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1.
The proton conducting solid-state polymer electrolyte comprising blend of poly(vinyl alcohol) (PVA) and poly(N-vinylimidazole) (PVIM), ammonium tetrafluoroborate (NH4BF4) as salt, and polyethylene glycol (PEG) (molecular weight 300 and 600) as plasticizer is prepared at various compositions by solution cast technique. The prepared films are characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray diffraction, and scanning electron microscopy analysis. The conductivity–temperature plots are found to follow an Arrhenius nature. The conductivity of solid polymer electrolytes is found to depend on salt and plasticizer content and also on the dielectric constant value and molecular weight of the plasticizer. Maximum ionic conductivity values of 2.20?×?10?4 and 1.28?×?10?4?S?cm?1 at 30 °C are obtained for the system (PVA–PVIM)?+?20 wt.% NH4BF4?+?150 wt.% PEG300 and (PVA–PVIM)?+?20 wt.% NH4BF4?+?150 wt.% PEG300, respectively. The blended polymer, complexed with salt and plasticizer, is shown to be a predominantly ionic conductor. The proton transport in the system may be expected to follow Grotthuss-type mechanism.  相似文献   

2.
Solid polymer electrolyte films based on poly(vinyl chloride)-lithium triflate (PVC-LiCF3SO3) have been prepared by the solution-cast technique in various concentrations. The film with the highest conductivity was used to prepare plasticised polymer electrolyte films by using poly(ethlene glycol) (PEG) of different molecular weights, i.e., 200, 400 and 600 gmol−1. These films were prepared to study the effects of addition of low molecular weights PEG on the lithium ionic conduction of the PVC based polymer electrolyte. The films were characterised by electrochemical impedance spectroscopy (EIS) and Fourier transform infrared-spectroscopy (FTIR). Results indicate that the molecular weight has an inverse effect on the conductivity and this has been accounted for by FTIR. Paper presented at the International Conference on Functional Materials and Devices 2005, Kuala Lumpur, Malaysia, June 6 – 8, 2005.  相似文献   

3.
A solid polymer electrolyte (SPE) composites consisting blend of poly(ethylene oxide) (PEO) and poly(ethylene glycol) (PEG) as the polymer host with LiCF3SO3 as a Li+ cation salt and TiO2 nanoparticle which acts as a filler were prepared using solution-casting technique. The SPE films were characterized by X-ray diffraction and Fourier transform infrared analysis to ensure complexation of the polymer composites. Frequency-dependent impedance spectroscopy observation was used to determine ionic conductivity and dielectric parameters. Ionic conductivity was found to vary with increasing salt and filler particle concentrations in the polymer blend complexes. The optimum ambient temperature conductivity achieved was 2.66?×?10?4?S?cm?1 for PEO (65 %), PEG (15 %), LiCF3SO3 (15 %), ethylene carbonate (5 %), and TiO2 (3 %) using weight percentage. The dielectric relaxation time obtained from a loss tangent plot is fairly consistent with the conductivity studies. Both Arrhenius and VTF behaviors of all the composites confirm that the conductivity mechanism of the solid polymer electrolyte is thermally activated.  相似文献   

4.
Gallium antimonide (GaSb) films were deposited onto fused silica and n-Si (100) substrates by coevaporating Ga and Sb from appropriate evaporation sources. The films were polycrystalline in nature. The size and the shape of the grains varied with the change in the substrate temperature during deposition. The average surface roughness of the films was estimated to be 10 nm. Grain boundary trap states varied between 2×1012 and 2.2×1012 cm?2 while barrier height at the grain boundaries varied between 0.09 eV and 0.10 eV for films deposited at higher temperatures. Stress in the films decreased for films deposited at higher temperatures. XPS studies indicated two strong peaks located at ~543 eV and ~1121 eV for Sb 3d3/2 and Ga 2p3/2 core-level spectra, respectively. The PL spectra measured at 300 K was dominated by a strong peak located ~0.55 eV followed by two low intensity peaks ~0.63 eV and 0.67 eV. A typical n-Si/GaSb photovoltaic cell fabricated here indicated V oc~311 mV and J~29.45 mA/cm2, the density of donors (N d)~3.87×1015 cm?3, built in potential (V bi)~0.48 V and carrier life time (τ)~28.5 ms. Impedance spectroscopy measurements indicated a dielectric relaxation time ~100 μs.  相似文献   

