Pure Polyethylene Oxide Research Articles

Optical Dielectric Loss as a Novel Approach to Specify the Types of Electron Transition: XRD and UV-vis as a Non-Destructive Techniques for Structural and Optical Characterization of PEO Based Nanocomposites.

The structure and optical properties of polyethylene oxide (PEO) doped with tin titanate (SnTiO3) nano-filler were studied by X-ray diffraction (XRD) and UV-Vis spectroscopy as non-destructive techniques. PEO-based composed polymer electrolytes inserted with SnTiO3 nano-particles (NPs) were synthesized through the solution cast technique. The change from crystalline phase to amorphous phase of the host polymer was established by the lowering of the intensity and broadening of the crystalline peaks. The optical constants of PEO/SnTiO3 nano-composite (NC), such as, refractive index (n), optical absorption coefficient (α), dielectric loss (εi), as well as dielectric constant (εr) were determined for pure PEO and PEO/SnTiO3 NC. From these findings, the value of n of PEO altered from 2.13 to 2.47 upon the addition of 4 wt.% SnTiO3NPs. The value of εr also increased from 4.5 to 6.3, with addition of 4 wt.% SnTiO3. The fundamental optical absorption edge of the PEO shifted toward lower photon energy upon the addition of the SnTiO3 NPs, confirming a decrement in the optical band gap energy of PEO. The band gap shifted from 4.78 eV to 4.612 eV for PEO-doped with 4 wt.% SnTiO3. The nature of electronic transitions in the pure and the composite material were studied on the basis of Tauc’s model, while optical εi examination was also carried out to calculate the optical band gap.

Determination of Hansen solubility parameters of halloysite nanotubes and prediction of its compatibility with polyethylene oxide

Halloysite nanotubes are extensively studied natural tubular clay mineral that has many potentially important uses in different industrial fields. In this paper, the dispersion behavior of halloysite nanotubes (HNTs) in 22 solvents of different polarities was investigated by dynamic light scattering (DLS) and ultraviolet spectrophotometer (UV). The result revealed that HNTs can be dispersed in solvents with high polar and hydrogen bond component parameters, and the best dispersions were achieved in N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), ethanol (EtOH), and acetonitrile (ACN). Hansen solubility parameters (HSPs) of HNTs were approximately determined of δd = 16.8 MPa1/2, δp = 12.6 MPa1/2 and δh = 17.4 MPa1/2 based on the dispersion state tests. The HSPs of polyethylene oxide (PEO) were further estimated using the group contribution method to predict the compatibility of HNTs and PEO employing HSP theory. The SEM images of the PEO/ HNTs composites with different HNTs content showed that the HNTs were well dispersed in the PEO matrix. Meanwhile, the PEO/HNTs composites exhibited enhanced thermal stability compared to the pure PEO. The results suggested there existed good compatibility between HNTs and PEO and confirmed the usefulness of this approach.

Conductivity of PEO/PLA Doped Liquid Crystal Ionomer Solid Polymer Electrolyte in Mesomorphic Range

A novel polyethylene oxide (PEO)/polylactic acid (PLA) solid polymer electrolyte (SPE) doped with Liquid crystal ionomer (LCI) was prepared by automatic scraping membrane technology and the liquid crystal property of LCI was proposed as an effective strategy to improve the conductivity. The highest conductivity of the SPE with 0.5 wt% LCI achieve a value of 2.19 × 10−4 S/cm at 17 °C which is approximately four orders of magnitude higher than that of the original PEO solid polymer electrolyte, conductivity at room temperature is 10−7–10−8 S/cm. This is because the crystallinity is reduced by 25.3% compared to the pure PEO host. Differential Scanning Calorimetry (DSC) and polarizing microscope (POM) characterize the structure and properties of LCI. Electrochemical Impedance Spectroscopy (EIS) shows that the conductivity of the polymer electrolyte with 0.5 wt% LCI increased abruptly at 35 °C as the temperature is higher than Tg of LCI, reaching 6.37 × 10−4 S/cm which is 191% higher than that at 17 °C. There ionic conductivity has been improved extremely by continuous channel for efficient ion transportation, especially at the microtherm. And this change is greater at the elevated temperature regions, in line with the VTF equation. In summary, LCI’s liquid crystal performance can be used as an effective strategy to improve the low temperature conductivity of SPE.

Conductive Bicomponent Fibers Containing Polyaniline Produced via Side-by-Side Electrospinning.

