Conductivity enhancing agents

PPy doped with protonic acid shows a higher electrical conductivity compared to that doped with organic sulfonic acid (Lee et al., 2014), and a PPy film with electrical conductivity up to 2000 S cm 1 was prepared (Qi et al., 2012). For PEDOTrPSS, many secondary dopants, commonly called conductivity enhancement agents, such as, polyols, alcohols, surfactants, salts, acids, and organic solvents, have been widely used to enhance the electrical conductivity (McCarthy et al., 2014). It reached 2084 S cm with the use of a nonvolatile ionic liquid (Badre et al., 2012) and 3065 S cm or even higher after H2SO4 treatment at high temperature (Xia et al., 2012). 

Additional additives which may optionally be present in an inkjet ink composition include thickeners, conductivity enhancing agents, anticoagulants, drying agents, and defoamers (20). 

One of the reasons why poly(3,4-ethylenedioxythiophene) (FEDOT) has become a successful conductive polymer is the availability as a polymer dispersion. In combination with poly(styrenesulfonic acid) (PSS) as a counterion, a polyelectrolyte complex (PEC) can be prepared that forms a stable dispersion, which is producible on an industrial scale and can be used in many deposition techniques. To understand the function of PSS and the requirements for the formation of a stable PEC, this chapter will start with a general view on polyelectrolyte complexes. This is followed by a section on the synthesis and properties of PEDOT PSS dispersions, the properties of PEDOTPSS films, and the function of conductivity enhancement agents. 

PEDOT PSS Ratio Layer Thickness pH Conductivity Enhancing Agent c ( RT)/ (S/cm) To/K a Reference... 

PEDOTrPSS grades used and experimental conditions employed as summarized in Table 9.2. It is obvious that all comparative data acquired indicate that the DC conductivity of pristine material is by two to three orders of magnitude lower compared to films treated with conductivity enhancing agents as discussed in detail in Section 9.3. 

Occasionally, the term secondary dopant is used more loosely for a second redox treatment of a polymer chain that has already been subjected to a redox agent. Generally, the term is used, however, in the way as defined by MacDiarmid and Epstein and will therefore only be used in this more specific sense in this book. Also, the term conductivity enhancement agent is widely used as an alternative for the term secondary doping. 

It should be noted that the pristine PEDOTrPSS dispersions quoted in the different references are not identical so that the reported enhancement factors give only a crude orientation rather than an exact measure of the quality of such an additive as a conductivity enhancement agent. The highest conductivities are currently obtained using dimethyl sulfoxide as an additive. ... 

Although the concentration of these additives is low in the initial mixture, their concentration increases in the film-forming process due to their low vapor pressure, as compared to the main solvent water. A minimum quantity is required for the initial mixture to achieve the effecD In the final film the presence of the conductivity enhancement agent is no longer necessary. Based on these findings it becomes clear that the film forming process is the critical step for the secondary dopants to come into effect. Changes are observed both for the surface and the bulk of the material. On the surface of a pristine PEDOTPSS sample PSS is foimd in excess. When a secondary dopant is used, the surface composition resembles the bulk composihon.i ... 

In 1988, Terry and coworkers attempted to homopolymerize ethylene, 1-octene, and 1-decene in supercritical C02 [87], The purpose of their work was to increase the viscosity of supercritical C02 for enhanced oil recovery applications. They utilized the free radical initiators benzoyl peroxide and fert-butyl-peroctoate and conducted polymerization for 24-48 h at 100-130 bar and 71 °C. In these experiments, the resulting polymers were not well studied, but solubility studies on the products confirmed that they were relatively insoluble in the continuous phase and thus were not effective as viscosity enhancing agents. In addition, a-olefins are known not to yield high polymer using free radical methods due to extensive chain transfer to monomer. 

One of the big drawbacks associated with the use of many conducting polymers as electrochromic materials is their low cycle life stability. To overcome this, and other electrochromic properties, many composite materials have been studied. These composites include mixtures with other optically complementary, conducting polymers and inorganic electrochromes, such as tungsten trioxide and Prussian Blue, and colour enhancing agents or redox indicators, exemplified by the inherently electrochromic indigo carmine (1.96). °... 

A study on the feasibility of the enhanced EK-Fenton process for the remediation of hexachlorobenzene (HCB) in a low-permeability soil was conducted by Oonnittan, Shrestha, and Sillanpaa (2008). In that work, kaolin was spiked with HCB and treated by the EK and EK-Fenton processes. )3-cyclodextrin was used to enhance the solubility of HCB in pore fluid. Two EK experiments were conducted to observe the suitability of j8-cyclodextrin as a flushing solution for these processes. Another test conducted was the EK-Fenton test using )3-cyclodextrin as an enhancing agent. Results showed that the type of flushing solution, system pH, electric current, and EO flow are of significance for HCB removal. 

Mlcrofiltra.tlon, Various membrane filters have been used to remove viral agents from fluids. In some cases, membranes which have pores larger than the viral particle can be used if the filtration is conducted under conditions which allow for the adsorption of the viral particle to the membrane matrix. These are typically single-pass systems having pore sizes of 0.10—0.22 lm. Under situations which allow optimum adsorption, between 10—10 particles of poHovims (28—30 nm) were removed (34—36). The formation of a cake layer enhanced removal (35). The titer reduction when using 0.10—0.22 p.m membrane filters declined under conditions which minimized adsorption. By removal standards, these filters remove vimses at a rate on the low end of the desired titer reduction and the removal efficiency varies with differences in fluid chemistry and surface chemistry of viral agents (26). 

Due to the strong ionic nature of lithium trifluoromethanesulfonate, it can increase the conductivity of coating formulations, and thereby enhance the dissipation of static electricity in nonconducting substrates (see Antistatic agents) (25). 

The performance of soluble oils is made possible not only by their high specific heat and thermal conductivity but by their low viscosity, which permits good penetration into the very fine clearances around the cutting zone. Consequently, these fluids are used mainly where cooling is the primary requirement. Lubricating properties can be improved by polar additives, which are agents that enhance the oiliness or anti-friction characteristics. Further improvements can be effected by EP (extreme-pressure) additives, which are usually compounds of sulfur or chlorine. 

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