Title of Invention	A PROCESS FOR THE PREPARATION OF DOPED CONDUCTING POLYMER FILM
Abstract	This invention relates to a process for preparation of doped conducting polymer film. More particularly it relates to deposition of polyaniline films on negatively charged electrode in an electrochemical bath. The process comprises of coating a substrate with an adhesion promoter film, depositing the conducting metal film on a substrate, characterized in that placing the metal coated substrate in an electrochemical cell with three electrode configuration having reference, counter and working electrode and an electrolyte containing 0.01 to 0.5 mol of monomer, protonic acid and .001 to 2.0 mole of an initiator, applying a steady negative potential of-0.3 to -1.1 Volts for a period ranging between 30 to 150 min to obtain the desired polyaniline film deposited on the cathode.

Title of Invention

A PROCESS FOR THE PREPARATION OF DOPED CONDUCTING POLYMER FILM

Abstract

This invention relates to a process for preparation of doped conducting polymer film. More particularly it relates to deposition of polyaniline films on negatively charged electrode in an electrochemical bath. The process comprises of coating a substrate with an adhesion promoter film, depositing the conducting metal film on a substrate, characterized in that placing the metal coated substrate in an electrochemical cell with three electrode configuration having reference, counter and working electrode and an electrolyte containing 0.01 to 0.5 mol of monomer, protonic acid and .001 to 2.0 mole of an initiator, applying a steady negative potential of-0.3 to -1.1 Volts for a period ranging between 30 to 150 min to obtain the desired polyaniline film deposited on the cathode.

