Structural and electrical characterizations of 50:50 PVA:starch blend complexed with ammonium thiocyanate

The present work deals with the preparation and characterization of polymer blend electrolyte films. Glutaraldehyde is used as a cross-linker to cross-link polymers polyvinyl alcohol (PVA) and starch for the proper film formation. Structural characterizations such as X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) have been performed. X-ray diffraction is done to investigate the amorphous nature of the sample. FTIR study confirms about the complexation of salt with the polymer and interaction of thiocyanate ion with the polymer matrix. Electrical characterizations were done using impedance spectroscopy. DC and AC ionic conductivity was obtained at varying salt concentration in the films which shows maximum ionic conductivity of the polymer electrolyte containing 30 wt% of salt content. The AC conductivity behaviour of the polymer electrolyte follows Jonscher’s power law. Dielectric parameters such as dielectric constant, dielectric loss and loss tangent have been determined. Relaxation time is obtained and decreases to lower value with the increase in the salt concentration in the polymer electrolyte.     

Synthesis,characterization, conductivity and sensor application study of polypyrrole/silver doped nickel oxide nanocomposites

Conducting polymer composites of polypyrrole (PPy) and silver doped nickel oxide (Ag-NiO) nanocomposites were synthesised by in situ polymerisation of pyrrole with different contents of Ag-NiO nanoparticles. The formation of nanocomposites were studied by Fourier transform infrared (FTIR) and UV–vis spectroscopy, field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and AC and DC conductivity measurements. The sensitivity of ammonia gas through the nanocomposite was analysed with respect to different contents of nanoparticles. Spectroscopic studies showed the shift in the absorption bands of polymer nanocomposite than that of pure PPy indicating the strong interaction between the nanoparticles and polymer chain. FESEM revealed the uniform dispersion of nanoparticles with spherically shaped metal oxide particles in PPy matrix. The XRD pattern indicated a decrease in amorphous domain of PPy with increase in loading of nanoparticles. The higher thermal stability and glass transition temperature of polymer nanocomposites than that of pure PPy were revealed from the TGA and DSC respectively. The dielectric properties, DC and AC conductivity of nanocomposites were much higher than PPy and these electrical properties increases with the loading of nanoparticles. The nanocomposites showed an enhancement in sensitivity towards ammonia gas detection than PPy.     

Synthesis and characterization of dextrin-based polymer electrolytes for potential applications in energy storage devices

An attempt has been made to synthesise a new proton conducting polymer electrolyte using the biopolymer dextrin doped with ammonium thiocyanate salts using solution casting technique. The complexation has been studied using X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The differential scanning calorimetry (DSC) thermograms of dextrin with NH₄SCN showed that T_g value increases with respect to the increase of NH₄SCN concentration. The electrical conductivity was measured using AC impedance analyser which showed that ionic conductivity increases with increase in salt concentration up to 40%. Transference number measurement was carried out to investigate the nature of the charge transport species in the polymer electrolyte. Surface morphology of the electrolytes was determined using scanning electron microscope (SEM) studies, and the chemical composition of the elements present was determined using EDAX. The proton battery was constructed with the highest conducting polymer electrolyte Dex-40%NH₄SCN and its open circuit voltage with load were carried out.     

Structural, vibrational and electrical characterization of PVA-NH4Br polymer electrolyte system

Polymer electrolyte based on PVA doped with different concentrations of NH₄Br has been prepared by solution casting technique. The complexation of the prepared polymer electrolytes has been studied using X-ray diffraction (XRD) and Fourier transform infra red (FTIR) spectroscopy. The maximum ionic conductivity (5.7×10⁻⁴ S cm⁻¹) has been obtained for 25 mol% NH₄Br-doped PVA polymer electrolyte. The temperature dependence of ionic conductivity of the prepared polymer electrolytes obeys Arrhenius law. The ionic transference number of mobile ions has been estimated by dc polarization method and the results reveal that the conducting species are predominantly ions. The dielectric behavior of the polymer electrolytes has been analyzed using dielectric permittivity and electric modulus spectra.     

