Unusual enhancement in electrical conductivity of tin oxide thin films with zinc doping

Electrical conductivity of SnO(2)-based oxides is of great importance for their application as transparent conducting oxides (TCO) and gas sensors. In this paper, for the first time, an unusual enhancement in electrical conductivity was observed for SnO(2) films upon zinc doping. Films with Zn/(Zn + Sn) reaching 0.48 were grown by pulsed spray-evaporation chemical vapor deposition. X-Ray diffraction (XRD) shows that pure and zinc-doped SnO(2) films grow in the tetragonal rutile-type structure. Within the low doping concentration range, Zn leads to a significant decrease of the crystallite size and electrical resistivity. Increasing Zn doping concentration above Zn/(Zn + Sn) = 0.12 leads to an XRD-amorphous film with electrical resistivity below 0.015 ? cm at room temperature. Optical measurements show transparencies above 80% in the visible spectral range for all films, and doping was shown to be efficient for the band gap tuning.     

Patterns of the adsorption of bovine serum albumin on carboxymethyl dextran and carboxymethyl cellulose films

Patterns of the adsorption of bovine serum albumin on carboxymethyl dextran and carboxymethyl cellulose films are studied by means of microcontact printing, atomic force microscopy, and quartz crystal microbalance. It is shown that both the charge of polysaccharide macromolecules and the technique for deposition of their films onto the surface (via adsorption from a solution or covalent cross-linking) are factors that determine the degree of nonspecific adsorption of the protein on such films.     

Buildup mechanism of carboxymethyl cellulose and chitosan self-assembled films

Films with different numbers of layers have been built by alternating the adsorption of carboxymethyl cellulose (CMC) and chitosan (CHI) at different pH levels. The adsorption process was recorded by quartz crystal microbalance (QCM). The results showed that under all pH conditions considered, the growth of the films is nonlinear. The film construction performed at pH 4.0 (preferred assembly pH) with different numbers of bilayers (CMC/CHI as one bilayer) was also observed step by step by atomic force microscopy (AFM). Comparing the growth process from QCM with the surface morphological changes from AFM shows the existence of an inhomogeneous structure for the first nine bilayers, and, after a coalescence of islands, an increase in the number of bilayers was demonstrated. The possible growth mechanism was also evaluated.     

Ionic conductivity enhancement in the solid polymer electrolyte PEO9LiTf by nanosilica filler from rice husk ash

Rice husk ash is a cheap raw material available in abundance in rice-growing countries. It contains around 85–90 % amorphous silica. Rice husk ash, when subjected to a simple chemical precipitation method, will produce nanosilica which can be used for many industrial and technological applications. In this work, we have successfully synthesized nano-sized silica from local rice husk ash and prepared the nanocomposite solid polymer electrolyte, PEO₉LiTf:SiO₂. The resulting electrolyte has been characterized by X-ray diffraction, differential scanning calorimetry, atomic force microscopy, Fourier transform infrared spectroscopy, and complex impedance spectroscopy. The electrolyte shows about a 12-fold increase in ionic conductivity at room temperature due to the silica filler. In the nanocomposite electrolyte, nanosilica particles obtained from rice husk ash behaved very similarly to the commercial grade nanosilica and had a size distribution in the 25- to 40-nm range. As already suggested by us and by others, the O^2? and OH^? surface groups in the filler surface interact with the Li⁺ ions and provide hopping sites for migrating Li⁺ ions through transient H bonding, creating additional high-conducting pathways. This would contribute to a substantial conductivity enhancement through increased ionic mobility. An additional contribution to conductivity enhancement, particularly at temperatures below 60 °C, appears to come from the increased fraction of the amorphous phase, as evidenced from the reduced crystallite melting temperature and the reduced enthalpy of melting due to the presence of the filler.     

Mechanical enhancement of cellulose nanofibril (CNF) films through the addition of water-soluble polymers

Cellulose - In this work, water-soluble polymers were screened through solution casting and polyvinyl alcohol (PVA) and poly(2-ethyl-2-oxazoline) (PEOX) were found as reinforcement agents for...     