5.
Polyethylene glycol (PEG) molecules act as a reducing and stabilizing agent in the formation of silver nanoparticles. PEG undergoes thermal oxidative degradation at temperatures over 70 °C in the presence of oxygen. Here, we studied how the temperature and an oxidizing atmosphere could affect the synthesis of silver nanoparticles with PEG. We tested different AgNO3 concentrations for nanoparticles syntheses using PEG of low molecular weight, at 60 and 100 °C. At the higher temperature, the reducing action of PEG increased and the effect of PEG/Ag+ ratio on nanoparticles aggregation changed. These results suggest that different synthesis mechanisms operate at 60 and 100 °C. Thus, at 60 °C the reduction of silver ions can occur through the oxidation of the hydroxyl groups of PEG, as has been previously reported. We propose that the thermal oxidative degradation of PEG at 100 °C increases the number of both, functional groups and molecules that can reduce silver ions and stabilize silver nanoparticles. This degradation process could explain the enhancement of PEG reducing action observed by other authors when they increase the reaction temperature or use a PEG of higher molecular weight  相似文献   

6.
TiO2 photocatalyst film recently has been utilized as the potential candidate for the wastewater treatment, due to its high stability and low toxicity. In order to further increase the photocatalytic ability and stability, different molecular weight of polyethylene glycol (PEG) were used to modify TiO2 structure to synthesize porous thin film used in the developed Photocatalytic-Ultrasonic system in this work. The results showed that PEG2000 modified TiO2 calcinated under 450 °C for 2 h exhibited the highest photocatalytic activity, attributed to the smallest crystallite size and optimal particle size. Over 95.0% of rhodamine B (Rh B) was photocatalytically degraded by optimized PEG2000-TiO2 film after 60 min of UV irradiation, while only about 50.8% of Rh B was decolored over pure TiO2 film. Furthermore, optimized PEG2000-TiO2 film was used in a circular Photocatalytic-Ultrasonic system, and the obtained synergy (0.6519) of sonophotocatalysis indicated its extremely high efficiency for Rh B degradation. In this Photocatalytic-Ultrasonic system, larger amount of PEG2000-TiO2 coated glass beads, stronger ultrasonic power and longer experimental time could result to higher degradation efficiency of Rh B. In addition, repetitive experiments showed that about 97.2% of Rh B were still degraded in the fifth experiment by sonophotocatalysis using PEG2000-TiO2 film. Therefore, PEG2000-TiO2 film used in Photocatalytic-Ultrasonic system has promising potential for wastewater treatment, due to its excellent photocatalytic activity and high stability.  相似文献   

7.
The glass transitions in talc- and titanium-dioxide-filled free films of hydroxypropyl methylcellulose (HPMC) as well as HPMC in combination with either polyethylene glycol (PEG) 400 or polyvinyl alcohol (PVA) have been examined by differential scanning calorimetry. The glass transition temperatures (Tg's) of HPMC and HPMC/PEG 400 films were increased in the presence of either talc or titanium dioxide, with the former the more effective Tg enhancer. In contrast, the Tg 's of HPMC/PVA films were virtually unchanged in the presence of the fillers, and this behavior was attributed to the influence of the vinyl backbone of PVA. The Tg's of filled and unfilled HPMC and HPMC/PVA films were lower after storage for 1 year, but the Tg of HPMC/PEG 400 remained unchanged. Phase separation of the mixed polymer systems also occurred following prolonged storage. These phenomena were related to changes in the moisture content and crystal-linity of the films.  相似文献   