Full Text	This invention relates to a process for preparation of doped conducting polymer film. More particularly it relates to deposition of polyaniline films on negatively charged electrode in an electrochemical bath. Conducting polymers are increasingly being used for different electronic devices such as sensors, light emitting diodes etc. In these devices the conducting polymer is desired in the form of thin films deposited on conducting or insulating substrates. It is now well established that conducting polyaniline can be deposited on conducting substrates by electrochemical technique using monomers and supporting electrolytes and applying a particular potential. The conventional process comprises, placing 0.1 M aniline in 0.1 M hydrochloric acid in 100 ml distilled water, placing conducting metal electrode with counter electrode and applying a potential of 0.7 to 0.8 Volts (positive) for 3 to 4 min to obtain polyaniline films. However, it is invariably found that the conducting polymer film is formed on the anode i.e. on the electrode having the positive potential. In these conventional techniques there is no polymer deposit found on the cathode. It is often advantageous to obtain a deposit on negatively charged substrate rather than the positive one, since the ions in electrolyte may be selectively introduced in such films more easily. In the conventional method, the dopant ion gets simultaneously incorporated in the films which are formed on the anode. One has to subject these films to negative potential so as to remove ( or de-dope) the ions and then place the films in another bath so as to selectively dope ( or re-dope) the films with desired ions. This leads to large number of steps and subjecting the films to a number of electrochemical cycles causing Possible damage. There is no process reported earlier for the cathodic deposition of conducting polymer and in particular polyaniline on the cathodes. The main object of this invention is to provide a process for the preparation of conducting polyaniline film directly on the cathodes. Accordingly, the present invention provides a process for the preparation of doped conducting polymer film which comprises; coating a substrate with an adhesion promoter film, depositing the conducting metal film of the kind as herein described on a substrate, characterized in that placing the metal coated substrate in an electrochemical cell with three electrode configuration having reference, counter and working electrode and an electrolyte containing polar solvent, 0.01 to 0.5 mol of monomer, protonic acid and .001 to 2.0 mole of an initiator, applying a steady negative potential of-0.3 to -1.1 Volts for a period ranging between 30 to 150 min to obtain the desired polyaniline film deposited on the cathode. In an embodiment of the present invention the substrate used is select4ed from the group consisting of high conducting glass, polyester film coated with metallic film, metal foils or sheets having smooth surface with electrical conductivity higher than 10 S/cm. In an another embodiment the adhesion promoting layer sued is a polymer film selected from the group consisting of polyvinyl butyral, copolymer of styrene butadiene, polyvinyl formal, polyvinyl acetate. In yet another embodiment the electrolyte used contains polar solvent with high dielectric constant of more than 30 selected from the group consisting of water, n-methyl pyrrolidone, di-methyl sulfoxide, di-methyl formamide and acetonitrile. In yet another embodiment the protonic acid used is selected from the group consisting of sulfonic acid derivatives, hydrochloric acid and sulfuric acid. In yet another embodiment the monomer used is selected from the group consisting of aniline, substituted aniline, anisidine and toluidine. In yet another embodiment the concentration of monomer used is preferably in the range of 0.1 to 0.2mol. In yet another embodiment the initiator used is selected from the group consisting of oxidising salts containing persulfate, dichromate and peroxy radicals, which is in the In In yet another embodiment concentration range of 0.001 to 2.0 moles preferably 0.1 to 0.2 mole per litre of solvent. In yet another embodiment the concentration of initiator used is preferably in the range of 0.1 to 0.2mol. In still another embodiment the potential applied to the electrode is preferably in the range of -0.3 to -0.5 V with respect to reference electrode The process of the present invention is described hereinbelow with examples, which are illustrative only and should not be construed to limit the scope of the invention in any manner. EXAMPLE -1 In a three electrode single compartment electrochemical cell were placed 150 ml of distilled water in which 2 ml of aniline and 11 ml of concentrated hydrochloric acid (35%). The polished platinum foil substrate, counter electrode and the reference electrodes were then dipped in the electrolyte, connected to computer controlled potentiostat