Ionic conductivity through thermoresponsive polymer gel: ordering matters

Thermoreversible polymer gel has been prepared using PEO-PPO-PEO block copolymer (Pluronic F77) which self-assembles into different microcrystalline phases like cubic, 2D-hexagonal, and lamellar. Addition of electrolyte (LiI/I(2)) converts the gel into a polymer gel electrolyte (PGE) which exhibits microphase-dependent ionic conductivity. The crystalline phases have been identified by SAXS as a function of the polymer concentration. It is found that the optimum value for the ionic conductivity (≈1 × 10(-3) S x cm(-1)) is achieved in the Im3m phase due to faster diffusion of ions through the 3D-interconnected micellar nanochannels. This fact is further supported by FTIR study, ionic transference number, and diffusion coefficient measurements.     

Structure and properties of biodegradable carboxymethyl cellulose films containing silver nanoparticles

Silver nanoparticles stabilized in a solution of sodium carboxymethyl cellulose with a degree of substitution of 0.85 and a degree of polymerization of 600 have been synthesized. The structuring; physical, chemical, and mechanical properties; and antimicrobial activities of films prepared from sodium carboxymethyl cellulose solutions containing silver nanoparticles have been studied. The shapes, quantities, and sizes of the silver nanoparticles occurring in the sodium carboxymethyl cellulose films were determined with the use of transmission electron microscopy, atomic force microscopy, and UV spectroscopy. It was found that an increase in the concentration of silver nitrate in sodium carboxymethyl cellulose solutions, as well as photoirradiation of the films, leads to the changes in the sizes and shapes of silver nanoparticles. The shapes, sizes, and quantities of silver nanoparticles determine their biological activity. An increase in the quantity of 5- to 25-nm silver nanoparticles was found to enhance the microbicidal activities of the carboxymethyl cellulose films.     

Characterization on conduction properties of carboxymethyl cellulose/kappa carrageenan blend-based polymer electrolyte system

The present work deals with the development of carboxymethyl cellulose (CMC) blended with kappa carrageenan (KC) as a host-based polymer electrolyte (PE) system. The CMC/KC films were successfully prepared using solution casting method and were characterized through electrical impedance spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD) methods, respectively. The FTIR spectrum revealed that the significant region of interaction transpires at wave number 1,057, 1,326, 1,584, and 3,387?cm^?1 which correspond to the bending of C–O–C, bending of –OH, asymmetric of –COO^? as well as the stretching of –OH, respectively. It has also been demonstrated that the complexation process occurred between CMC and KC. The CMC/KC blend PE system with a ratio of 80:20 achieved an optimum conductivity of 3.91?×?10^?7?S?cm^?1 and had the lowest crystallinity percentage as suggested by the XRD analysis.     

Boswellic acid captivated hydroxyapatite carboxymethyl cellulose composites for the enhancement of chondrocytes in cartilage repair

Recently tissue repairing bone grafted materials have been greater properties than the recapitulating intramembranous regeneration of natural bone especially cartilage damage regeneration. In this present work was designed and developed for the enhancement of chondrocyte generation for cartilage repair. Boswellic acid (BA) is a traditional compound used for the treatment of osteoarthritis. Boswellic acid subjected to involve the preparation of hydroxyapatite (HAP) and HAP-BA compounds were functionalized with carboxymethyl cellulose (CMC) to promote the extra-cellular matrix. HAP, HAP-BA and HAP-BA-CMC composites were characterized via their physicochemical properties through FTIR, XRD, SEM and TEM techniques. The antibacterial activity and chondrocyte cell variability were tested. At 14 days, HAP-BA-CMC composite was observed 67% of cell viability. The chondrocyte cell adhesion on the HAP-BA-CMC composite was investigated and it observed polygonal filopodia. From the results suggest that HAP-BA-CMC composite can improve the chondrocyte production for repair of damaged cartilage.     

Properties of carboxymethyl cellulose aqueous solutions with nanoparticle additives and the related composite films

The rheological properties of carboxymethyl cellulose aqueous solutions containing small amounts of purified montmorillonite and bentonite nanoparticles are studied. The viscosity of mixed solutions decreases after addition of 1 wt % nanoparticles. X-ray diffraction analysis shows that the films contain nanoparticles in the exfoliated state. An examination of the FTIR spectra of composite films suggests a shift in the absorption band due to Si-O groups. This phenomenon may be explained both by a change in the permittivity of the nanoparticle environment and by the formation of hydrogen bonds between Si-O groups and functional groups of cellulose ether. It is shown that the content of the added nanoparticles influences the mechanical characteristics of the films prepared from the systems of interest.     