Synthesis and study of optical and electrical characteristics of a hybrid structure of single wall carbon nanotubes and silver nanoparticles

Ag nanoparticles of average size 20 nm have been deposited on SWCNT surfaces following a very lucid wet chemical process. The SWCNT/Ag nanohybrid material has been characterized using scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), X-ray diffraction (XRD) analysis and Raman spectroscopy. Both optical and electrical properties of the hybrid have been studied. The hybrid material has been synthesized at 60 °C and treated to higher temperatures. About three-fold increase in photoluminescence (PL) emission intensity has been achieved when the hybrid sample has been treated to 500 °C. DC conductivity at varying temperatures from 77–473 K has been studied. The conductivity of Ag-decorated SWCNTs increased up to 1.76 times of that of pristine SWCNT at a low temperature of 180 K. This hybrid material can find wide application as conducting filler in polymer composite which other filler materials seldom possess.     

Electrical,optical, and structural characterization of polymer blend (PVC/PMMA) electrolyte films

Ion-conducting solid polymer blend electrolytes based on polyvinyl chloride (PVC)/poly methyl methacrylate (PMMA) complexed with sodium perchlorate (NaClO₄) were prepared in various concentrations by solution cast technique. The features of complexation of the electrolytes were studied by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. DC conductivity of the films was measured in the temperature range 303–398 K. Transference number measurements were carried out to investigate the nature of charge transport in the polymer blend electrolyte system. The electrical conductivity increased with increasing dopant concentration, which is attributed to the formation of charge transfer complexes. The polymer complexes exhibited Arrhenius type dependence of conductivity with temperature. In the temperature range studied, two regions with different activation energies were observed. Transference number data showed that the charge transport in this system is predominantly due to ions. Optical properties like absorption edge, direct band gap, and indirect band gap were estimated for pure and doped films from their optical absorption spectra in the wavelength region 200–600 nm. It was found that the energy gap and band edge values shifted to lower energies on doping with NaClO₄ salt. Paper presented at the Third International Conference on Ionic Devices (ICID 2006), Chennai, Tamil Nadu, India, Dec. 7–9, 2006.     

Effect on Structure,Processability, and Conductivity of Poly(m-aminophenol) of the Initial Acidity/Basicity of the Polymerization Medium

Poly(m-aminophenol) was synthesized chemically from aqueous solutions of the monomer meta-aminophenol (mAP) in the initially acidic or basic medium by using ammonium persulfate as an oxidant. The polymer (PmAPA) synthesized in initially aqueous HCl medium was insoluble in organic solvents even after dedoping, while the polymer (PmAPB) synthesized in initially aqueous NaOH solution was found to be soluble in high pH water, dimethyl sulfoxide (DMSO), and dimethylformamide. It was possible to obtain a stable, free-standing film from the DMSO solution of PmAPB but, due to insolubility and infusibility, film casting was not possible for PmAPA. The synthesized polymers were characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analyses, X-ray diffraction spectroscopy, and four-probe DC electrical conductivity. A ladder-type structure was formed during the chemical polymerization of mAP in aqueous HCl, while a hydroxyl derivative of polyaniline was obtained in aqueous NaOH. The conductivity of sulfuric acid-doped PmAPB was 10⁴ times higher than that of in situ HCl-doped PmAPA. An explanation of the difference in properties of both polymers is given based on molecular modeling.     

Tamarind seed polysaccharide (TSP)-based Li-ion conducting membranes

Polysaccharide-based biopolymers have gained much attention in electrochemical devices recently. Tamarind seed polysaccharide (TSP) is a biopolymer obtained from the extract of tamarind seed. It is used as thickening and gelling agent in food and textile industries. There are no works in polymer electrolytes based on TSP in lithium-ion conducting membranes. A pure TSP membrane has been prepared by dissolving 1 g of TSP in distilled water by using solution-casting technique. The prepared biopolymer membranes are subjected to Fourier transform infrared (FTIR), X-ray diffraction (XRD), and AC-impedance techniques. FTIR analysis has been conducted to observe the possible interaction between the polymer and lithium salt based upon the changes in wave numbers of the peaks. The nature of the membrane (crystalline or amorphous) has been revealed by XRD. The electrical properties of the membranes have been analyzed by AC-impedance spectroscopy. The maximum ionic conductivity for the salt-doped membrane 1 g TSP:0.4 g lithium bromide (LiBr) has been found to be 4.83 × 10^?4 S cm^?1. The primary lithium-ion battery has been constructed using the best conductivity membrane, and the open circuit voltage (OCV) has been observed as 1.63 V.     