and a potential of-0.4 V (vs.SCE)was applied. The ammonium per sulfate (5.3 g) dissolved in 10 ml distilled water was then poured in the electrolyte with stirring within 10 seconds. The potential was maintained at the same level for 45 min to give a dark green deposit on the cathode. The deposit film was having characteristics as given in Table-1 . EXAMPLE-2 Clean microscopic glass plates were dip coated with 1% solution of styrene butadiene copolymer , dried and then placed in vacuum chamber. Gold films were deposited on the pretreated glass substrates at vacuum better than 10 -5 torr by conventional thermal evaporation technique. The gold film coated glass plates were then placed in the three electrode single compartment electrochemical cell containing 150 ml distilled water, 2 ml aniline and 11 ml hydrochloric acid (35%) together with counter electrode and reference electrode. The electrolyte was cooled to 10 °C and a potential of-0.3 V was applied by means of computer controlled potentiostat. Ammonium persulfate (2.56 gms) disolved in 10 ml distilled water were then poured instantly in the electrolyte. The potential was maintained at -0.3 Volts (vs SCE) for 45 min to obtain a thick green deposit of polyaniline on the cathode. The characteristics of these films are given in Table - 1. EXAMPLE -3 In a three electrode single compartment electrochemical cell, 100 ml of distilled water, 5 ml sulfuric acid and 2.0 ml aniline were poured. A polished platinum foil, counter electrode and reference SCE electrode were placed in the electrolyte. A potential of-0.3 Volts (vs SCE) was applied and then 1.1 gm of potassium dichromate dissolved in 50 ml water were added to the cell. The potential was held a constant value of-0.3 volts for 2.0 hrs to give a bluish green deposit of polyaniline on the cathode. The characteristics of these films are given in Table - 1 . Table- 1 : Characteristics of the cathodically deposited polyaniline films (Table Removed) The above observations clearly indicate that substantial polyaniline ( as detected by the characteristic absorption) is found to be deposited on the cathode by the process described in the present invention. No deposit is found on the cathode when the electrolyte is not modified as well as when the conventional process is used. The main advantage of the present invention is that the conducting polymer is formed on the cathode and under negative applied potentials at which very little oxidation of the metallic substrates takes place Claim: 1. A process for the preparation of doped conducting polymer film which comprises; coating a substrate with an adhesion promoter film, depositing the conducting metal film of the kind as herein described on a substrate, characterized in that placing the metal coated substrate in an electrochemical cell with three electrode configuration having reference, counter and working electrode and an electrolyte containing polar solvent, 0.01 to 0.5 mol of monomer, protonic acid and .001 to 2.0 mole of an initiator, applying a steady negative potential of-0.3 to -1.1 Volts for a period ranging between 30 to 150 min to obtain the desired polyaniline film deposited on the cathode. 2. A process as claimed in claim 1 wherein, the substrate used is selected from the group consisting of high conducting glass, polyester film coated with metallic film, metal foils or sheets having smooth surface with electrical conductivity higher than 10 S/cm. 3. A process as claimed in claims 1 and 2 wherein, the adhesion promoting layer used is a polymer film selected from the group consisting of polyvinyl butyric, copolymer of styrene butadiene, polyvinyl formal, polyvinyl acetate. 4. A process as claimed in claims 1 to 3 wherein, the electrolyte used contains polar solvent with high dielectric constant above 30 selected form the group consisting of water, n-methyl pyrrolidone, di-methyl sulfoxide, di-methyl formamide and acetonitrile. 5. A process as claimed in claims 1 to 4, wherein the protonic acid used is selected from the group consisting of sulfonic acid derivatives, hydrochloric acid and sulfuric acid. 6. A process as claimed in claims 1 to 5, wherein the monomer used is selected from the group consisting of aniline, substituted aniline, anisidine and toluidine. 7. A process as claimed in claims 1 to 6, wherein the concentration of monomer used is preferably in the range of 0.1 to 0.2 mol. 8. A process as in claims 1 to 7, wherein the initiator used is selected from the group consisting of oxidizing salts containing persulfate, dichromate and peroxy radicals in the concentration range of 0.001 to 2.0 moles preferably 0.1 to 0.2 moles per litre of solvent. 9. A process as claimed in claims 1 to 8, wherein the potential applied to the electrode is preferably in the range of -0.3 to -0.5 V with respect to reference electrode. 10. A process for the preparation of doped conducting polymer film substantially as herein described with reference to examples.