In this study, using a barbed Y-connector as the spinneret, camphoric acid (CSA) doped polyaniline (PANI) and polyethylene oxide (PEO) were electrospun into side-by-side bicomponent fibers. Fiber mats obtained from this side-by-side spinneret were compared with those mats electrospun from blended PEO and PANI in terms of fiber morphology, electrical conductivity, thermal stability, mechanical properties, and relative resistivity under tensile strain. The influence of different content ratio of insulating PEO (3/4/5 w/v% to solvent) and conductive PANI-CSA (1.5/2.5/3.5 w/v% to solvent) on the abovementioned properties was studied as well. Results showed that this side-by-side spinning was capable of overcoming the poor spinnability of PANI to produce fibers with PEO carrying PANI on the surface of the bicomponent fibers, which demonstrated higher electrical conductivity than blends. Although the addition of PANI deteriorated mechanical properties for both side-by-side and blended fibers when compared to the pure PEO fibers, the side-by-side fibers showed much better fiber strength and elongation than blends. In addition, the superior ductility and decent relative electrical resistivity of the side-by-side fibers imparted them great potential for flexible sensor applications.

Structural, thermal, morphological and optical properties of PEO filled with biosynthesized Ag nanoparticles: New insights to band gap study

Abstract In this study new insight to band gap study was presented. The solution cast technique was employed in the present study for the preparation of polymer composites based on polyethylene oxide (PEO), while silver nanoparticles (AgNPs) were synthesized via the green chemistry method. Reduction of silver ions to metallic silver particles was achieved with environmentally friendly and free-of-cost quince leaves. Correlation was established between the outcomes of band gap investigation and XRD analysis. Preparation of PEO:Ag polymer composites involved addition of suspended AgNPs in various concentrations to PEO solution. PEO:Ag composite films were found to be associated with broad absorption peaks due to plasmonic metallic silver particles at 320–780 nm wavelength. The sample incorporating 15 mL of suspended AgNPs is more amorphous, according to the outcomes of XRD analysis. Meanwhile, the FTIR analysis provided categorical evidence for complexation occurring between AgNPs and PEO matrix. The shifting of FTIR bands of PEO:Ag composite films compared to pure PEO is an evidence for interaction among the composite components. The sample melting point was estimated via a thermal investigation. The outcomes of FTIR and XRD analyses were supported by the morphological study. Pure PEO was found to be associated with interconnected spherulites. At 15 mL of AgNPs, there was a decrease in spherulite size, while at 30 mL AgNPs, larger-sized spherulites appeared. Estimation of the optical band gaps of the films required an in-depth investigation of their optical properties. The outcomes of absorption edge study and band gap analysis emphasized that optical dielectric loss is a skilled method for band gap study. Based on theoretical background and experimental approaches, deep insights into band gap behaviour and materials structure are documented.

Transport and Diffusion Properties in PEO-BaCl2 Polymer Electrolytes for Battery Applications

Barium chloride (BaCl2) doped polyethylene oxide (PEO) based solid polymer electrolyte (SPE) films are prepared using solution cast technique. Impedance analysis reveals that the ionic conductivity of pure PEO polymer enhances with frequency as well as BaCh concentrations, the maximum ac - ionic conductivity (1.09 × 10−4 Scm1) is observed at 10 wt% BaCl2 doped PEO polymer electrolyte films at high frequency. The temperature dependent conductivity studies were carried out for 10 wt% of BaCl2 concentration, here the maximum dc - ionic conductivity achieved is 1.44 × 10−2 Scm−1 at 333K temperature. From transport properties, it is observed that the transference number of ions in the polymer electrolyte system is 0.98 and electronic transference number are 0.019. Hence ions are the majority charge carriers than the electrons in BaCl2 doped PEO based solid polymer electrolytes. Diffusion coefficient study confirms the cations play a major role for the conduction mechanism with in the electrolyte system.

Characteristic studies on PEO-based thin nanocomposite polymer electrolytes

A novel polyethylene oxide (PEO)–based sodium conducting thin nanocomposite polymer electrolyte (NPE) is prepared using solution casting technique. The concentration of the salt has been varied and for EO:Na of 40:1, the room temperature electrical conductivity is found to be increased by two orders of magnitude relative to the pure PEO (σ298 K = 2.8 × 10−9 S cm−1). Ionic conductivity and thermal behavior of PEO40NaC12H25SO4 complex have been investigated with different levels of loading of nano-sized MgO powder whereas the complexation has been confirmed by X-ray diffraction and Fourier transform infrared spectroscopic analyses. Structural, thermal, and morphology results have also clearly demonstrated the reduction of crystallinity of the composite polymer electrolyte by the addition of fine MgO nanoparticles. The nanocomposite polymer electrolyte while employed in the fabrication of electrochemical cell has yielded an open-circuit voltage (OCV) of 2.35 V and short-circuit current (SCC) of 412 μA. On incorporation of MgO nanoparticles, it was observed that there is a further enhancement in the conductivity. The room temperature ionic conductivity of PEO–NaC12H25SO4–MgO is relatively high and stable, indicating that it is a promising electrolyte for several thin solid-state energy devices.

