Electrochemically controlled drug delivery based on intrinsically conducting polymers.

In situ spectroscopic investigations of electrochromism and ion transport in a poly (3,4-ethylenedioxythiophene) electrode in a solid state electrochemical cell

Poly mono-, bi- and trithiophene: effect of oligomer chain length on the polymer properties

Different oxidation levels, regarded as polaron, bipolaron, and metallic states, are usually found in conjugated heterocyclic polymers. We found that poly(3,4-ethylenedioxythiophene) (PEDOT) also has these different oxidation levels, using in situ UV−VIS−NIR spectroscopy. The transitions between the different oxidation levels were, however, never clearly observed in cyclic voltammetry (CV). Instead it usually shows a broad oxidation peak and two reduction peaks. The CV of PEDOT at macroelectrodes shows a pair of redox peaks separated by 0.9 V at low scan rates, indicating two irreversible electron transfer steps. Using an ultramicroelectrode, we found these two pairs of redox peaks in PEDOT, as well as for poly(3-methylthiophene) (PMeT). These two peaks cannot be explained by the existence of two forms of the materials, whether due to two different conjugation lengths, crystalline or noncrystalline phases, or created by conformational changes. We deduced that there should be a third redox peak. With fast ...

Three-Step Redox in Polythiophenes: Evidence from Electrochemistry at an Ultramicroelectrode

A mixed ionic–electronic conductor (MIEC) of polypyrrole (PPy) synthesized with poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAAMPSA), which is water-dispersible and is in the form of nanoparticles intertwined by the PAAMPSA, is explored as an additive in sulfur cathodes for rechargeable lithium–sulfur (Li–S) batteries. A S-MIEC composite containing a sulfur content of 75 wt % was synthesized by an in situ deposition of sulfur with MIEC. The sulfur retains an orthorhombic phase randomly mixed with MIEC nanoparticles, exhibiting a lower thermal decomposition temperature than the pristine sulfur. Cathodes containing the S-MIEC composite were prepared and evaluated in half cells by cyclic voltammetry and galvanostatic cycling. The S-MIEC composite cathode shows excellent electrochemical stability as the MIEC facilitates ion and electron transfer and capture intermediate polysulfides within the electrodes. The MIEC in the composite electrodes forms a porous, 3D heterostructure providing good electroche...

Enhanced Cyclability of Lithium–Sulfur Batteries by a Polymer Acid-Doped Polypyrrole Mixed Ionic–Electronic Conductor

IR and Raman studies of polythiophene prepared by electrochemical polymerization

On the nature of redox processes in the cyclic voltammetry of polypyrrole nitrate in aqueous solutions

On the metallic temperature dependence of the conductivity of doped polyacetylene

It has been observed that the band texture of thermotropic liquid crystalline polymers (LCPs) is formed at the shearing temperature during the relaxation of shear. The band spacing increases with increasing shearing temperature between T m and T i, but is independent of shearing rate within the range of our experiments. The angle of zigzag orientation of the molecular chain fibrils with respect to the direction of shear is independent of the shearing temperature. The relaxation rate of the shear-induced band texture depends on the width of the bands formed. The wider the band spacing is, the slower the relaxation. When specimens with shear-induced bands of different spacings are annealed at a certain temperature for 10 min, they are all converted to a new band texture of the same spacing of around 1 μm. These bands with a small spacing generated during cooling are termed the solidification-induced band texture. When the specimen with shear-induced bands is annealed for a short time, so that the b...

Solidification-induced and shear-induced band texture in thermotropic liquid crystalline polymer films

The drift mobilities of carriers in amorphous charge-transfer complexes of PVCz-TNF were obtained by Time-of-Flight. Differences in the transport characteristics between electrons and holes were observed. The transient current trace of electrons has a knee by which the transit time can be determined, but. the current trace of holes is featureless indicating that tT is dispersive. The transient current of holes can be analysed by Scher-Montroll theory. At low electrical field μh is independent of the field. Combining the results of dark conductivity measurements, we conclude that the non-ohmic conductivity at high field is contributed by the field-dependent mobilities and carrier concentrations that are both increasing with the field strength.

Qian Renyuan

Papers

IR and Raman studies of polythiophene prepared by electrochemical polymerization

On the nature of redox processes in the cyclic voltammetry of polypyrrole nitrate in aqueous solutions

On the metallic temperature dependence of the conductivity of doped polyacetylene

Solidification-induced and shear-induced band texture in thermotropic liquid crystalline polymer films

DRIFT MOBILITIES OF CARRIERS IN AMORPHOUS FILMS OF PVCz-TNF CHARGE-TRANSFER COMPLEXES