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Dispersion as the Key to Processing Conductive Polymers
Abstract
A review is given describing experimental and theoretical aspects of heterogeneous polymer systems (as example: conductive polymers as or carbon black as dispersed phase). Moreover, practical commercial applications are described.
... Amylose is a linear polymer of (1,4) linked anhydroglucose units (AGU). Amylopectin is a highly branched polysaccharide composed of linear (1,4) AGU chains with branch points having (1,6) linkages between amylose chains. Starch obtains its plastic properties upon the gelatinization and destructuring of starch granules with enough water and thermomechanical energy. ...
... Around the critical concentration or percolation threshold, a small increase in the concentration of the carbon black increases the conductivity by several orders of magnitude. The percolation threshold of electroactive polymer composites usually range between 10 and 30% w/w [6]. ...
... Adhesion and cohesion has been shown to lead to lower percolation thresholds (i.e. lower loading of conducting material giving higher conductivity) and improved mechanical properties in composites [6]. One should also note that the initial conductivity of TPS is relatively high compared to polypropylene (10 -11 S/cm). ...
... Such an approach allows the achievement of a very low percolation threshold, which results from the selective localization of the carbon black particles at the interface between polystyrene and polyethylene phases, thus allowing the formation of conductive pathways of carbon black particles with very low contents of filler. Parameters such as the physical properties of the filler, polymeric matrix morphology, and dispersion characteristics of the filler within the matrix should be controlled to produce composites with low percolation points [35][36][37]. Hence, some aspects concerning the morphology of CPMCB and their composites are presented, to obtain a better understanding of the electrical behavior of such materials. ...
... The increase in tensile strength (Fig. 5A) and decrease in strain at break (Fig. 5B) with increasing concentration of KPO in the composites indicate a reinforcing effect promoted by the addition of the filler in the elastomeric matrix. This effect is explained considering that incorporating particulate fillers in a polymeric matrix leads to an excessive increase in the melt viscosity during processing [36]. In the case of carbon black-filled elastomers, this increase occurs as a result of specific interactions between the matrix and the filler as well as an anchoring effect, where the elastomeric chains attach to the filler surface [38]. ...
Thermally stable elastomeric composites based on ethylene–propylene–diene monomer (EPDM) and conducting polymer-modified carbon black (CPMCB) additives were produced by casting and crosslinked by compression molding. CPMCB represent a novel thermally stable conductive compound made via “in situ” deposition of intrinsically conducting polymers (ICP) such as polyaniline or polypyrrole on carbon black particles. Thermogravimetric analysis showed that the composites are thermally stable with no appreciable degradation at ca. 300°C. Incorporating CPMCB has been found to be advantageous to the processing of composites, as the presence of ICP lead to a better distribution of the filler within the rubber matrix, as confirmed by morphological analysis. These materials have a percolation threshold range of 5–10 phr depending on the formulation and electrical dc conductivity values in the range of 1 × 10−3 to 1 × 10−2 S cm−1 above the percolation threshold. A less pronounced reinforcing effect was observed in composites produced with ICP-modified additives in relation to those produced only with carbon black. The results obtained in this study show the feasibility of this method for producing stable, electrically conducting composites with elastomeric characteristics. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
... In such an array, a nanostructured organic film is deposited onto interdigitated electrodes, which are then immersed into the liquid samples and the electrical impedance of the whole system is measured [17]. Though a variety of materials can be used in the sensing units [see for instance ref. 18,19], a judicious choice of the materials may help optimize the sensor performance for specific analytes. In this work, in particular, we selected conducting polymers, sulfonated lignin and aquatic humic substances for building the sensing units. ...
... Image Tridimensional Roughness / nm Table 1) immersed into aqueous solutions with different concentrations of brominated compounds. As it is usual for films immersed into liquid samples, the capacitance decreases monotonically with the frequency [19]. Especially at lower frequencies, the electrical response of the sensing units differs from each other, which is useful for building a sensor array with high discriminating power for similar liquids. ...
The detection of the carcinogenic trihalomethanes (THM) in public water supplysystems using low-cost equipment has become an essential feature, since these compoundsmay be generated as by-products of water-treatment processes. Here we report on a sensorarray that extends the concept of an “electronic tongue†to detect small amounts ofbromoform, bromodichloromethane and dibromochloromethane, with detection limits aslow as 0.02 mg L-1. The sensor array was made up of 10 sensing units, in whichnanostructured films of conducting and natural polymers were deposited onto goldinterdigitated electrodes. The principle of detection was impedance spectroscopy, withmeasurements carried out in the range between 1 Hz to 1 MHz. Using data at 1 kHz, atwhich the electrical response varied considerably by changing the analyte, we demonstratedwith principal component analysis (PCA) that samples with the 3 brominatedtrihalomethanes can be distinguished from each other and for various concentrations.
... Zásadní podmínkou je stabilita modifi kovaného předmětu v kyselém prostředí [20]. Antikorozní aplikace částic povrchově upravených touto tenkou vrstvou jsou také předmětem výzkumu mnoha prací [21, 22]. Mechanizmus působení vodivé formy PANI na rozhraní kov/organický povlak je uveden na Obr. 2. Železo je přímo oxidováno na železité ionty, kdy železité pasivační vrstvy jsou méně rozpustné než pasivační vrstvy železnaté, a tvoří proto odolnější pasivační vrstvy. ...