Full Text

This invention relates to a process for preparation of doped conducting polymer film. More particularly it relates to deposition of polyaniline films on negatively charged electrode in an electrochemical bath.
Conducting polymers are increasingly being used for different electronic devices such as sensors, light emitting diodes etc. In these devices the conducting polymer is desired in the form of thin films deposited on conducting or insulating substrates. It is now well established that conducting polyaniline can be deposited on conducting substrates by electrochemical technique using monomers and supporting electrolytes and applying a particular potential. The conventional process comprises, placing 0.1 M aniline in 0.1 M hydrochloric acid in 100 ml distilled water, placing conducting metal electrode with counter electrode and applying a potential of 0.7 to 0.8 Volts (positive) for 3 to 4 min to obtain polyaniline films. However, it is invariably found that the conducting polymer film is formed on the anode i.e. on the electrode having the positive potential.
In these conventional techniques there is no polymer deposit found on the cathode.
It is often advantageous to obtain a deposit on negatively charged substrate rather than the positive one, since the ions in electrolyte may be selectively introduced in such films more easily. In the conventional method, the dopant ion gets simultaneously incorporated in the films which are formed on the anode. One has to subject these films to negative potential so as to remove ( or de-dope) the ions and then place the films in another bath so as to selectively dope ( or re-dope) the films with desired ions. This leads to large number of steps and subjecting the films to a number of electrochemical cycles causing
Possible damage. There is no process reported earlier for the cathodic deposition of conducting polymer and in particular polyaniline on the cathodes.
The main object of this invention is to provide a process for the preparation of conducting polyaniline film directly on the cathodes.
Accordingly, the present invention provides a process for the preparation of doped conducting polymer film which comprises; coating a substrate with an adhesion promoter film, depositing the conducting metal film of the kind as herein described on a substrate, characterized in that placing the metal coated substrate in an electrochemical cell with three electrode configuration having reference, counter and working electrode and an electrolyte containing polar solvent, 0.01 to 0.5 mol of monomer, protonic acid and .001 to 2.0 mole of an initiator, applying a steady negative potential of-0.3 to -1.1 Volts for a period ranging between 30 to 150 min to obtain the desired polyaniline film deposited on the cathode.
In an embodiment of the present invention the substrate used is select4ed from the group consisting of high conducting glass, polyester film coated with metallic film, metal foils or sheets having smooth surface with electrical conductivity higher than 10 S/cm.
In an another embodiment the adhesion promoting layer sued is a polymer film selected from the group consisting of polyvinyl butyral, copolymer of styrene butadiene, polyvinyl formal, polyvinyl acetate.
In yet another embodiment the electrolyte used contains polar solvent with high dielectric constant of more than 30 selected from the group consisting of water, n-methyl pyrrolidone, di-methyl sulfoxide, di-methyl formamide and acetonitrile.
In yet another embodiment the protonic acid used is selected from the group consisting of sulfonic acid derivatives, hydrochloric acid and sulfuric acid.
In yet another embodiment the monomer used is selected from the group consisting of aniline, substituted aniline, anisidine and toluidine.
In yet another embodiment the concentration of monomer used is preferably in the range of 0.1 to 0.2mol.
In yet another embodiment the initiator used is selected from the group consisting of oxidising salts containing persulfate, dichromate and peroxy radicals, which is in the In
In yet another embodiment concentration range of 0.001 to 2.0 moles preferably 0.1 to 0.2 mole per litre of solvent.
In yet another embodiment the concentration of initiator used is preferably in the range of 0.1 to 0.2mol.
In still another embodiment the potential applied to the electrode is preferably in the range of -0.3 to -0.5 V with respect to reference electrode
The process of the present invention is described hereinbelow with examples, which are illustrative only and should not be construed to limit the scope of the invention in any manner.
EXAMPLE -1 In a three electrode single compartment electrochemical cell were placed 150 ml of distilled water in which 2 ml of aniline and 11 ml of concentrated hydrochloric acid (35%). The polished platinum foil substrate, counter electrode and the reference electrodes were then dipped in the electrolyte, connected to computer controlled potentiostat and a potential of-0.4 V (vs.SCE)was applied. The ammonium per sulfate (5.3 g) dissolved in 10 ml distilled water was then poured in the electrolyte with stirring within 10 seconds. The potential was maintained at the same level for 45 min to give a dark green deposit on the cathode. The deposit film was having characteristics as given in Table-1 .
EXAMPLE-2 Clean microscopic glass plates were dip coated with 1% solution of styrene butadiene copolymer , dried and then placed in vacuum chamber. Gold films were deposited on the pretreated glass substrates at vacuum better than 10 -5 torr by conventional thermal evaporation technique. The gold film coated glass plates were then placed in the three electrode single compartment electrochemical cell containing 150 ml distilled water, 2 ml aniline and 11 ml hydrochloric acid (35%) together with counter electrode and reference
electrode. The electrolyte was cooled to 10 °C and a potential of-0.3 V was applied by means of computer controlled potentiostat. Ammonium persulfate (2.56 gms) disolved in 10 ml distilled water were then poured instantly in the electrolyte. The potential was maintained at -0.3 Volts (vs SCE) for 45 min to obtain a thick green deposit of polyaniline on the cathode. The characteristics of these films are given in Table - 1.
EXAMPLE -3
In a three electrode single compartment electrochemical cell, 100 ml of distilled water, 5 ml sulfuric acid and 2.0 ml aniline were poured. A polished platinum foil, counter electrode and reference SCE electrode were placed in the electrolyte. A potential of-0.3 Volts (vs SCE) was applied and then 1.1 gm of potassium dichromate dissolved in 50 ml water were added to the cell. The potential was held a constant value of-0.3 volts for 2.0 hrs to give a bluish green deposit of polyaniline on the cathode. The characteristics of these films are given in Table - 1 .
Table- 1 : Characteristics of the cathodically deposited polyaniline films
(Table Removed)
The above observations clearly indicate that substantial polyaniline ( as detected by the characteristic absorption) is found to be deposited on the cathode by the process described in the present invention. No deposit is found on the cathode when the electrolyte is not modified as well as when the conventional process is used.
The main advantage of the present invention is that the conducting polymer is formed on the cathode and under negative applied potentials at which very little oxidation of the metallic substrates takes place