Optical absorption and spectrophotometric studies on the optical constants and dielectric of poly (o-toluidine) (POT) films grown by spin coating deposition

In this work, a poly(o-toluidine) “POT” was synthesized by chemical oxidative polymerization method in aqueous media. High uniform and good adhesion thin films of POT have been successfully deposited by the spin coating technique. The films were characterized by X-ray diffraction (XRD) and Fourier transforms infrared (FTIR) spectroscopy. The XRD pattern of the POT shows the semi-crystalline nature of the films. FTIR studies show the information of functional groups in POT. The optical transmittance and reflectance of POT film was measured in the 200–2500 nm wavelength range. The absorption coefficient analysis shows that the optical band gaps of POT film are direct allowed transition band gaps with 1.2 and 2.6 eV. Other optical absorption parameters such as extinction molar coefficient, oscillator strength and electric dipole strength were also calculated. The dispersion parameters were determined and discussed based on the single oscillator model. According to the analysis of dispersion curves some important parameters such as dispersion energy (E_d), oscillator energy (E_o), high frequency dielectric constant ₍ε_∞) and lattice dielectric constant (ε_L) were also evaluated. Discussion of the obtained results and their comparison with the previous published data were also given. The obtained desirable results of POT thin film can be useful for the optoelectronic applications.     

Synthesis and characterization of Cr doped CdS nanoparticles stabilized with polyvinylpyrrolidone

Undoped and Cr (2 and 4 at.%) doped CdS nanoparticles were synthesized in aqueous solution by simple chemical co-precipitation method using polyvinylpyrrolidone (PVP) as stabilizer. The prepared nanoparticles were examined using X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDAX), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy (DRS) and Fourier transform infrared spectroscopy (FTIR). XRD pattern of the nanoparticles showed cubic zincblende phase with the particle size of the order of 3-4 nm, which was in good agreement with the results obtained from TEM studies. The EDAX analysis confirmed that Cd, Cr and S elements were present in the samples and the variations between the target and actual compositions were microscopic. UV-vis DRS spectra of the samples exhibited decrease in the band gap which further attests the incorporation of Cr into CdS nanoparticles. FTIR studies revealed that the undoped as well as Cr doped CdS nanoparticles were capped by polyvinylpyrrolidone.     

Proton-conducting polymer electrolyte based on PVA-PAN blend doped with ammonium thiocyanate

Blending of polymers is one of the most useful methods for modulating the conductivity of solid polymer electrolytes. Blend polymer electrolytes have been prepared with polyvinyl alcohol (PVA)-polyacrylonitrile (PAN) blend doped with ammonium thiocyanate with different concentrations by solution casting technique, using dimethyl formamide (DMF) as the solvent. The prepared electrolytes are characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), nuclear magnetic resonance (NMR), ultraviolet (UV), and ac impedance measurement techniques. The increase in amorphous nature of the blend polymer electrolyte by the addition of salt is confirmed by XRD analysis. The complex formation between the polymers and the salt has been confirmed by FTIR analysis. The thermal behavior has been examined using DSC and TGA. The maximum conductivity has been found to be 2.4?×?10^?3 S cm^?1 for 92.5PVA/7.5PAN/25 % NH₄SCN sample at room temperature. The temperature dependence of conductivity has been studied with the help of Arrhenius plot, and the activation energies are calculated. The proton conductivity is confirmed by dc polarization measurement technique. ¹H NMR studies reveal the presence of protons in the sample. A proton battery is constructed with the highest conducting sample, and its open circuit voltage is measured to be 1.2 V     

Investigations on the effect of complexation of NaF salt with polymer blend (PEO/PVP) electrolytes on ionic conductivity and optical energy band gaps

Sodium ion conducting polymer blend electrolyte films, based on polyethylene oxide (PEO) and polyvinyl pyrrolidone (PVP) complexed with NaF salt, were prepared using solution casting technique. The complexation of the salt with the polymer blend was confirmed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and UV-vis spectroscopy. Electrical conductivity of the films was measured with impedance analyzer in the frequency range of 1 Hz to 1 MHz and in the temperature range of 303-348 K. It was observed that the magnitude of conductivity increased with the increase in the salt concentration as well as the temperature. UV-vis absorption spectra in wavelength region of 200-800 nm were used to evaluate the optical properties like direct and indirect optical energy band gaps, optical absorption edge. The optical band gaps decreased with the increase in Na⁺ ion concentration. This suggests that NaF, as a dopant, is a good choice to improve the electrical properties of PEO/PVP polymer blend electrolytes.     