Vodivé polymery včetně významného zástupce polyanilinu (PANI) patří v současné době k vysoce zkoumaným látkám v řadě oborů. Díky snadné přípravě, netoxicitě a vysoké stabilitě se zkoumá i jeho využití ve formulaci organických povlaků. Cílem této práce je vyhodnocení vlivu polyanilinových solí na korozní vlastnosti ochranných organických povlaků pomocí zrychlených korozních zkoušek a techniky lineární polarizace (LP). Polyanilinové sole byly připraveny oxidační polymerací v kyselém prostředí, kdy jako dopující kyselina byla použita kyselina fosforečná (H
... É importante citar que para blendas produzidas a partir de PVDF/ Poli(o-methoxianilina) (POMA) [8] , foi verificado um decréscimo de 4 ordens de grandeza na condutividade normalizada após 170 h de tratamento nas mesmas condições experimentais. Sabe-se que para compostos carregados com partículas condutivas, o incremento na condutividade não ocorre de maneira linear [9] . Inicialmente, a condutividade é pouco afetada pelo carregamento, mas aumenta drasticamente quando se atinge uma determinada concentração de carga na matriz polimérica. ...
Resumo: Compósitos condutores elétricos a base de poli(fluoreto de vinilideno) (PVDF) e negro de fumo modificado com polianilina (Eeonomer ®) foram preparados através do processamento por fusão. Resultados de reometria de torque indicaram que a presença de polianilina no negro de fumo é vantajosa ao processamento por fusão, reduzindo a viscosidade do fundido em comparação com a aditivação com negro de fumo puro. Compósitos contendo acima de 5% em peso de Eeonomer® apresentaram condutividade da ordem de 10-2 S/cm. Esse valor se manteve estável mesmo após tratamento térmico a 150°C por 170 h em atmosfera ambiente. Análises por calorimetria diferencial de varredura (DSC) e difração de Raios-X mostraram que o tipo e a quantidade de Eeonomer®, assim como a taxa de resfriamento da amostra, podem afetar a temperatura de fusão, o grau de cristalinidade e a fase cristalina do PVDF presente no compósito. Abstract: Conductive polymeric composites of poly(vinylidene fluoride) and carbon black modified with polyaniline were prepared via melting processing. The additivation with Eeonomers® is advantageous to the melt processing of the composites reducing the melt viscosity in comparison to the additivation with pure carbon black. The composites containing above 5%wt of Eeonomer ® exhibited electrical conductivity around 10-2 S/cm, and this value remains constant even after thermal treatment at 150 ºC during 170 h room atmosphere. Differencial Scanning Calorimetry (DSC) and X-Ray diffraction analyses showed that composites containing the β phase of PVDF could be obtained via quenching from the melt. It was also shown that the type and amount of Eeonomer® affect the crystallinity and the melting temperature of PVDF present in the composites.
... However, it has been known for a while, that difficulties associated with the processing of ICPs have limited most of the desired practical applications. Poor solubility in common solvents and infusibility, inherent to all these polymers, are the responsible for this situation [9]. ...
Macromolecular thin layers were deposited under continuous and modulated aniline-RF-plasma conditions, and by Ar-, NH3, and I2-plasmas-enhanced crosslinking of pre-deposited N-phenyl-1,4-phenylenediamine (PPD) films on optically smooth quartz substrates. Survey and high-resolution ESCA, Fourier transform infrared spectroscopy (FT-IR), UV–VIS analyses were used for the investigation of the chemical structure of the deposited films. The thermal behavior of deposited (undoped and doped) plasma-treated PPD films was characterized by TG/DTA and DSC analysis and their electrical conductivities were evaluated by using a commercial four-probe system. It was found that gas phase aniline-plasma environments induce intense molecular fragmentation processes, which result in the formation of structures that are significantly different in comparison to that of conjugated polyaniline. The plasma-mediated crosslinking approach allows the synthesis of macromolecular layers, which retain most of the structure of the starting component, and their doped versions exhibit electrical conductivities comparable to the electrical conductivities of doped conventional polyaniline.
... A second strategy is to give up on dissolusion and instead form a colloidal suspension of the material, either in small spheres or coated onto another polymer (such as latex) which is formed into small spheres. A third strategy is to use surfactants to dope and suspend the conducting material in a solvent [61]. The conducting polymer can then be evaporated from solution with its surfactants, or combined with a polymer which can be dissolved in the same solvent. ...