Claim:
1. A process for the preparation of doped conducting polymer film which comprises; coating a substrate with an adhesion promoter film, depositing the conducting metal film of the kind as herein described on a substrate, characterized in that placing the metal coated substrate in an electrochemical cell with three electrode configuration having reference, counter and working electrode and an electrolyte containing polar solvent, 0.01 to 0.5 mol of monomer, protonic acid and .001 to 2.0 mole of an initiator, applying a steady negative potential of-0.3 to -1.1 Volts for a period ranging between 30 to 150 min to obtain the desired polyaniline film deposited on the cathode.
2. A process as claimed in claim 1 wherein, the substrate used is selected from the group consisting of high conducting glass, polyester film coated with metallic film, metal foils or sheets having smooth surface with electrical conductivity higher than 10 S/cm.
3. A process as claimed in claims 1 and 2 wherein, the adhesion promoting layer used is a polymer film selected from the group consisting of polyvinyl butyric, copolymer of styrene butadiene, polyvinyl formal, polyvinyl acetate.
4. A process as claimed in claims 1 to 3 wherein, the electrolyte used contains polar solvent with high dielectric constant above 30 selected form the group consisting of water, n-methyl pyrrolidone, di-methyl sulfoxide, di-methyl formamide and acetonitrile.
5. A process as claimed in claims 1 to 4, wherein the protonic acid used is selected from the group consisting of sulfonic acid derivatives, hydrochloric acid and sulfuric acid.
6. A process as claimed in claims 1 to 5, wherein the monomer used is selected from the group consisting of aniline, substituted aniline, anisidine and toluidine.
7. A process as claimed in claims 1 to 6, wherein the concentration of monomer used is preferably in the range of 0.1 to 0.2 mol.
8. A process as in claims 1 to 7, wherein the initiator used is selected from the group consisting of oxidizing salts containing persulfate, dichromate and peroxy radicals
in the concentration range of 0.001 to 2.0 moles preferably 0.1 to 0.2 moles per litre of solvent.
9. A process as claimed in claims 1 to 8, wherein the potential applied to the electrode is preferably in the range of -0.3 to -0.5 V with respect to reference electrode.
10. A process for the preparation of doped conducting polymer film substantially as herein described with reference to examples.

Documents:

1102-del-2001-abstract.pdf

1102-del-2001-claims.pdf

1102-del-2001-correspondence-others.pdf

1102-del-2001-correspondence-po.pdf

1102-del-2001-description (complete).pdf

1102-del-2001-form-1.pdf

1102-del-2001-form-18.pdf

1102-del-2001-form-2.pdf

1102-del-2001-form-3.pdf

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Patent Number

253331

Indian Patent Application Number

1102/DEL/2001

PG Journal Number

29/2012

Publication Date

20-Jul-2012

Grant Date

12-Jul-2012

Date of Filing

31-Oct-2001

Name of Patentee

COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH

Applicant Address

RAFI MARG, NEW DELHI-110001, INDIA

Inventors:

#	Inventor's Name	Inventor's Address
1	SUBRAMANIAM RADHAKRISHNAN	NATIONAL CHEMICAL LABORATORY, PUNE 411008, (MAHARASTRA) INDIA
2	SHRIPAD DAGADOPANT DESHPANDE	NATIONAL CHEMICAL LABORATORY, PUNE 411008, (MAHARASTRA) INDIA

PCT International Classification Number

G01N 27/333

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA