material for the biomedical applications.

FIBROUS SILICA-HYDROXYAPATITE COMPOSITE BY ELECTROSPINNING

New nanocomposite membrane was fabricated by electrospinning. The nanocomposite combines a glass and hydroxyapatite (HA). This research proposed the incorporation of glass to counteract the brittleness of HA in a composite formed by coaxial fibers which will be used for bone replacement. Calcium phosphate ceramics are used widely for dental and orthopedic reasons, because they can join tightly through chemical bonds and promote bone regeneration. Precursors HA and SiO2 were synthetized through the sol-gel method and then incorporated into a polymeric PVP matrix; later they were processed by coaxial electrospinning to obtain fibers with an average diameter of 538 nm which were characterized with techniques such as Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy, Differential Thermal Analysis and Scanning Electron Microscopy. Chemical and physical characterization of the membranes evidenced fibers in a coaxial disposition with a glass core and hydroxyapatite cover. The micro-porous fibers have many potential uses in the repair and treatment of bone defects, drug delivery and tissue engineering. Through ATR-FTIR and SEM-EDX analysis the presence of characteristic chemical groups, the fiber composition and microstructure were determined.

Utilization of ultrasonic irradiation as a green and effective strategy to prepare poly(N-vinyl-2-pyrrolidone)/modified nano-copper (II) oxide nanocomposites

The present paper describes the result of investigations into preparation of novel nanocomposites (NCs) based on poly(N-vinyl-2-pyrrolidone) (PVP) as a biocompatible polymer and modified copper (II) oxide nanoparticles (NPs) as a nano-filler. To achieve optimum NCs properties, different ratios of modified copper (II) oxide NPs (3, 5, and 7wt%) were used to fabricate PVP NCs and also the ultrasonic irradiation was utilized to perform these processes as a fast and effective method. Subsequently, the structure of the obtained nanohybrids was characterized by various techniques. The suitable incorporation between PVP matrix and modified CuO NPs can be seen from the FT-IR spectra. The obtained NCs indicated an efficient thermal improvement in comparison to the pristine polymer. Also, the uniform dispersion of modified CuO NPs in the PVP matrix was detected by FE-SEM and EDX. According to UV absorption spectra, it is clear that these NCs can be used in UV protecting applications.

Surface enhanced Raman spectroscopy in nanofibers mats of SiO2-TiO2-Ag

Surface-enhanced Raman scattering (SERS) is a powerful tool with high potential for detection of dilute analytes. Nanofibers functionalized by metal nanostructures and particles are exploited as effective flexible substrates for SERS analysis. SERS-active substrates of silice-titania-silver (SiO2-TiO2-Ag) nanofibers were prepared using a simple approach involving electrospinning. We report a simple method for quantitative SERS analysis using SiO2-TiO2-Ag nanofibers as the SERS substrate. Precursors SiO2 and TiO2 were synthetized through the sol-gel method and then incorporated into a polymeric PVP matrix; later they were processed by coaxial electrospinning to obtain fibers with an average diameter of 250nm. The SiO2-TiO2-Ag structure was demonstrated by Raman, XRD, IR, SEM and EDX. Through infrared spectroscopy it was possible to evaluate the thermal evolution of the sol-gel process. The Titania phase transformation was observed around 800°C and the hydroxyl group loss was detected between 500 and 800°C. The presence of two Titania phases, anatase and rutile were analized with DRX. Using Pyridine (1nM) as probe molecule the SERS effect of the scaffold was evaluated and it was determined that the vibration modes 8a, 8b, and 15 were the most amplified signals with a 3 orders of magnitude factor. With this it was concluded that the Silica-Titania-Silver Scaffold is a feasible as a SERS enhancer.