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003. Includes bibliographical references (p. 207-218). This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. Field emission displays (FEDs) show great promise as high performance flat panel displays. The light emission process is efficient, long lifetimes are possible with high brightness, and bright passive matrix displays can be built. Because passive matrix displays don't need a transistor backplane, it was once thought that these displays would be cheaper to fabricate than their competitors. It is now clear that this is not the case. Fabricating a transistor backplane has turned out to be less expensive than micromachining an array of uniform field emitter tips with aligned gates. Competing technologies which use an active backplane (such as active matrix liquid crystal panels) have become ubiquitous, and FED technologies developed to date have been too expensive for the consumer market. This thesis presents a new strategy for creating a low-cost field emission display. This strategy begins by creating a field emitter out of organic conductors-a class of materials mostly neglected to date for this application. The organic emitter is made by copying a non-lithographic template. The process takes 5 minutes, occurs at room temperature and at atmospheric pressure, and does not damage the template. We show that organic conductors are easy to pattern into regular patterns and can form structures which exhibit field emission, with field enhancement factors of about 100-600 times. The field emission follows a Fowler-Nordheim characteristic. Also explored are some of the properties of organic conductors in vacuum such as conductivity over time, the interaction of the organic field emitter with background gases, and the conduction mechanism. In particular, we show that oxygen degrades the emission properties of organic field emission tips, and that organic materials retain sufficient conductivity in vacuum to serve as field emitters. (cont.) The second prong of the strategy is to combine the field emitter with an inexpensive transistor. A thin-film transistor made using an organic semiconductor is used to control the emission from the field emitter. We demonstrate a circuit architecture which allows the transistor to control the field emitter without creating a micromachined gate. This architecture uses only one high voltage supply for the panel to extract and accelerate electrons toward the phosphor screen. We show that the field emitter current can be controlled over a range of about 1000:1 using only 30V. This is verified through measurements of spot brightness on a phosphor screen. We then show that using the transistor has additional advantages. The current noise is reduced by a factor of 20, and DC current degradation is eliminated for oxygen partial pressures up to 1 x 10-6 torr. A new linearized analysis is presented which explains the DC current control and noise reduction, and also estimates the work function fluctuation on the emitter tip. The experimental results are examined in the context of this analytical framework. The work in this thesis shows (1) that a field emitter can be made from an organic conductor using a simple process (2) a field emission display can be controlled without making an array of micromachined gates and (3) using a transistor has a number of advantages in addition to controlling the field emitter ... by Ioannis Kymissis. Ph.D.
... É importante citar que para blendas produzidas a partir de PVDF/ Poli(o-methoxianilina) (POMA) [8] , foi verificado um decréscimo de 4 ordens de grandeza na condutividade normalizada após 170 h de tratamento nas mesmas condições experimentais. Sabe-se que para compostos carregados com partículas condutivas, o incremento na condutividade não ocorre de maneira linear [9] . Inicialmente, a condutividade é pouco afetada pelo carregamento, mas aumenta drasticamente quando se atinge uma determinada concentração de carga na matriz polimérica. ...
Compósitos condutores elétricos a base de poli(fluoreto de vinilideno) (PVDF) e negro de fumo modificado com polianilina (Eeonomer®) foram preparados através do processamento por fusão. Resultados de reometria de torque indicaram que a presença de polianilina no negro de fumo é vantajosa ao processamento por fusão, reduzindo a viscosidade do fundido em comparação com a aditivação com negro de fumo puro. Compósitos contendo acima de 5% em peso de Eeonomer® apresentaram condutividade da ordem de 10-2 S/cm. Esse valor se manteve estável mesmo após tratamento térmico a 150degreesC por 170 h em atmosfera ambiente. Análises por calorimetria diferencial de varredura (DSC) e difração de Raios-X mostraram que o tipo e a quantidade de Eeonomer®, assim como a taxa de resfriamento da amostra, podem afetar a temperatura de fusão, o grau de cristalinidade e a fase cristalina do PVDF presente no compósito.
The interactions between polyaniline particles and polyaniline surfaces in polyester acrylate resin mixed with 1,6-hexanediol diacrylate monomer have been investigated using contact angle measurements and the atomic force microscopy colloidal probe technique. Polyaniline with different characteristics (hydrophilic and hydrophobic) were synthesized directly on spherical polystyrene particles of 10 µm in diameter. Surface forces were measured between core/shell structured polystyrene/polyaniline particles (and a pure polystyrene particle as reference) mounted on an atomic force microscope cantilever and a pressed pellet of either hydrophilic or hydrophobic polyaniline powders, in resins of various polymer:monomer ratio. A short-range purely repulsive interaction was observed between hydrophilic polyaniline (doped with phosphoric acid) surfaces in polyester acrylate resin. In contrast, interactions between hydrophobic polyaniline (doped with n-decyl phosphonic acid) were dominated by attractive forces, suggesting less compatibility and higher tendency for aggregation of these particles in liquid polyester acrylate compared to hydrophilic polyaniline. Both observations are in agreement with the conclusions from the interfacial energy studies performed by contact angle measurements.
Polyaniline is known to be a true metal, though a nanometal. Previous experimental and theoretical evidence is reviewed. Two important structural features are presented, which have not publicly been discussed so far: (a) The formation of complexes between polyaniline and metals (Cu, Fe, Zn, In, etc.) which are crucial for most practical applications of the organic metal, polyaniline; and (b) a model for the polyaniline chain structure within the smallest morphological unit, the roughly 10 nm primary particle.
accessible online here: http://www.mdpi.com/2073-4360/2/4/786#
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