8.
Biodegradable polymer electrolyte films based on poly(ε-caprolactone) (PCL) in conjunction with lithium tetrafluoroborate (LiBF4) salt and 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4) ionic liquid were prepared by solution cast technique. The structural, morphological, thermal, and electrical properties of these films were examined using X-ray diffraction (XRD), optical microscopy (OM), differential scanning calorimetry (DSC), and impedance spectroscopy. The XRD and OM results reveal that the pure PCL possesses a semi-crystalline nature and its degree of crystallinity decreases with the addition of LiBF4 salt and EMIMBF4 ionic liquid. DSC analysis indicates that the melting temperature and enthalpy are apparently lower for the 40 wt% EMIMBF4 gel polymer electrolyte as compared with the others. The ambient temperature electrical conductivity increases with increasing EMIMBF4 concentration and reaches a high value of ~2.83?×?10?4 S cm?1 for the 85 PCL:15 LiBF4 + 40 wt% EMIMBF4 gel polymer electrolyte. The dielectric constant and ionic conductivity follow the same trend with increasing EMIMBF4 concentration. The dominant conducting species in the 40 wt% EMIMBF4 gel polymer electrolyte determined by Wagner’s polarization technique are ions. The ionic conductivity of this polymer electrolyte (~2.83?×?10?4 S cm?1) should be high enough for practical applications.  相似文献   

9.
Perovskite-type nitrogen substituted SrTiO3 thin films were deposited with a one-step process by RF-plasma assisted pulsed laser deposition from a SrTiO3 target using a N2 plasma, while deposition with a NH3 plasma yields films with almost no incorporated nitrogen. The deposited films exhibit a cubic perovskite-type crystal structure and reveal oriented growth on MgO(100) substrates. The unit cell parameters of the studied N-doped SrTiO3 films range within 3.905<a<3.918 Å, which is slightly larger than for SrTiO3 (a=3.905 Å). The nitrogen content in the deposited films varies from 0.2 to 0.7 atom%. The amount of incorporated nitrogen in the films decreases with increasing RF-power, while the N2 flow rate does not have any pronounced influence on the N content. Nitrogen incorporation results in an increased optical absorption at 400–600 nm, which is associated with N(2p) energy states that have a higher energy level than the valence band in strontium titanate. The optical band gap energies in the studied N-doped SrTiO3 films are at 3.2–3.3 eV, which is very similar to that of pure strontium titanate (~3.2 eV). Films deposited with NH3 for the RF-plasma exhibit a lower degree of crystallinity and reveal almost no nitrogen incorporation into the crystal lattice.  相似文献   

10.
Implants consisting of drug cores coated with polymeric films were developed for delivering drugs in a controlled manner. The polymeric films were produced using matrix assisted pulsed laser evaporation (MAPLE) and consist of poly(lactide-co-glycolide) (PLGA), used individually as well as blended with polyethylene glycol (PEG). Indomethacin (INC) was used as model drug. The implants were tested in vitro (i.e. in conditions similar with those encountered inside the body), for predicting their behavior after implantation at the site of action. To this end, they were immersed in physiological media (i.e. phosphate buffered saline PBS pH 7.4 and blood). At various intervals of PBS immersion (and respectively in blood), the polymeric films coating the drug cores were studied in terms of morphology, chemistry, wettability and blood compatibility. PEG:PLGA film exhibited superior properties as compared to PLGA film, the corresponding implant being thus more suitable for internal use in the human body. In addition, the implant containing PEG:PLGA film provided an efficient and sustained release of the drug. The kinetics of the drug release was consistent with a diffusion mediated mechanism (as revealed by fitting the data with Higuchi's model); the drug was gradually released through the pores formed during PBS immersion. In contrast, the implant containing PLGA film showed poor drug delivery rates and mechanical failure. In this case, fitting the data with Hixson-Crowell model indicated a release mechanism dominated by polymer erosion.  相似文献   

11.
The melting and recrystallization of nylon-6,10 thin films immersed in an aqueous solution of calcium chloride were investigated by DSC measurements. The crystal length, ζ, was determined as a function of the melting peak temperature, T m . The end surface free energy of nylon-6,10 crystals used for the ζT m conversion was derived thermodynamically. For films of 0.01 mm thickness, the original length of ζ (=7.6 structural units) at T m decreased step by step with increasing immersion time by the length near the structural unit (2.24 nm) per step. However, the suppression of the recrystallization after melting of the original crystals formed during the first cooling by the adsorbed calcium ions did not occur completely, even for films immersed for 30~60 min at 50°C.  相似文献   

12.
Polymeric micelles are attractive nanocarriers for hydrophobic drug molecules such as the kinase inhibitor dactolisib. Two different poly(ethylene glycol)–poly(acrylic acid) (PEG‐b‐PAA) block‐copolymers are synthesized, PEG(5400)‐b‐PAA(2000) and PEG(10000)‐b‐PAA(3700), respectively. Polymeric micelles are formed by self‐assembly once dactolisib is conjugated via the ethylenediamine platinum(II) linker (Lx) to the PAA block of the block copolymers. Dactolisib micelles with dactolisib loading content of 17% w/w show good colloidal stability and display sustained release of Lx‐dactolisib over 96 h in PBS at 37 °C, while media containing reagents that compete for platinum coordination (e.g., glutathione (GSH) or dithiothreitol (DTT)) effectuate release of the parent inhibitor dactolisib at similar release rates. Dactolisib/lissamine‐loaded micelles are internalized by human breast adenocarcinoma cells (MCF‐7) in a dose and time‐dependent manner as demonstrated by confocal microscopy. Dactolisib‐loaded micelles inhibit the PI3K/mTOR signaling pathway at low concentrations (400 × 10?9 m ) and exhibit potent cytotoxicity against MCF‐7 cells with IC50 values of 462 ± 46 and 755 ± 75 × 10?9 m for micelles with either short or longer PEG‐b‐PAA block lengths. In conclusion, dactolisib loaded PEG‐b‐PAA micelles are successfully prepared and hold potential for nanomedicine‐based tumor delivery of dactolisib.  相似文献   

13.
Thin films of blend polymer electrolytes comprising poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) (PVP) complexed with ammonium thiocyanate (NH4SCN) salt in different compositions have been prepared by solution casting technique using distilled water as solvent. The prepared films have been investigated by different experimental techniques. The complexation of these films has been studied by FTIR spectroscopy. The increase in amorphousness of the films with increase in NH4SCN content has been confirmed by XRD analysis. The addition of ammonium thiocyanate salt to PVA-PVP polymer blend shows a shift in Tg of the blend. The effect of salt concentration and temperature on the ionic conductivity of the polymer blend films has been analyzed using AC impedance spectroscopy. The maximum conductivity of 6.85 × 10?4 S cm?1 at room temperature has been observed for the blend with 50 mol% PVA-50 mol% PVP complexed with 40 mol% NH4SCN. The activation energy has been found to be minimum (0.24 eV) for this sample. Wagner’s polarization technique shows that the charge transport in these blend films is predominantly due to ions. Using the highest conductivity blend polymer electrolyte, a proton battery has been fabricated and its discharge characteristics have been studied.  相似文献   

14.
Small-angle X-ray scattering was used to study the mixture of C12E5 (pentaethylene glycol monododecyl ether)/H2O/n-decane microemulsion and polyethylene glycol (PEG). The size, shape and the structure factor of the microemulsion were investigated by adding the polymer (PEG) to the mixture. Attractive depletion potential was induced between the microemulsion droplets by the non-adsorb polymer. The range and strength of the attractive potential were changed by varying the molecular weight and concentration of PEG. The forward scattering, S(0), of the spherical microemulsion, declined gradually as the polymer concentration decreased. For PEG with the molecular weight of Mn = 285?315, the microemulsion morphology remained spherical, but the main peak of the structure factor moved towards a bigger q. When PEG with molecular weights of Mn = 2200 and Mn = 6000 were used, a shape transition from spherical to cylindrical was induced in line with increasing polymer concentration.  相似文献   

