Oxidative/reductive methods of deaggregation of electrically con

Details Oxidative/reductive methods of deaggregation of electrically con Oxidative/reductive methods of deaggregation of electrically con

1998-07-27

2000-10-31

Seidleck, James J.

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Nitrogen-containing reactant

528228, 528229, 525540, 525422, C08G 7300

Patent

active

061404624

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

The present invention is directed to oxidative and reductive methods of fabricating electrically conducting polymers and precursors thereof and methods of fabricating articles therewith in which the polymer chains are deaggregated. Such deaggregated conducting polymers and precursors thereof exhibit better processability and higher electrical conductivity than do the corresponding aggregated polymers.


BACKGROUND OF THE INVENTION

Electrically conductive organic polymers have been of scientific and technological interest since the late 1970's. These relatively new materials exhibit the electronic and magnetic properties characteristic of metals while retaining the physical and mechanical properties associated with conventional organic polymers. Herein we describe electrically conducting polymers, for example polyparaphenylene vinylenes, polyparaphenylenes, polyanilines, polythiophenes, polyazines, polyfuranes, polypyrroles, polyselenophenes, poly-p-phenylene sulfides, polythianapthenes, polyacetylenes formed from soluble precursors, combinations thereof and blends thereof with other polymers and copolymers of the monomers thereof.
These polymers are conjugated systems which are made electrically conducting by doping. The non-doped or non-conducting form of the polymer is referred to herein as the precursor to the electrically conducting polymer. The doped or conducting form of the polymer is referred to herein as the conducting polymer.
Conducting polymers have potential for a large number of applications in such areas as electrostatic charge/discharge (ESC/ESD) protection, electromagnetic interference (EMI) shielding, resists, electroplating, corrosion protection of metals and ultimately metal replacements, i.e. wiring, plastic microcircuits, conducting pastes for various interconnection technologies (solder alternative) etc.. Many of the above applications especially those requiring high current capacity have not yet been realized because the conductivity of the processable conducting polymers is not yet adequate for such applications. In order for these materials to be used in place of metals in more applications, it is desirable to increase the conductivity of these materials. In addition, the processability of these polymers also requires improvement. Although some of these polymers are soluble, the solubility is generally limited and the solutions tend to be not stable over time.
The polyaniline class of conducting polymers has been shown to be one of the most promising and most suited conducting polymers for a broad range of commercial applications. The polymer has excellent environmental stability and offers a simple, one-step synthesis. However, the conductivity of the material in its most general form (unsubstituted polyaniline doped with hydrochloric acid) is generally on the low end of the metallic regime most typically, on the order of 1 to 10 S/cm (A. G. Macdiarmid and A. J. Epstein, Faraday Discuss. Chem. Soc. 88, 317, 1989). In addition, the processability of this class of polymers requires improvement. Although polyaniline is a soluble polymer, it has been noted that the solutions tend to be unstable with time. (E. J. OH et al, Synth. Met. 55-57, 977 (1993). Solutions of for example the polyaniline in the non-doped form tend to gel upon standing. Solutions greater than 5% solids concentration tend to gel within hours limiting the applicability of the polymer. It is desirable to devise methods of increasing the electrical conductivity of the doped polyanilines and to enhance the processability of these systems to allow broader applicability.
The conductivity (.sigma.) is dependent on the number of carriers (n) set by the doping level, the charge on the carriers (q) and on the mobility (g) (both interchain and intrachain mobility) of the carriers. thus, the conductivity is dependent on the mobility of the carriers. To achieve higher conductivity, the mobility in these systems needs to be increased. The mobility, in turn, depends on the morphology of the polymer. The

REFERENCES:
patent: 5258472 (1993-11-01), MacDiarmid et al.

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