Surface Modification of ZrO2 Nanoparticles with Biosafe Coupling Agents, Preparation of Poly(vinyl pyrrolidone) Nanocomposites: Optical, Thermal, and Morphological Studies

AbstractIn this study, a series of green and environmental friendly nanocomposites (NCs) were prepared using poly(vinyl pyrrolidone) (PVP), citric acid, vitamin C, and ZrO2 nanoparticles (NPs) as biosafe and biocompatible agents. To develop dispersion and interfacial compatibility of ZrO2 NPs with PVP matrix, at first the surface of NPs was modified with citric acid and vitamin C. Then, the novel NCs were fabricated by adding various amounts of modified ZrO2 NPs in the PVP matrix. All of the steps were performed with ultrasonic irradiation as a safe method. The obtained NCs were investigated by different techniques. The Fourier transform infrared spectroscopy results indicated interactions between the NPs and modifier agents. Thermogravimetric analysis results illustrated that the thermal stability of NC 7 wt% in comparison to the pure polymer was enhanced. The surface topography and morphology of the NCs were studied by field emission scanning electron microscopy, and transmission electron microscopy techniques. The results showed that the nanofiller were homogeneously dispersed in the polymer matrix. Finally, the incorporation of the modified ZrO2 NPs influenced the UV–Vis absorption of the pure PVP.

Fabrication of electrospun nanofibres of BCS II drug for enhanced dissolution and permeation across skin

The present work reports preparation of irbesartan (IBS) loaded nanofibre mats using electrospinning technique. The prepared nanofibres were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray diffraction analysis, in vitro diffusion and ex vivo skin permeation studies. FTIR studies revealed chemical compatibility of IBS and polyvinyl pyrrolidine (PVP K-30). SEM images confirmed formation of nanofibres wherein IBS existed in amorphous form as revealed by DSC and XRD analyses. The prepared nanofibre mats of IBS were found to be superior to IBS loaded as cast films when analysed for in vitro IBS release and ex vivo skin permeation studies since the flux of IBS loaded nanofibres was 17 times greater than as cast film. The improvement in drug delivery kinetics of IBS loaded nanofibres could be attributed to amorphization with reduction in particle size of IBS, dispersion of IBS at molecular level in PVP matrix and enormous increase in the surface area for IBS release due to nanonization. Thus transdermal patch of IBS loaded nanofibres can be considered as an alternative dosage form in order to improve its biopharmaceutical properties and enhance therapeutic efficacy in hypertension.

Preparation and Characterization of Novel Hybrid Nanocomposites by Free Radical Copolymerization of Vinyl pyrrolidone with Incompletely Condensed Polyhedral Oligomeric Silsesquioxane

A new series of hybrid nanocomposites based on poly (vinyl pyrrolidone) (PVP) containing incompletely condensed polyhedral oligomeric silsesquioxane (IC-POSS) with different percentages of POSS were prepared via free radical copolymerization. Incompletely condensed, phenyl-POSS (Na3O12Si7(C6H5)7) with the highly reactive group of trisodium silanolate was used to prepare desire IC-POSS by nucleophilic substitution reaction. The products were characterized by Fourier transform infrared, X-ray diffraction, scanning electron microscopy, differential scanning calorimetry and thermogravimetric analysis techniques. The results of analysis confirmed that there are good interactions between IC-POSS and the PVP matrix. The thermal stability of the PVP was enhanced with the addition of small amounts of nano-filler. The solubility of the nanocomposites has been also tested and the results showed that with increasing the IC-POSS content the hydrophobicity of nanocomposites were increased.

The Effects of Poly(amide–imide)/SiO2 Nanocomposite Containing N‐Trimellitylimido‐l‐Methionine Diacid as a Filler on the Thermal and Morphological Properties of Poly(vinyl pyrrolidone) Composites

ABSTRACTIn this article, a simple ultrasonic irradiation method for preparing novel poly(vinyl pyrrolidone)/poly(amide–imide)‐SiO2 nanocomposites (PVP/PAI‐SiO2 NC)s is reported. For this purpose, PAI‐SiO2 NC as a filler was embedded in PVP. The presence of incorporated filler into the PVP matrix is established by Fourier transform infrared spectroscopy, X‐ray diffraction, field emission scanning electron microscopy (FE‐SEM), atomic force microscopy, and transmission electron microscopy (TEM). The filler has an average particle size of 10–20 nm as observed by TEM. The FE‐SEM images show that the filler was uniformly dispersed in the polymer matrix. Thermogravimetric analysis results showed that the addition of filler favored the enhancement of thermal stability of PVP/PAI‐SiO2 NCs.