Compositions – Electrically conductive or emissive compositions
Patent
1991-12-02
1994-01-18
Lieberman, Paul
Compositions
Electrically conductive or emissive compositions
252518, 2641761, 264211, H01B 1300, C08L 6500
Patent
active
052797694
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a method for preparing a conductive polymer by doping a conductor polymer.
Plastics and other polymers do not by themselves conduct electricity, but they can be made conductive for various applications. Electrically active or conductive polymers can be prepared from organic polymers having long chains of conjugated double bonds. The silicon electrodes in the double bonds can be "disturbed" by adding to the polymer certain doping agents, which either receive or donate electrons. Openings or extra electrons then arise in the polymer chain, which make the passage of electric current along the conjugated chain possible. The conductivity of polymers can be adjusted depending on the doping agent content such that it covers nearly the entire conductivity range from insulators to metals. Such conductive polymers have many interesting applications, e.g. in the manufacture of light batteries and accumulators.
Polythiophene is one of the polymers, which can be made electrically active in the above-mentioned manner. Polythiophene can be prepared for example by using Ziegier-type catalysts and acidic initiators.
The usability of electrically active polymers is dependent e.g. on their stability properties. Polythiophene is in a reduced pure form very stable in different conditions, such as in air, moisture, vacuum and at high temperatures. The stability of a conductive polythiophene is, by contrast, in different conditions dependent on the doping agent anion used. The polythiophene complexes known previously are more or less unstable and thereby questionable for many applications. According to an earlier patent application by the applicant, "A conductive polythiophene and a method for its preparation and its usage" (FI-852883), a more stable conductive polythiophene polymer is prepared by doping and treating it with FeCl.sub.3. According to the application, this doping is performed by means of a solvent or a suspension medium. After the doping, the membrane obtained is washed clean from the extra doping agent.
After the doping, the polymer is generally insoluble and it can no longer be formed, due to which doping has traditionally been performed subsequently after the forming of the polymer.
As known, the doping of polymers thus occurs after the treatment, or after the formation of the product, e.g. in the manner described above with FeCl.sub.3. Such a method becomes very expensive because of special devices designed for doping, and furthermore, it is unpractical and non-pro-environmental, since toxic volatile gases spread to the environment.
Prior art is also described in the U.S. Pat. No. 4,557,807 and EP patent application 0 168 621 A2, which present devices and methods for preparing conductor polymers by coating the polymer with a conductive coating, which is brought onto a pretreated polymer membrane placed in a form with an electrical layering method.
As previously mentioned, conductive polymers are polyconjugated systems. The properties of conductive polymers include a high crystallinity, and their color is generally mat-black. Conductive polymeric and organic conductors are generally speaking insoluble, it is not possible to melt or form them, and in certain cases, they are unstable against oxygen, moisture and high temperatures, due to which also doping at high temperatures has previously not succeeded. Until now, it has therefore not been possible to treat or form conductor polymers thermoplastically in any way. There are descriptions of the meltability of some single conductor polymers, but their conductivity has been very poor.
Methods have been presented, in which gel-like polymer mixtures containing a solvent are pressed and dried and thereafter calendered. However, the final product still contains an amount of the solvent, see e.g. EP-26235 and GB-2072197.
For solving the problem, attempts have also been made to develop special polymerization methods, and mixtures of conductor polymers and other polymers have been formed, which could be formed after doping. The conductivity has, h
REFERENCES:
patent: 4568482 (1986-02-01), Jenekhe et al.
patent: 4935164 (1990-06-01), Wessling et al.
patent: 5110669 (1992-05-01), Knobel et al.
patent: 5151221 (1992-09-01), sterholm et al.
patent: 5171478 (1992-12-01), Han
Karna Toivo
Kokkonen Timo
Laakso Jukka
Nyholm Per
sterholm Jan-Erik
Lieberman Paul
Neste Oy
Swope Bradley A.
LandOfFree
Method for preparing a conductive polymer does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for preparing a conductive polymer, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for preparing a conductive polymer will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1134568