Efficient Inverted Polymer Solar Cells with ITO Cathode Modified by Zinc Oxide and Polyethylene Oxide Bilayers

For inverted polymer solar cells (PSCs), zinc oxide (ZnO) with various advantages are typically used as cathode buffer layer, but the existing surface traps/detects of ZnO layer obviously restrict device performance. In this work, the authors introduce polyethylene oxide (PEO) with high molecular weight of 300 thousands to modify the surface of ZnO layer on ITO cathode for inverted PSCs, where PEO possesses the particular advantages of easy accessibility and low cost. Compared with the ITO modified by pure ZnO and PEO layer, the ITO modified by ZnO/PEO bilayers shows the similarly good transparency, the lowest work function, the best surface morphology, and contact property. ZnO/PEO bilayers can provide the optimal energy alignment and interface contact between ITO and active layer, and efficiently eliminate the surface defects of ZnO layer. Therefore, the ITO/ZnO/PEO-based device exhibits the best photovoltaic performance with the PCE of 9.57% compared to the ITO/ZnO-based device (8.42%) and the ITO/PEO-based device (8.16%). The impressive results suggest that ZnO/PEO bilayers should be promising cathode buffer layer for high-performance inverted PSCs.

Identification of relaxation processes in pure polyethylene oxide (PEO) films by the dielectric permittivity and electric modulus formalisms

The ac‐impedance of bulk‐like films of pure polyethylene oxide (PEO) polymer was measured as a function of frequency f in the range 0.1 to 107 Hz at various constant temperatures T (155 − 330 K). The as‐measured data were analyzed by electric permittivity and modulus formalisms to unveil which dielectric and conductive relaxation processes were responsible for their relaxation behavior below/above glass transition temperature Tg of pure PEO polymer. At T > Tg, none of the α‐, β‐, or γ‐relaxations could be inferred for studied pure PEO films from frequency variation of measured imaginary part ε′′(f, T) of complex dielectric permittivity , as low‐frequency losses masked real dielectric contribution to the measured ε′′(f, T) at low frequencies and high temperatures. However, at T < Tg, a broad, relaxation process has been observed in the high‐frequency part of their isothermal ε′′(f, T) − f spectra, which can be related to the β‐ or γ‐dielectric relaxation process. Nonlinear regressions of the measured ε′′(f, T) − f data for T < Tg yielded moral fits to a simple addition of a Havriliak‐Negami function, and a Bergman‐loss Kohlrausch‐Williams‐Watts‐type function, with the relaxation time τmax(T) obtained from Havriliak‐Negami‐fitting parameters, was found to follow a thermally activated Arrhenius‐like relaxation behavior. Conversely, representation of the imaginary part M′′(f, T > Tg) − f spectra of complex electric modulus was found to depict 2 overlapped relaxation processes, which were detached well by a nonlinear regression of a simple superposition of 2 different M′′(f) expressions having the form of the universal Bergman loss function, where it was found that the relaxation time is also thermally activated.

Reduced graphene oxide-polyethylene oxide composite films for humidity sensing via quartz crystal microbalance

A reduced graphene oxide (RGO)-Polyethylene Oxide (PEO) composite film was constructed on quartz crystal microbalance (QCM) with composite and bilayer film structures for ambient humidity detection. The morphology and chemical properties of the fabricated RGO-PEO composite materials were characterized by SEM, FTIR, Raman spectra and UV–vis spectroscopy respectively. The addition of RGO into PEO film contributes to a remarkable enhancement in dynamic response and sensitivity (20Hz/%RH) compared with the pure PEO film (10Hz/%RH). Furthermore, RGO-PEO composite film based sensor holds rapid response and recovery rates (11s and 7s at 84%RH @90% respectively), negative hysteresis (1.21%RH), stable repeatability and excellent long term stability. This research not only explore the feasibility of hygroscopic insulating polymer based composite in humidity detection but also provide an approach for advancement/optimization of QCM based humidity sensor.

