Water-soluble conductive polymers

• US 4,929,389 A
• Filed: 02/12/1988
• Issued: 05/29/1990
• Est. Priority Date: 02/12/1988
• Status: Expired due to Term

• Current Assignee: University of California
• Original Assignee: United States Of America As Represented By The Department Of Energy
• Inventors: Aldissi, Mahmoud
• Primary Examiner(s): Barr, Josephine
• Application Number:
  US07/155,450
• Time in Patent Office: 837 Days
• Field of Search: 252/500, 252/512, 252/518, 526/258, 526/256, 204/59 R, 528/380, 528/490, 528/491, 528/492, 524/423, 524/422, 524/408, 524/415, 524/404, 524/405, 524/156, 524/165, 524/166, 524/167, 524/401
• US Class Current: 252/500
• CPC Class Codes: C08G 61/123 derived from five-membered heterocyclic compounds
• CPC Class Codes: H01B 1/127 comprising five-membered aromatic rings in the main chain, e.g. polypyrroles, polythiophenes

Abstract

Polymers which are soluble in water and are electrically conductive. The monomer repeat unit is a thiophene or pyrrole molecule having an alkyl group substituted for the hydrogen atom located in the beta position of the thiophene or pyrrole ring and having a surfactant molecule at the end of the alkyl chain. Polymers of this class having 8 or more carbon atoms in the alkyl chain exhibit liquid crystalline behavior, resulting in high electrical anisotropy. The monomer-to-monomer bonds are located between the carbon atoms which are adjacent to the sulfur or nitrogen atoms. The number of carbon atoms in the alkyl group may vary from 1 to 20 carbon atoms. The surfactant molecule consists of a sulfonate group, or a sulfate group, or a carboxylate group, and hydrogen or an alkali metal. Negative ions from a supporting electrolyte which may be used in the electrochemical synthesis of a polymer may be incorporated into the polymer during the synthesis and serve as a dopant to increase the conductivity.

Claims

1. An electrically conductive self-doped polymeric composition of matter having a monomer repeat unit comprising:

##STR2## where the monomer-to-monomer bonds of said polymer are located between the carbon atoms adjacent to X;

where X is chosen from a group consistng of NH and S;

where m is a whole number having a value of from 1 to 20, inclusive;

where Y is chosen from a group consisting of SO₃, SO₄, and CO₂ ; and

where A is chosen from a group consisting of hydrogen, lithium, sodium, potassium, rubidium, and cesium.

2. A composition of claim 1 having a molecular weight in the range of from about 20,000 to about 70,000.

3. A composition of claim 1 which is soluble in water.

4. A composition of claim 1 having a conductivity in the range of from about 10^-3 to about 10⁵ ohm^-1 cm^-1.

5. A composition of claim 1 containing an additional dopant to increase conductivity comprised of negative ions which are supplied from a supporting electrolyte substance utilized in synthesizing said composition.

6. A composition of claim 5 where said supporting electrolyte substance is chosen from a group comprised of tetraethylammonium para-toluenesulfonate, lithium perchlorate, tetrabutylammonium tetrafluoborate, lithium hexafluophosphate, lithium tetrafluorborate, lithium hexafluoarsenate, and tetrabutylammonium para-toluenesulfonate.

7. A composition of claim 1 having liquid crystalline properties, where X is sulfur, m has a value of 8 or 10, Y is an SO₃ group, and A is chosen from a group consisting of hydrogen, sodium, and potassium.

8. A composition of claim 7 having an electrical anisotropy of about 1000, the conductivity of the composition being about 10,000 ohm^-1 cm^-1 in a direction parallel to the orientation direction of the composition and about 10 ohm^-1 cm^-1 in a direction perpendicular to the orientation direction of the composition.

9. A composition of claim 1 which is additionally doped to increase conductivity by exposure to sulfuric acid or arsenic pentafluoride.