Effects of Al2O3 nanofiller and EC plasticizer on the ionic conductivity enhancement of solid PEO-LiCF3SO3 solid polymer electrolyte

A solid polymer electrolyte (SPE) is synthesized by solution casting technique. The SPE uses poly(ethylene oxide) PEO as a host matrix doped with lithium triflate (LiCF₃SO₃), ethylene carbonate (EC) as plasticizer and nano alumina (Al₂O₃) as filler. The polymer electrolytes are characterized by Impedance Spectroscopy (IS) to determine the composition of the additive which gives the highest conductivity for each system. At room temperature, the highest conductivity is obtained for the composition PEO-LiCF₃SO₃-EC-15%Al₂O₃ with a value of 5.07 10^− 4 S/cm. The ionic conductivity of the polymer electrolytes increases with temperature and obeys the Arrhenius law. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) studies indicate that the conductivity increase is due to an increase in amorphous content which enhances the segmental flexibility of polymeric chains and the disordered structure of the electrolyte. Fourier transform infrared spectroscopy (FTIR) spectra show the occurrence of complexation and interaction among the components. Scanning electron microscopy (SEM) images show the changes morphology of solid polymer electrolyte.     

Effect of lithium thiocyanate addition on the structural and electrical properties of biodegradable poly(ε-caprolactone) polymer films

Polymer electrolyte films of biodegradable poly(ε-caprolactone) (PCL) doped with LiSCN salt in different weight ratios were prepared using solution cast technique. The effect of crystallinity and interaction between lithium ions and carbonyl groups of PCL on the ionic conduction of PCL:LiSCN polymer electrolytes was characterized by X-ray diffraction (XRD), optical microscopy, Fourier transform infrared spectroscopy (FTIR) and AC impedance analysis. The XRD results revealed that the crystallinity of the PCL polymer matrix decreased with an increase in LiSCN salt concentration. The complexation of the salt with the polymer and the interaction of lithium ions with carbonyl groups of PCL were confirmed by FTIR. The ionic conductivity was found to increase with increasing salt concentration until 15 wt% and then to decrease with further increasing salt concentration. In addition, the ionic conductivity of the polymer electrolyte films followed an Arrhenius relation and the activation energy for conduction decreased with increasing LiSCN concentration up to 15 wt%. UV–vis absorption spectra were used to evaluate the optical energy band gaps of the materials. The optical energy band gap shifted to lower energies with increasing LiSCN salt concentration.     

Investigations on the electrical and structural properties of polyaniline doped with camphor sulphonic acid

Polyaniline is chemically synthesised and doped with camphor sulphonic acid. FTIR studies carried out on these samples indicate that the aromatic rings are retained after polymerisation. The percentage of crystallinity for polyaniline doped with camphor sulphonic acid has been estimated from the X-ray diffraction studies and is around 56% with respect to polyaniline emeraldine base. The change in dielectric permittivity with respect to temperature and frequency is explained on the basis of interfacial polarisation. AC conductivity is evaluated from the observed dielectric permittivity. The values of AC and DC conductivity and activation energy are calculated. The activation energy values suggested that the hopping conduction is the prominent conduction mechanism in this system.     

Synthesis and characterization of novel nano-size polyreactive yellow 107

The reactive yellow 107 was polymerized by chemical oxidation method using potassium persulfate. The polymer was characterized by UV-VIS and Fourier transform infrared spectroscopy (FTIR) spectral studies. The peaks at 2,922 and 2,852 cm⁻¹ in the FTIR spectrum of polyreactive yellow 107 are assigned to the symmetric and asymmetric stretching vibrations of CH₂. The peak observed at 1,583 cm⁻¹ for polyreactive yellow 107 may be assigned to the stretching vibration of C=O, N=N, and C=C, 1,347 cm⁻¹ stretching vibration of C–N. The stretching vibrations of sulfone and sulfonic acid of S=O groups show a strong broad peak at 1,091 and 1,051 cm⁻¹. The conductivity of the polymer was determined to be 5.57 × 10⁻⁵ S cm⁻¹. The solubility of the chemically polymerized powder was ascertained and polyreactive yellow 107 showed good solubility in N,N-dimethyl formamide and dimethyl sulfoxide. The X-ray diffraction studies revealed the formation of nano-sized (84 nm) crystalline polymer. Using X-ray diffraction, behavior strain and dislocation density was also calculated. Scanning electron microscope analysis showed uniform crystalline nature of the polymer (200 nm). The thermogravimetric analysis, differential thermal analysis, and differential scanning calorimetry studies revealed good thermal stability of the polymer.     