PEO–CMC blend nanofibers fabrication by electrospinning for soft tissue engineering applications

Polyethylene oxide (PEO) and carboxymethyl cellulose (CMC)/PEO scaffolds are fabricated by electrospinning technique for soft tissue engineering applications. Morphological analysis of the scaffolds reveals formation of stable, regular and cylindrical fibers with 3-D porous interconnected network. Polyelectrolytic nature of CMC results in the formulation of thinner CMC/PEO fibers than pure PEO fibers. All the scaffolds are thermally stable and possess appreciable tensile properties to support cells and promote their growth. The non-toxicity and the ability of the scaffolds to facilitate cell proliferation are supported by MTT assay. This study contributes a promising approach to fabricate scaffolds for possible potential applications in soft tissue engineering applications.

Influence of Cobalt (II) Chloride Catalysed on the Thermal and Optical Characterization of PEO Based Solid Polymer Electrolytes

Solution-casting technique was employed for the preparation of solid polymer electrolyte based polyethylene oxide (PEO) with 0, 1, 3 and 5 weight percentage cobalt chloride (CoCl2) films were characterized by X-ray Diffractometry (XRD), Differrential Scanning Calorimetry (DSC), Scanning Electron Microscope (SEM) and Ultra Violet-Visible (UV-Vis.) Spectroscopy methods. The optical band gaps, absorption band edges and Urbach energy shows decrease with increasing of Co+2 ion concentration in the polymer matrix because of the formation of free radicals or cluster. The Thermogravimetry (TG) and Derivative Thermogravimetry (DTG) were used to examine the thermal stability of the film and it was found that the stability of the complexes is higher than that of the pure PEO due to the addition of CoCl2. The wavelength position of a fluorescence emission band varied by increasing of a dopant wt % of salt.

Bacterial filtration efficiency of green soy protein based nanofiber air filter.

High bacterial filtration efficiency (BFE) filters, based on nanofibers derived from blends of grain proteins and poly-ethylene-oxide (PEO), were produced by an electrospinning process. Specifically, polymer blends consisting of purified soy flour/PEO with a ratio of 7/3 were spun into nanofibers and characterized. A new laboratory based experimental apparatus for testing BFE was designed and used to test BFE of bacterial aerosols consisting of Escherichia coli (E. coli). Performances of soy protein based nanofiber filters with nanofiber mass varying from 1 to 5 g/m2 as well as a nanofiber filters prepared from pure PEO were compared. The results showed that BFE values for filters containing 5 g/m2 protein based nanofibers and PEO nanofiber filter were 100 and 81.5%, respectively. The results also indicated that the BFE increased as the protein content in the nanofiber filter increased. These novel protein based nanofiber filters have demonstrated a clear potential for effective removal and retention of E. coli bacteria during air-filtration. These filters can be effectively deployed in environments such as hospitals and senior residential areas to reduce bacterial infections.

How flow affects crystallization in a heterogeneous polyethylene oxide melt

Extension-induced crystallization in a heterogeneous polyethylene oxide (PEO) melt is investigated by small angle X-ray scattering (SAXS) and extensional rheology. The crystalline complex of PEO and sodium bromide is the heterogeneous component, which simulates the roles of crystal or strongly interacted additives during flow. It is aimed to demonstrate how the altered chain relaxation by the heterogeneous particle affects the crystallization. The main findings are listed as follows: (i) strain hardening occurs in heterogeneous melts but not in pure PEO. This indicates that the crystalline complex strengthens the entanglement network of free chains, leading to slower chain relaxation. (ii) In morphology, the orientation of lamellae becomes easier with the existence of the crystalline complex. A jump in the long period is also observed with large strain, accompanied by changes in the evolutional trend at the early stage. (iii) The crystallization kinetics converge with increasing strain; even the stress response significantly differs in different samples. Based on these findings, a quasi-network consisting of the crystalline complex and the entangled free chain is anticipated. Nucleation induced by the stretch of the quasi-network is supposed to lead to the change in crystallization observed.

Structure Formation of Ultrathin PEO Films at Solid Interfaces—Complex Pattern Formation by Dewetting and Crystallization.

The direct contact of ultrathin polymer films with a solid substrate may result in thin film rupture caused by dewetting. With crystallisable polymers such as polyethyleneoxide (PEO), molecular self-assembly into partial ordered lamella structures is studied as an additional source of pattern formation. Morphological features in ultrathin PEO films (thickness < 10 nm) result from an interplay between dewetting patterns and diffusion limited growth pattern of ordered lamella growing within the dewetting areas. Besides structure formation of hydrophilic PEO molecules, n-alkylterminated (hydrophobic) PEO oligomers are investigated with respect to self-organization in ultrathin films. Morphological features characteristic for pure PEO are not changed by the presence of the n-alkylgroups.

