β,β-Disubstituted oligothiophenes, a new oligomeric approach towards the synthesis of conducting polymers

Smie, Andreas; Synowczyk, A.; Heınze, Jürgen; Alle, R; Tschuncky, Peter; Götz, Günther; Bäuerle, Peter

doi:10.1016/s0022-0728(98)00100-4

Cited by 98 publications

(79 citation statements)

References 46 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…[38] The CVs of the films are consistent with the data obtained in solution. Figure 2 a shows a single oxidation wave with a maximum at 0.66 V and two reduction waves at 0.48 V and 0.37 V in the first cycle and two reversible oxidation waves at 0.47 V and 0.56 V in the second doping cycle.…”

supporting

confidence: 84%

Electrochemically Induced Formation of Independent Conductivity Regimes in Polymeric Tetraphenylbenzidine Systems

2010

View full text Add to dashboard Cite

[a] p-Conjugated organic polymers have gained increasing interest since their discovery because of their ability to become electrically conducting upon doping.[1] The understanding of the mechanism of conductivity in these materials is highly important both from a fundamental point of view [2] and for their applications in devices. [3][4][5] Conjugated polymers are nonconducting in the neutral state and conducting in the charged state. Electrochemical studies coupled with conductance measurements of conjugated polymers typically show conductivities over large potential ranges. [6,7] In the literature several models exist to describe the conductivity mechanism in conjugated polymers. [8][9][10][11] Probably the most established in the electrochemical literature is the bipolaron model, which is derived from solid-state materials and based on the band model. [9,12,13] Different aspects of this model are discussed in the literature. Upon increasing the oxidation level, first polarons (radical cations) and then bipolarons (dications) are formed. The bipolaron model explains conductivity in conjugated polymers with the transport of first locally stabilized polarons followed by transport of bipolarons. According to theoretical predictions, the broadening of the bipolaron states produces new unfilled valence bands and leads to metal-like conduction at high doping levels. A characteristic sigmoidal shape of conductivity as function of charging and the disappearance of the ESR signal at high charging support this view involving the transport of spinless bipolaronic charge carriers and not of electrons.[14] However, some experiments reveal a decrease of the conductivity after reaching the plateau at high doping levels, [6,[15][16][17] which cannot be unambiguously explained by a simple bipolaron conduction in conjugated polymers. Different explanations have been presented in the literature, for example, mixed valence exchange processes between polaron and neutral or polaron and bipolaron sites. [16,18] Wrighton reports that at high charging levels the decrease in conductivity can be attributed to localization of charges on the chains.[6] Very recently, Heinze et al. studied 3D hybrid networks consisting of dendritic cores of polyphenylene systems and hexathiophene oligomers crosslinking the dendritic cores.[19] Surprisingly, cyclic voltammetry coupled with in situ conductance measurements showed two independent regimes of conductivity which can be attributed to the hexathiophene oligomers and polyphenylene cores, respectively. A first analysis of this phenomenon supports the view that the conductivity of this material-especially of the hexathiophene segments-results from hopping processes [20][21][22] within mixed valence states. Hexathiophenes are interpreted as the oligomeric analoga of polythiophenes. Fichou and Garnier reported formation of polarons and bipolarons upon increased doping level by spectroscopic evidence.[23] However, no experimental data on the conductivity were shown that might have confirmed the bipo...

show abstract

supporting

confidence: 84%

Electrochemically Induced Formation of Independent Conductivity Regimes in Polymeric Tetraphenylbenzidine Systems

2010

View full text Add to dashboard Cite

show abstract

“…This finding excludes the formation of a network. In situ conductivity measurements on films of these materials carried out simultaneously with voltammetric measurements in an electrochemical cell [26] show that during charging the conductivity drastically increases reaching a maximum value of 8. 3 10 À2 S cm À1 at a potential of + 1.5 V (Figure 3 b).…”

Section: Methodsmentioning

confidence: 99%

3D‐Hybrid Networks with Controllable Electrical Conductivity from the Electrochemical Deposition of Terthiophene‐Functionalized Polyphenylene Dendrimers

et al. 2005

View full text Add to dashboard Cite

Unusual conductivity effects: Suitably functionalized dendrimers (see picture) are capable of forming truly covalent three‐dimensional networks with remarkably high conductivity on electrochemical doping. Depending on the charging level of the electroactive components used as building blocks for the dendrimer core and the perimeter, two separated regimes of electrical conductivity can be observed.

show abstract

“…The working electrode was Pt-sealed in a soft glass (microarray working electrode, 5-m gap) coated by the polymer blend. The working electrode was separated from the potentiostat by two 1-k⍀ resistors 24 ( Fig. 2).…”

Section: Blend Characterizationmentioning

confidence: 99%

Electroactive mixtures of polyaniline and EPDM rubber: Chemical, thermal, and morphological characterization

Domenech

Bortoluzzi

Soldi

et al. 2002

J of Applied Polymer Sci

View full text Add to dashboard Cite

ABSTRACT:A new route for blending polyaniline (PAni) and EPDM rubber was devised with maleic anhydride as a compatibilizer precursor. Rubber matrices containing ammonium peroxidisulfate and dodecyl benzene sulfonic acid were cast from organic solvents. Exposure to the monomer vapors allowed the chemical polymerization of aniline. The influence of PAni and the compatibilizer on the thermal properties, chemical structure, electrical conductivity, and morphology of the mixtures was observed with differential scanning calorimetry, thermogravimetric analysis, Fourier transform infrared, in situ conductivity measurements, and optical microscopy. The micrographs showed a good distribution of the PAni complex in the matrix. The use of approximately 2 wt % compatibilizer resulted in chemical interactions between maleic anhydride and the PAni complex formed with dodecyl benzene sulfonic acid, which could enhance the compatibility between the polymers. The obtained blends reached relative electrical conductivity values of up to 9 ϫ 10 Ϫ3 S cm Ϫ1 .

show abstract

β,β-Disubstituted oligothiophenes, a new oligomeric approach towards the synthesis of conducting polymers

Cited by 98 publications

References 46 publications

Electrochemically Induced Formation of Independent Conductivity Regimes in Polymeric Tetraphenylbenzidine Systems

Electrochemically Induced Formation of Independent Conductivity Regimes in Polymeric Tetraphenylbenzidine Systems

3D‐Hybrid Networks with Controllable Electrical Conductivity from the Electrochemical Deposition of Terthiophene‐Functionalized Polyphenylene Dendrimers

Electroactive mixtures of polyaniline and EPDM rubber: Chemical, thermal, and morphological characterization

Contact Info

Product

Resources

About