Incorporation of NH4Br in PVA-chitosan blend-based polymer electrolyte and its effect on the conductivity and other electrical properties

Polymer electrolyte system based on poly(vinyl alcohol) (PVA)-chitosan blend doped with ammonium bromide (NH₄Br) has been prepared by solution cast method. Fourier transform infrared (FTIR) spectroscopy analysis confirms the complexation between salt and polymer host. The highest ionic conductivity obtained at room temperature is (7.68?±?1.24)?×?10^?4 S cm^?1 for the sample comprising of 30 wt% NH₄Br. X-ray diffraction (XRD) patterns reveal that PVA-chitosan with 30 wt% NH₄Br exhibits the most amorphous structure. Thermogravimetric analysis (TGA) reveals that the electrolytes are stable until ～260 °C. The conductivity variation can also be explained by field emission scanning electron microscopy (FESEM) study. Dielectric properties of the electrolytes follow non-Debye behavior. The conduction mechanism of the highest conducting electrolyte can be represented by the correlated barrier hopping (CBH) model. From linear sweep voltammetry (LSV) result, the highest conducting electrolyte is electrochemically stable at 1.57 V.     

Incorporation of NH<Subscript>4</Subscript>NO<Subscript>3</Subscript> into MC-PVA blend-based polymer to prepare proton-conducting polymer electrolyte films

Proton-conducting solid polymer blend electrolytes based on methylcellulose-polyvinyl alcohol:ammonium nitrate (MC-PVA:NH₄NO₃) were prepared by the solution cast technique. The structural and electrical properties of the samples were examined by X-ray diffraction (XRD), Fourier transform infrared (FTIR), and electrical impedance (EI) spectroscopy. The shifting and change in the intensity of FTIR bands of the electrolyte samples confirm the complex formation between the MC-PVA polymer blend and the NH₄NO₃ added salt. The observed broadening in the XRD pattern of the doped samples reveals the increase of the amorphous fraction of polymer electrolyte samples. The increase in electrical conductivity of polymer electrolyte samples with increasing salt concentration attributed to the formation of charge-transfer complexes, and to increase in the amorphous domains. A maximum ionic conductivity of about 7.39 × 10^?5 S cm^?1 was achieved at room temperature for the sample incorporating 20 wt% of NH₄NO₃. The DC conductivity of the present polymer system exhibits Arrhenius-type dependence with temperature. The decrease in the values of activation energies with increasing salt concentration indicates the ease mobility of ions. The decrease in dielectric constant with increasing frequency was observed at all temperatures. Optical properties such as absorption edge, optical band gap, and tail of localized state were estimated for polymer blend and their electrolyte films. It was found that the optical band gap values shifted towards lower photon energy from 6.06 to 4.75 eV by altering the NH₄NO₃ salt content.     

Modifications induced by gamma irradiation upon structural,optical and chemical properties of polyamide nylon-6,6 polymer

The effects of gamma rays were studied on the optical, structural and chemical properties of the PA-66 polymer samples. The polymer samples obtained from Goodfellow (Cambridge, UK) were irradiated with gamma rays at various doses ranging from 100 to 1250 kGy. The pristine and gamma rays irradiated samples were characterized by UV–visible (UV–VIS) spectroscopy, X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. UV–VIS shows a shift in absorption toward the visible region for irradiated samples and a decrease in band gap energy (E_g). The XRD analyses show an increase in the crystalline nature of the polymer at higher doses as a result of significant decrease in the peak width of XRD patterns. The FTIR spectra show decrease in intensity and shift of various bands with increase in gamma dose.     

Dielectric and impedance studies of DBSA doped polyaniline/PVC composites

Polyaniline (PANI) was doped with dodecylbenzene sulfonic acid (DBSA) and then mixed with PVC by solution blending method to prepare DBSA doped PANI (PAND)/PVC composites. FTIR spectroscopy indicates the strong dipole–dipole interaction between the individual components of the composites. The ac electrical properties of the synthesized composites were investigated by complex impedance spectroscopy in the frequency range of 0.5–10⁶ Hz at room temperature. Both dielectric loss factor and permittivity increase with the decrease of frequency exhibiting strong interfacial polarization at low frequency. Addition of PAND in PVC reduces the charge trapping centers by increasing the number of conducting channels participating in the relaxation process; hence an increase in conductivity is observed.