Phase Transitions in Polymers for Lithium Batteries

The Young’s modulus and the elastic energy dissipation of polyethylene oxide (PEO)-based lithium battery electrolyte membranes have been studied in this work. The membranes, formed by pure PEO and doped by LiCF3SO3, Li2S and ZrO2, were studied within a 90 K - 400 K temperature range. We observed the glass transition around 230 K and the first-order phase transformation from the crystalline to the amorphous phase around 330 K on heating. We also measured the isothermal kinetics of the transition from the amorphous to the crystalline state and found that it is slower in doped PEO. Moreover, we showed that for both samples the transformation becomes slower as the temperature increases between 319 and 331 K. The experimental results suggest that the amorphous state is stable at 331 K for a few hours before the transformation takes place. Finally, the moisture effects on the mechanical properties of pure and doped PEO membranes are reported.

Optical and electrical characterization of (PEO+methyl violet) polymer electrolytes

AbstractOptical properties and electrical conductivity of polyethylene oxide (PEO) with methyl violet dopant film have studied. The complexation of the methyl violet dopant with PEO was confirmed by X‐ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopic studies. The microstructure morphology have been analyzed by scanning electron microscope (SEM) for pure and dopant films. The UV‐absorption studies were made in the wavelength range 190–1100 nm for pure and doped films. The dc electrical conductivity data was collected using two probe technique in the temperature range 303–333 K. The UV–visible spectra showed the absorption band at 190 nm for pure PEO and doped from 208–224 nm region with different absorption intensities. The absorption edge, direct and indirect band gap were estimated using Mott and Davis Model. The optical activation energy can be determined using the Urbach rule, for pure PEO it was found 2.38 eV and 1.28–4.08 eV for doped films. The absorption band was shifted toward the higher frequency, the direct and indirect band gap decreases with increasing of dopant concentration, corresponds to the allowed inter band transition of electron. The dc electrical conductivity results shows that it increases with increasing dopant weight percentage and temperature which corresponds to the enhancement of charge mobility in these dye doped polymers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Embedded metal nanoparticles as localized heat sources: An alternative processing approach for complex polymeric materials

Metal nanoparticles were utilized as heating elements within nanofibers to demonstrate an alternative approach to thermally process nanostructured polymeric materials. In the photothermal process, resonant light excites the surface plasmon of the nanoparticle and the absorbed energy is converted into heat due to electron-phonon collisions. This heating is efficient and strongly localized, generated from the nanometer-sized metal particles embedded within the polymer. Composite polyethylene oxide (PEO) nanofibers, containing differing concentrations and types of nanoparticles, were fabricated by electrospinning and irradiated by a low intensity laser tuned specifically to the metal nanoparticle surface plasmon absorbance; aggregation of fibers, loss of fibrous structure, and ultimately, complete melting were observed. The photothermal response to irradiation increased with nanoparticle concentration as long as particle aggregation was avoided. Pure PEO nanofibers, or those containing metal nanoparticles possessing a non-resonant surface plasmon, were also irradiated but no melting occurred, demonstrating the controllable specificity of this approach.

Macromol. Biosci. 12/2010

Back Cover: Fibroblast cells adhere, spread, and grow on nanocomposite polymer films made from polyethylene oxide (PEO) that is cross-linked to silicate nanoparticles (Laponite clay). Although cells do not adhere to pure PEO, an increase in Laponite within the nanocomposite films offers sufficient adhesion sites for the cells to attach. Further details can be found in the full paper by P. J. Schexnailder, A. K. Gaharwar, R. L. Bartlett II, B. L. Seal, and G. Schmidt* on page 1416.

Preparation of manganese oxide–polyethylene oxide hybrid nanofibers through in situ electrospinning

AbstractManganese oxide nanoparticles–polyethylene oxide nanofibers as organic–inorganic hybrid were prepared via in situ electrospinning. Thus, electrospinning of polyethylene oxide solution with different manganese chloride concentration was carried out in gaseous ammonia atmosphere containing oxygen. The reaction of manganese chloride with ammonia produces manganese hydroxide, and then oxygen in the reaction media reacts with manganese hydroxide to yield manganese oxide. These two reactions occur during fiber formation. Transmission electron microscopy and scanning electron microscopy showed that manganese oxide (MnO2) nanoparticles were formed on the produced nanofibers of 100–600 nm in diameter. The existence of the formed MnO2 was also proved by X‐ray diffraction analysis, and it showed that the λ‐MnO2 nanoparticles were produced. Differential scanning calorimetry (DSC) analysis was used to determine the melting point and to calculate the crystallinity of the produced hybrid nanofibers. The DSC and thermogravimetric analysis results of the obtained nanofibers were compared with those of the nanofibers produced in electrospinning of pure polyethylene oxide solution. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010