Structural and electrical properties of polyvinyl alcohol (PVA):Methyl cellulose (MC) based solid polymer blend electrolytes inserted with sodium iodide (NaI) salt

This paper studies the structural and electrical properties of solid polymer blend electrolytes based on polyvinyl alcohol (PVA) and methylcellulose (MC) incorporated with sodium iodide (NaI). The polymer electrolyte films were assembled through a solution casting technique. The host matrix, which is doped with different NaI salt concentrations between 10 and 50 wt%, utilizes the most amorphous blend compositions (60 wt% Polyvinyl alcohol and 40 wt% methylcellulose). The structural behaviour of the electrolyte films was examined utilizing X-ray diffraction (XRD) and Fourier transformation infrared (FTIR) techniques. The semi crystalline nature of PVA:MC with inserted NaI was derived from the X-ray diffraction studies, while the XRD analysis suggests that the highest ion conductive sample displays the minimum crystalline nature. The interaction between polymer blends and inserted salt was conceived from the FTIR investigation. Shifting of peaks and variation in the intensity of FTIR bands was detected. To investigate the structural properties and calculate the degree of crystallinity of the films, the (XRD) technique was employed, while electrical impedance spectroscopy (EIS) was utilized for studying the conductivity of the samples. In order to comprehend all of the electrical properties of the ion-conducting systems, the EIS outcome of each electrolyte was matched with Equivalent Electrical Circuits (EEC) s. Ion transport parameters including mobility, carrier density and diffusion are well assessed for the samples and the dielectric properties were compared with the conductivity measurement. At lower frequencies, the dielectric constant was elevated and dielectric loss was detected. Loss tangent and electric modulus plots were used to study the relaxation nature of the samples. The highest ambient temperature conductivity of PVA loaded 50 wt% of NaI was determined to be 1.53 × 10⁻⁵ S/cm. The loss tangent relaxation peak shifts towards high-frequency side which indicates the decrease of relaxation time and faster ion dynamics.     

Effect of carboxymethyl cellulose concentration on physical properties of biodegradable cassava starch-based films

Background  

Cassava starch, the economically important agricultural commodity in Thailand, can readily be cast into films. However, the cassava starch film is brittle and weak, leading to inadequate mechanical properties. The properties of starch film can be improved by adding plasticizers and blending with the other biopolymers.     

Compatibility of carboxymethyl cellulose ionized to various degrees with poly-N-vinylformamide in composite films

Composite films were obtained from aqueous solutions of blends of carboxymethyl cellulose ionized to various degrees and poly-N-vinylformamide. The composition ranges in which the polymers are compatible were determined by solvent vapor sorption and by dynamic mechanical analysis. The heat resistance of the films and the interaction of the polymers in the solid state were examined by DSC, TGA, and Fourier IR spectroscopy.     

Electrochemical and electrocatalytic properties of myoglobin and hemoglobin incorporated in carboxymethyl cellulose films

Protein-CMC films were made by casting a solution of myoglobin (Mb) or hemoglobin (Hb) and carboxymethyl cellulose (CMC) on pyrolytic graphite electrodes. In pH 7.0 buffers, Mb and Hb incorporated in CMC films gave a pair of well-defined and quasi-reversible cyclic voltammetric peaks at about -0.34 V vs. SCE, respectively, characteristic of heme Fe(III)/Fe(II) redox couples of the proteins. The electrochemical parameters such as apparent standard heterogeneous electron transfer rate constants (k(s)) and formal potentials (E degrees ') were estimated by square wave voltammetry with nonlinear regression analysis. In aqueous solution, stable CMC films absorbed large amounts of water and formed hydrogel. Scanning electron microscopy of the films showed that interaction between Mb or Hb and CMC would make the morphology of dry protein-CMC films different from the CMC films alone. Positions of Soret absorbance band suggest that Mb and Hb in CMC films retain their secondary structure similar to the native states in the medium pH range. Trichloroacetic acid, nitrite, oxygen, and hydrogen peroxide were catalytically reduced at protein-CMC film electrodes.     