15.
We investigate the influence of the pyrazole content on the polyvinylidene fluoride (PVDF)/KI/I2 electrolytes for dye-sensitized solar cells (DSSCs). The solid polymer electrolyte films consisting of different weight percentage ratios (0 20, 30, 40, and 50 %) of pyrazole doped with PVDF/KI/I2 have been prepared by solution casting technique using N,N-dimethyl formamide (DMF) as a solvent. The as-prepared polymer electrolyte films were characterized by various techniques such as Fourier transform infrared spectroscopy (FT-IR spectroscopy), differential scanning calorimetry (DSC), X-ray diffractometer (XRD), alternate current (AC)-impedance analysis, and scanning electron microscopy (SEM). The 40 wt% pyrazole-PVDF/KI/I2 electrolyte exhibited the highest ionic conductivity value of 9.52?×?10?5 Scm?1 at room temperature. This may be due to the lower crystallinity of PVDF and higher ionic mobility of iodide ions in the electrolyte. The DSSC fabricated using this highest ion conducting electrolyte showed an enhanced power conversion efficiency of 3.30 % under an illumination of 60 mW/cm2 than that of pure PVDF/KI/I2 electrolyte (1.42 %).  相似文献   

16.
The studies on solid polymer electrolyte (SPE) films with high ionic conductivity suitable for the realization of all solid-state Na-ion cells? form the focal theme of the work presented in this paper. The SPE films are obtained by the solution casting technique using the blend solution of poly (ethylene oxide) (PEO) with ethylene carbonate (EC) and propylene carbonate (PC) and complexed with sodium nitrate. Structural and thermal studies of SPE films are done by XRD, FTIR spectroscopy, and TGA techniques. Surface morphology of the films is studied using the FESEM. The ionic conductivity of SPE films is determined from the electrochemical impedance spectroscopy studies. For the SPE film with 16 wt% of NaNO3 used for reacting with the polymer blend of PEO with EC and PC, the ionic conductivity obtained is around 1.08 × 10?5 S cm?1. Addition of the Al2O3 as the filler material is found to enhance the ionic conductivity of the SPE films. The studies on the Al2O3 modified SPE film show an ionic conductivity of 1.86 × 10–4 S cm?1, which is one order higher than that of the SPE films without the filler content. For the SPE film dispersed with 8 wt% of Al2O3, the total ion transport number observed is around 0.9895, which is quite impressive from the perspective of the applications in electrochemical energy storage devices. From the cyclic voltammetry studies, a wide electrochemical stability window up to 4 V is observed, which further emphasizes the commendable electrochemical behavior of these SPE films.  相似文献   

17.
Poly(ethylene glycol)/poly(2-acrylamido-2-methyl-1-propane sulfonic acid) (PEG/PAMPS) with a transparent appearance were prepared in the presence of ammonium persulfate (APS) as an initiator at 70 °C for 24 h. PEG/PAMPS-based polymer gel electrolytes in a motionless and uniform state were obtained by adding the required amount of liquid electrolytes to a dry PEG/PAMPS polymer. Liquid electrolytes include organic solvents with high boiling points (-1-methyl-2-pyrrolidone (NMP) and γ-butyrolactone (GBL)) and a redox couple (alkali metal iodide salt/iodine). The optimized conditions for PEG/PAMPS-based gel electrolytes based on the salt type, the concentration of alkali metal iodide salt/iodine, and solvent volume ratio were determined to be NaI, 0.4 M NaI/0.04 M I2, and NMP:GBL (7:3, v/v), respectively. The highest ionic conductivity and the liquid electrolyte absorbency were 2.58 mS cm?1 and 3.6 g g?1 at 25 °C, respectively. The ion transport mechanism in both the polymer gel electrolytes and liquid electrolytes is investigated extensively, and their best fits with respect to the temperature dependence of the ionic conductivity are determined with the Arrhenius equation.  相似文献   

