Polystyrene electrical conductivity

In this context numerous changes were made. The chapter Properties of Polymers was revised and a new section Correlations of Structure and Morphology with the Properties of Polymers was added. The chapter Characterization of Macromolecules was revised and enlarged. 15 examples have been deleted as they did no longer represent the state of the art and/or were of minor educational value. Several new experiments (plus background text) were added, as, for example controlled radical polymerization - enzymatic polymerization - microemulsions - polyelectrolytes as superabsorbants - hyperbranched polymers - new blockcopolymers - high impact polystyrene - electrical conducting polymers. 

Let us first assume that we have a spherical particle with a radius of 5 p.m similar to an idealized toner particle, which is comprised of polystyrene, in contact with an electrically conducting substrate. A typical electric charge on a toner particle of that size is of the order of 10" " C. The Hamaker coefficient (Eq. 15) for such as system would be about 1.5 eV. 

Fig. 6.7 (a) The variation of electrical conductivity of PVA-EG hybrid with increasing graphene content. Inset shows the dependence of dielectric constant for the hybrid, (b) The variation of conductivity of the polystyrene-graphene hybrid with filler content. Inset shows the four probe setup for in-plane and transverse measurements and the computed distributions of the current density for in-plane condition (reference [8]). 

Ionic conductivity can be found in polyelectrolytes such as the salts of polyacrylic acid, sulfonated polystyrene or quaternized polvamines (ion-exchange resins). When dry, these materials have low conductivities. However, in tiie presence of small amounts of polar solvents or water—some of these polyelectrolytes are somewhat hygroscopic electrical conductivity can be observed. The currents are earned by ions (protons, for instance). Such systems can only be used in cases where very small currents are expected. Large currents would result in observable electrochemical changes of the materials, In applications as antistatic electricity coatings, conductivities of 10-b ohm-1 cm-1 are sufficient,... 

PPy may be similarly coated on low-density polyethylene (LDPE), whereas grafting of the LPDE surface with acrylic acid enhances film growth and adhesion.86 The in situ oxidation of pyrrole by Fe(III) can also be used to deposit PPy films on polystyrene substrates.87 In a variation of this method, polyimide films exhaustively soaked in pyrrole (with up to 14% monomer uptake) have been coated with PPy via oxidation with FeCl3 in acetonitrile solvent.88 The resultant material shows electrical conductivity of ca. 4 x 10 2 S cm-1. 

Aniline can also be polymerized by horseradish peroxidase and hydrogen peroxide to electrically conducting polymers.331 If run in the presence of sulfonated polystyrene, this leads to a water-soluble doped polymer in a one-pot, benign process. Horseradish peroxidase and hy-... 

Electrically conducting polystyrene/polythiophene, polystyrene/polypyrrole, polyacrylonitrUe/poly-pyrrole, polycarbonate/polythiophene, polycarbonate/polypyrrole composites are prepared by... 

S. Nair, E. Hsiao, and S. H. Kim Fabrication of electrically-conducting nonwoven porous mats of polystyrene-polypyrrole core-shell nanofibers via electrospinning and vapor phase polymerization, J. Mater. Chem., 18, 5155-5161 (2008). 

Most polymers (typified by polystyrene and polyethylene) are electrically insulating and have conductivities doped with iodine to become electrically conducting (values have now been reported up to olO Scm ) represented a pivotal discovery in polymer science that ultimately resulted in the award of the Nobel Prize for Chemistry in 2000 [4]. The study of electrically conducting polymers is now well advanced and two extremes in the continuum of transport mechanisms exist. If the charge carriers are present in delocalized orbitals that form a band structure along the polymer backbone, they conduct by a delocalization mechanism. In contrast, isolated groups in a polymer can function as acceptors or donors of electrons and can permit... 

M. Mahmoodi, M. Arjmand, U. Sundararaj, S. Park, The Electrical Conductivity and Electromagnetic Interference Shielding of Injection Molded Multi-waUed Carbon Nanotube/Polystyrene Composites. Carbon 2012, 50,1455-1464. 

Electrospinning is applicable to a wide range of polymers like those used in conventional spinning, that is, polyolefine, polyamides, polyester, aramide, and acrylic, as well as biopolymers like proteins, DNA, and polypeptides, or others like electrically conducting, photonic and other polymers such as poly(ethylene oxide] (PEO], DNA, poly(acrylic acid] (PAA], polyQactic acid] (PEA], and also collagen, organics such as nylon, polyester, and acryl resin, and poly(vinyl alcohol] (PVA], polystyrene (PS], polyacrylonitrile (PAN], peptide, cellulose, etc. 

Composite conductive fibers based on poly(3,4-ethylene-diox)d hiophene]-polystyrene sulfonic acid (PEDOT-PSS) solution blended with polyacrylonitrile (PAN] were obtained via wet spinning. The influence of draw ratio on the morphology, structure, thermal degradation, electrical conductivity, and mechanical properties of the resulting fibers was investigated. The results revealed that the PEDOT-PSS/PAN composite conductive fibers crystallization, electrical conductivity and mechanical properties were improved with the increase of draw ratio. The thermal stability of the fibers was almost independent of draw ratio, and only decreased slightty with draw ratio. Besides, when the draw ratio was 6, the conductivity of the PEDOT-PSS/PAN fibers was 5.0 S cm, ten times the conductivity when the draw ratio was 2 (Fig 5.10]. ... 

In situ polymerization to prepare immiscible blends was pioneered by Watkins and McCarthy [108], stimulating other researchers to apply this methodology to prepare novel polymer blends [109-112], fiber-reinforced composite materials[39], and electrically conducting composites [66, 67, 113-116]. Polymer blends produced in this manner include polystyrene/poly(vinyl chloride) [117, 118], polysty-rene/PET [119], nanometer-dispersed polypropylene/polystyrene interpenetrating networks [120], polypropylene/polystyrene [121] and polyethylene/polystyrene [122]. The resultant polymer blend may have a unique morphology compared to the traditionally prepared counterpart (if it is feasible to prepare such a blend via conventional procedures) and therefore demands a thorough investigation. 

Fig. 6.9 Functional polymer nano-composites left, well-dispersed Ti02 nano-particles in a polystyrene matrix for increasing the composite s refractive index, right, percolating carbon-black nano-particles in a carbonate matrix to realize an electrically conducting material...

Three-layered nanoparticles containing an hbPG core and cross-linked block copolymers based on N-isopropyl acrylate and N,N-dimethylaminoethyl acrylate as the respective arms were synthesized and proved to be thermoresponsive. ° Chu and co-workers" reported electrically conductive core-shell nanoparticles based on poly(n-butylacrylate-b-polystyrene) multiarm star polymers. The PS segments were converted to poly(p-styrenesulfonate) (PSS), thus generating amphiphilic tmimolecular micelles. Then the oxidative propagation of 3,4-ethylenedioxythiophene (EDOT) on the PSS chains was carried out by counterion-induced polymerization to produce a stable aqueous dispersion of the respective PEDOT complex. 

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