Control of bending electrostriction in polyurethane films by doping with salt

We systematically investigated the effect of doping with salt on the bending electrostriction in polyurethane films. When a film was doped with sodium acetate, it was bent toward the cathode side by the application of an electric field. However, when a film was doped with zinc bromide, it was bent toward the anode side. Thus, we found a way of controlling the bending direction. We also investigated the mechanism of the effect of the doping. Doping is believed to be a treatment that can control the bending deformation through modification of the charge injection, the major origin of the deformation. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 1061–1069, 2001     

Ionic limiting molar conductivity calculation of Li-ion battery electrolyte based on mode coupling theory

A method is proposed based on mode coupling theory in which the ion transference number is introduced into the theory. The ionic limiting molar conductivities of LiPF6, LiClO4, LiBF4, LiCF3SO3, Li(CF3SO3)2N, LiC4F9SO3, and LiAsF6 in PC(propylene carbonate), GBL(gamma-butyrolactone), PC(propylene carbonate)/EMC(ethylmethyl carbonate), and PC(propylene carbonate)/DME(dimethoxyethane) are calculated based on this method, which does not involve any adjustable parameter. The results fit well to the literature data which are calculated by an empirically adjusted formula. This presents a potential way to calculate the conductivities of Li-ion battery electrolytes.     

Ionic conductivity of poly(2-vinyl pyridinium) salt in solid state

The preparation, characterization and conductivities of poly(2vinylpyridine), P-2VP and its fluoride derivative are reported here. The polymer P-2VP was prepared by thermal polymerization of 2vinylpyridine, 2VP and its salt, by acidification with HF. The formation of P-2VP salt was confirmed by IR and ¹H NMR techniques. Conductivities were determined from 30 to 110 °C in solid state. The addition of F⁻ ion increases the ionic conductivity of the polymer dramatically. The P-2VP-HF behaves as an intrinsic conducting polymer. The determination of the molecular mass of P-2VP and P-2VP-HF indicated that 95% of pyridine molecule was hydrofluorinated.     

Electrokinetic studies of cotton Part III. The surface conductivity at the cellulose/electrolyte interface

Summary The contribution of surface conductivity to the conductivity of the cotton plug at different concentrations of electrolytes is calculated. The experimental values for surface conductivities are several orders of magnitude higher than the theoretical values calculated from the diffused part of the double layer. The discrepancy between the experimental and theoretical data is explained on the basis of the concept based on the structure of water.

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Zusammenfassung Der Beitrag der Oberflächenleitfähigkeit zur Leitfähigkeit eines Baumwollepfropfens bei verschiedenen Elektrolytkonzentrationen wurde berechnet. Es wurde festgestellt, daß die experimentellen Werte der Oberflächenkonduktivität um mehrere Größenordnungen höher sind im Verhältnis zu den auf der Basis der Diffusionsdoppelschichten tehoretisch errechneten Werte. Die zwischen den beobachteten Werten und den Versuchswerten bestehende Diskrepanz wurde anhand der Wasserstruktur geklärt.

     

Molecular dynamics simulations of the characteristics of sodium carboxymethyl cellulose with different degrees of substitution in a salt solution

Sodium carboxymethyl cellulose (SCMC) with different degrees of substitution (DS) possesses structural characteristics and physicochemical properties that are important in broad areas of industrial applications. This reported work investigated the structural characteristics, including the effective length (L _ef), the radius of gyration (R _g), and the hydrodynamic radius (R _H), and the physicochemical properties, including intrinsic viscosity ([η]) and salt tolerance, of SCMC with a DS more than 1.0 in NaCl solution using molecular dynamics (MD) simulations. In the MD simulations, the DS of SCMC varied from 1.2 to 2.8, and the NaCl concentration varied from 0 to 1.4 mol/L. MD simulation results showed that with the increment of NaCl concentration, the L _ef (or R _g or R _H) of SCMC decreased; with the increment of the DS, the L _ef of SCMC increased. Also, the variation tendency of [η] in the NaCl solution was consistent with its L _ef (or R _g or R _H). It was noted that the salt tolerance (represented by D) of SCMC increased as the DS increased. In addition, the sharp variation of the D value of SCMC occurred in the range of DS of 1.6 to 2.0, which agreed with the reported experimental results. Radial distribution function analyses showed that the Na⁺ cations had a stronger interaction with the carboxyl groups in SCMC with lower DS when it was present in a salt solution of higher concentration, which also reasonably explained the variation of L _ef, R _g, R _H, [η], and D of SCMC in NaCl solution.