Switching properties

The fact that these unique polymer materials conduct electricity is fascinating enough, but the ability to switch their properties in situ using simple electrical stimuli is intriguing. Of course, this ability is dependent on possessing conductivity initially. 

Charge can be reversibly added to or removed from a conducting polymer by cycling the material through oxidized and reduced states. As the switch from oxidized to reduced state occurs, there is a concomitant decrease in the conductivity. 

Effect of the Counterion on the Tensile Strength and Conductivity of Polypyrrole (PPy) Films 

Effect of Adding Dodecyl Sulfate (DS) to Polypyrrole/(PPy) Para-Toluene Sulfonate (pTS) Films 

Note All films were prepared using the same electrochemical conditions. Polymerization current density = 2 mA/cm2 polymerization time = 10 min amount of charge passed = 1.2 C/cm2. 

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The cationic nature of SCO complexes makes them good candidates to investigate the coexistence of conductive and switching properties within a single material. 

Ma G, Muller AM, Bardeen CJ, Cheng Q (2006) Self-assembly combined with photopolymerization for the fabrication of fluorescence tum-on vesicle sensors with reversible on-off switching properties. Adv Mater 18 55-60... 

Ultrafast optical switching properties of single-wall carbon nanotube polymer composites at 1.55 pm. Appl. Phys. Lett. 81 975-977. 

In Ref. [75], it is discussed in more detail why it is advantageous to convolute the response of the temperature grating into the excitation and how to treat systematic errors arising from this approximation and from imperfections of the components in the setup. Especially the switching properties of the Pockels cell require careful analysis, since the switching number increases from 2 in case of pulsed excitation to approximately N in case of pseudostochastic binary sequences. 

This led to the idea that see-saw-like switching states between region 1 and 3 may be quantized as the stationary state of P- and M-superposition, but not due to the transition between 100% pure P- and 100% pure M-states. These switching properties may be interpreted as the consequence of the superpo-... 

Photochromic trans- d.v-isomerization and molecular switching properties of azo-conjugated metal complexes with heterocycles as ligands 04BCJ407. 

Special considerations filling with carbon black can lead to the development of material with switching properties (10 fold increase in resistance at certain tempera-ture) crystallization history has effect on performance of switching material ... 

N. Stevens, Nonlinear Optical Switching Properties of Dye-doped Inorganic/Organic Composite Films, Ph.D. thesis. The Graduate Center, New York, pp. 28-29 (2006). 

One expectation has focused on the unique structure of DNA and hypersensitive conductivity dependence on the base composition as fundamental wires in ultra-small scale electronic circuits,Combination of the DNA-structure with attached redox or other functional groups would add other electronic features resembling amplification, rectification, and switch properties such as observed recently. Such expectations are, however, fraught with prodigious challenges relating to the physical discrepancy between the aqueous biological media for natural DNA-function and the completely different environment required for DNA-function in putative electronic devices. 

Figure 3.4.21 Channel switching property by changing from a bent 1 D chain skeleton to a...

The following discussion is concerned with the influence of various contacts to Cu(TCNQ) and different device structures on the switching properties. As the switching process is activated electrically, an influence of the contact is... 

These results for contacts, which do not have an interfacial oxide layer, but do show switching properties, indicate that the oxide layer may assist the switching process, but can not be the main reason for the phenomenon. This is supported by other reports on switching in configurations without oxide interlayers [12, 13]. Remarkably, these reports also relate to structures with very small cross sections, i.e. an STM-tip and nanowires. Therefore, the oxide layer seems to be essential to achieve stable switching in devices with relatively large-area contacts. 

The size of the electrode also affects switching properties. The ability to switch at high scan rates has been demonstrated previously by other workers, using microelectrodes.47 Conversely, larger electrodes will be slower to switch, and the degree (percentage of material affected) of switching will be much less efficient. 

The related fully sulfonated, self-doped polymer poly(2-methoxyaniline-5-sulfonic acid) (PMAS 9) may be prepared under normal atmospheric pressure by the oxidation of 2-methoxyaniline-5-sulfonic acid (MAS) monomer with aqueous (NH4)2S208 in the presence of ammonia or pyridine (to permit dissolution of the MAS monomer).141 The polymerization pH was therefore >3.5. Subsequent studies showed that the product consisted of two fractions a major fraction with Mw of ca. 10,000 Da whose electrical conductivity and spectroscopic and redox switching properties were consistent with a PAn emeraldine salt, as well as a nonconducting, electroinactive oligomer (Mw ca. 2,000 Da).143 144 Pure samples of each of these materials can be obtained using cross-flow dialysis.145... 

Polythiophenes are normally produced from nonaqueous media because the monomer is more soluble in these. Also, a wider electrochemical potential window is available, and this is required as polythiophene is more difficult to oxidize than pyrrole. The influence of water on the polymerization process for thiophene and on the redox switching properties has been studied.1314 The presence of water as low as... 

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