Search results for "CONDUCTIVITY"

Different approaches in sulfonated poly (ether ether ketone) conductivity measurements

2019

Ion conductivity of sulfonated poly (ether ether ketone) (SPEEK) membranes with various degree of sulfonation (DS) was investigated using impedance analysis with different measuring cell configuration and ion conductivity was calculated from resistances of polymer membranes. SPEEK was synthesized from poly (ether ether ketone) (PEEK) via sulfonation reaction in concentrated sulfuric acid (95-98%). Scanning electron microscopy (SEM) analysis of membrane surface was performed to determine possible mechanical damage to the membrane during resistance measurements.

Photoconductivity of Poly(Arylenevinylene)S and Poly(Hetarylenevinylene)S

1994

Abstract The intramolecular condensation of aromatic Schiff bases leads under strong alkaline conditions to the poly(arylenevinylene)s and poly(hetarylenevi-nylene)s A - H. Due to the extreme stereoselectivity the resulting products are rigid, (E)-configurated polymers. The broad band gap of the unsubstituted intrinsic insulators is decreased by alkoxy substituents. Investigations of the photoconductivity and the photoreactivity, as well as of the AC-conductivity of some undoped, doped and quaternized systems are performed.

Proton Conducting Membrane Prepared by Cross-Linking Highly Sulfonated Peek for PEMFC Application

2009

The proton conducting membrane was prepared by cross-linking highly sulfonated and sulfinated poly(etheretherketone) (SsPEEK). The cross-linked membrane is low cost due to its use of non-expensive chemical and simple production procedure. The membrane exhibited high proton conductivity (0.04 S/cm at 60 °C), extremely reduced water uptake, enhanced strength and stability compared with that of non-cross-linked membrane. These results suggested that the cross-linked PEEK membrane is a suitable candidate of proton conducting membranes for polymer electrolyte membrane fuel cell (PEMFC) applications, particularly promising to be used in direct methanol fuel cell (DMFC) due to its lower methanol c…

Theoretical Design of Organic Metals Based on the Phthalocyanine Macrocycle

1990

Phthalocyanine molecular crystals and cofacially linked polymers are well documented as low-dimensional materials that may attain high electrical conductivities. Air-stable conductivities on the order of 1 to 1000 S/cm after partial oxidation by iodine have been reported.1–3 These conductivity studies indicate that the electrical conductivity has very little dependence on the identity of the atom complexed in the cavity, but is strongly dependent on the orientation and spacing of the phthalocyanine rings. A columnar stacking with minimum spacing leads to a maximum interaction between π-molecular orbitals on adjacent rings and promotes the highest conductivity. More effective π-interactions …

Optical Field-Induced Mass Transport in Soft Materials

2013

Abstract The dependence of the surface relief formation in amorphous chalcogenide (As 2 S 3 and As-S-Se) and Disperse Red 1 dye grafted polyurethane polymer films on the polarization state of holographic recording light beams was studied. It is shown that the direction of lateral mass transport on the film surface is determined by the direction of light electric vector and photoinduced anisotropy in the film. We propose a photoinduced dielectropfhoretic model to explain the photoinduced mass transport in amorphous films. Model is based on the photoinduced softening of the matrix, formation of defects with enhanced or decreased polarizability, and their drift under the electrical field gradi…

Effect of conductivity of hole injection layer on the performance of a blue light emitting solution processable OLED

2005

The performance of blue emitting OLED devices, using a polyspiro as blue light emitting polymer, were studied as a function of the conductivity of a novel hybrid hole injection material. The hole injection material is based on a polyarylamine using a molecular magnet as oxidant. The charge density and the luminance of the devices changed considerably with increasing conductivity of the hole injection layer. The change in device performance can be attributed to a change from a hole limited device to a balanced charge carrier device and eventually to an electron limited device. The performance of the optimized device configuration is significantly improved with respect to a device making use …

Investigation on lithium/polymer electrolyte interface for high performance lithium rechargeable batteries

1997

Abstract Performance data of several linear and cross-linked polymer electrolytes are reported and the electrochemical criteria for the selection of electrolytes to be used in electric vehicle lithium metal batteries are discussed. Further, laboratory lithium cells with LiMn2O4 composite cathode were tested to ascertain the effective viability of these polymer in solid-state batteries and preliminary results are reported. This study clearly demonstrates the importance of a broad-based electrochemical characterization in selecting an electrolyte for lithium metal batteries.

Metallic Conductivity Down to 2 K in a Polyoxometalate-Containing Radical Salt of BEDO-TTF

2004

Fabrication of soft-etched nanoporous polyimide membranes for ionic conduction and discrimination

2021

Abstract Ionic selectivity in nanopores is usually based either on steric or charge exclusion mechanisms. By simultaneously incorporating both mechanisms into a functionalized membrane, an improved control over selectivity can be achieved. We describe the fabrication and experimental characterization of alkali metal cation-selective nanopores in heavy ion-tracked polyimide (PI) membranes using the soft-etching (SE) technique. The latent ion tracks in the PI membrane are selectively dissolved by an organic solvent to form tiny pores without affecting the bulk material. The ionic transport properties of SE-PI membranes are characterized using different electrolyte solutions containing alkali …

Universal Transients in Polymer and Ionic Transition Metal Complex Light-Emitting Electrochemical Cells

2012

Two types of light-emitting electrochemical cells (LECs) are commonly distinguished, the polymer-based LEC (p-LEC) and the ionic transition metal complex-based LEC (iTMC-LEC). Apart from marked differences in the active layer constituents, these LEC types typically show operational time scales that can differ by many orders of magnitude at room temperature. Here, we demonstrate that despite these differences p-LECs and iTMC-LECs show current, light output, and efficacy transients that follow a universal shape. Moreover, we conclude that the turn-on time of both LEC types is dominated by the ion conductivity because the turn-on time exhibits the same activation energy as the ion conductivity…