18.
De-Jiang Qi  Hong-Qiang Ru  Xiao-Guo Bi 《Ionics》2013,19(11):1573-1578
A novel solid-state composite polymer electrolyte (CPE), based on a polymer, poly(ethylene oxide) (PEO), alkali metal salts, and NaY molecular sieve powders with a small amount of low molecular weight plasticizer, ethylene carbonate (EC) is investigated. (PEO)16LiClO4 polymer metal salt complexes with 5 wt% EC, and different content of NaY are prepared by the solution casting technology. The crystallization characteristic, surface morphology, and ionic conductivity of the CPE systems are studied using X-ray diffractometer (XRD) analysis, scanning electron microscopy (SEM), energy dispersive spectrometer, and impedance spectroscopy. It is found that NaY incorporation has a beneficial effect on the enhancement of ionic conductivity, increasing two orders of magnitude. XRD spectra show that the NaY has a major influence on the crystallization process of polymer matrix. By incorporating NaY, the crystallinity degree of PEO matrix obviously decreases. SEM images show a dramatic modification of surface morphology, the surface spherulites of polymer matrix disappear, and ultra-branched and cross-linked framework structure forms, which play an important role in ion transport and enhancing the tensile strength (TS). The TS is achieved 2.12 MPa with the content of 35 wt% NaY, far higher than the 0.17 MPa with (PEO)16LiClO4–5 wt% EC. In addition, it is demonstrated for the first time that EC affects the network structure of the molecular sieve and leads to exhibit enhanced ionic conductivity of electrolyte maintaining for a long time.  相似文献   

19.
Biodegradable polymer electrolyte comprising the blend of chitosan (CS) and poly(ethylene glycol) (PEG) plasticized with ethylene carbonate and propylene carbonate, as host polymer, and lithium perchlorate (LiClO4), as a dopant, was prepared by solution casting technique. The ionic conductivity has been calculated using the bulk impedance obtained through impedance spectroscopy. The variation of conductivity and dielectric properties has been investigated as a function of polymer blend ratio, plasticizer content and LiClO4 concentration at temperature range of 298–343 K. The DSC thermograms show two broad peaks for CS/PEG blend and increased with increase in the LiClO4 content. The maximum conductivity has been found to be 1.1?×?10?4 S cm?1 at room temperature for 70:30 (CS/PEG) concentration. The electric modulus of the electrolyte film exhibits a long tail feature indicative of good capacitance. The activation energy of all samples was calculated using the Arrhenius plot, and it has been found to be 0.12 to 0.38 eV. A carbon–carbon supercapacitor has been fabricated using this electrolyte, and its electrochemical characteristics and performance have been studied. The supercapacitor showed a fairly good specific capacitance of 47 F?g?1.  相似文献   

20.
Sodium ion conducting solid polymer blend electrolyte thin films have been prepared by using polyvinyl alcohol (PVA)/poly(vinyl pyrrolidone) (PVP) with NaNO3 by solution cast technique. The prepared films were characterized by various methods. The complexation of the salt with the polymer blend was identified by X-ray diffraction (XRD) and Fourier transforms infrared spectroscopy (FTIR), Differential scanning calorimetry was used to analyze the thermal behavior of the samples, and the glass transition temperature is low for the highest conducting polymer material. The scanning electron microscopy gives the surface morphology of the polymer electrolytes. The frequency and temperature dependent of electrical conductivities of the films were studied using impedance analyzer in the frequency range of 1 Hz to 1 MHz. The highest electrical conductivity of 50PVA/50PVP/2 wt% NaNO3 concentration has been found to be 1.25 × 10?5 S cm?1 at room temperature. The electrical permittivity of the polymer films have been studied for various temperatures. The transference number measurements showed that the charge transport is mainly due to ions than electrons. Using this highest conducting polymer electrolyte, an electrochemical cell is fabricated and the parameters of the cells are tabulated.  相似文献   

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