Title of Invention	A PROCESS FOR THE PREPARATION OF NOVEL ALKYL-CYCLOALKYL THIOPHENE COPOLYMERS USEFUL FOR LIGHT EMITTING DIODE APPLICATIONS
Abstract	The present invention provides a process for the preparation of novel alkyl-cycloalkyl thiophene copolymers useful for light emitting diode applications, which comprises synthesising cycloalkyl thiophene and alkyl thiophene by known methods, copolymerising alkyl thiophene and cycloalkyl thiophene in a ratio ranging from 1:0.1 to 1:10 in an organic solvent in inert atmosphere in the presence of an oxidising agent in the range of 1-5 moles per mole of monomer mixture at a temperature in the range of 0-30 C for a period ranging 3-48 hrs; precipitating the copolymer formed with non solvent as herein described ;extracting the copolymer by known method.The copolymer is useful for light emitting diode applications .

Title of Invention

A PROCESS FOR THE PREPARATION OF NOVEL ALKYL-CYCLOALKYL THIOPHENE COPOLYMERS USEFUL FOR LIGHT EMITTING DIODE APPLICATIONS

Abstract

The present invention provides a process for the preparation of novel alkyl-cycloalkyl thiophene copolymers useful for light emitting diode applications, which comprises synthesising cycloalkyl thiophene and alkyl thiophene by known methods, copolymerising alkyl thiophene and cycloalkyl thiophene in a ratio ranging from 1:0.1 to 1:10 in an organic solvent in inert atmosphere in the presence of an oxidising agent in the range of 1-5 moles per mole of monomer mixture at a temperature in the range of 0-30 C for a period ranging 3-48 hrs; precipitating the copolymer formed with non solvent as herein described ;extracting the copolymer by known method.The copolymer is useful for light emitting diode applications .

Full Text	The present invention relates to a process for the preparation of novel alkyl-cycloalkyl thiophene copolymers useful for light emitting diode applications. Inorganic systems are conventionally used for light emitting diode applications. The methods of preparation associated with these systems are, however, very complicated and costly. Moreover, fluorescence is produced only upto the range of green radiation and it will be usually only monochromatic. The above shortcomings of the inorganic systems can be overcome by employing organic systems. Optical and photonic applications of π-conjugated polymers have recently been of much interest in the applications of microelectronics. To be potentially useful in electronic applications, polymer should either be a solution or a melt processable material with high environmental stability. Solubility of a polymer can be enhanced by substituting the appropriate side groups. Thiophene polymers and blends are predominantly used as semiconductors. They find their applications in constructing various rectifying junctions and polymer based light emitting diodes. These polymers also have potential use in panel displays. As reported by Abdou et al ( Synthetic. Metals. 52, 159 1992) and Roncali ( Journal, of Chemical Reviews, 92, 711, 1992), polyalkyl thiophenes, which not only exhibit the interesting properties of π-conjugated polymers, but also are easy to handle, have attracted considerable attention of the researchers. Bellettete et al (Macromolecules, 28, 8587, 1995), Pomerantz et al (Macromolecules, 28, 5706, 1995) and Roncali (Journal, of Chemical Reviews, 97, 173, 1997) have reported that the enhanced steric hindrance from side groups lead to decreasing planarity of the main chain and an increasing band gap, ensuring the potential use of the polymer in light emitting diodes. Several homopolymers like pure hexyl thiophene and cyclohexyl thiophene have been tried for light emitting diodes. The main limitation of this homopolymer system is that its efficiency level is very less and although it is possible to get fluorescence at blue radiation level, which is obviously an improvement over the conventional inorganic system, yet the radiation achieved is still only monochromatic. Berggners et al (Nature, 372, 444, 1994), Andersson et al (Macromolecules, 28, 7525, 1995) and Sandman (Trends in Polymer Science, 5, 71, 1997) blended different homopolymers physically to produce light emitting diodes with varied colour emittance.But the main drawback associated with these polymer blends is that the properties of the final products depend on the compatibility among the constituent homopolymers. Thus the efficiency of light emission of the light emitting diodes is affected depending on the nature of the polymer blend used. Attempts have therefore been made by researchers to improve the light emission properties of polythiophenes by synthesising copolymers, wherein properties of the constituent homopolymers are incorporated. Lowe and Holdcraft (Macromolecules, 28, 4608,1995) synthesised copolymers based on poly (3-(2-(methacryloyloxy)ethyl)thiophene), which was reported to find application in photoresists. Blohm et al (Macromolecules, 26, 2704 1993) and Danieli et al. (Journal of Chemical Society Communication, 1473, 1986) studied in detail the copolymeric systems like Poly (3,4-dibutoxy thiophene vinylene) and Poly (thienylene phyenylene) copolymers for differrent electronic applications. The main objective of the present invention is to provide a process for the preparation of novel alkyl-cycloalkyl thiophene copolymers useful for light emitting diode applications, which obviates the drawbacks stated above. Another objective of the present invention is to use alkyl thiophenes in light emitting diodes applications to get better efficiency and varied range of colour emittance for applications like panel displays. Still another objective of the present invention is to prepare copolymers having very high regularity with high bandgaps. Yet another objective of the present invention is to prepare polythiophene copolymers having high solubility with very good thin film forming characteristics. In the drawings accompanying this specification, Formula I represents alkyl thiophene, wherein R = any alkyl such as pentyl, hexyl, heptyl, octyl. Formula II represents cycloalkyl thiophene wherein RI = any cycloalkyl such as cyclopentyl, cyclohexyl, cycloheptyl, cycloctyl. Formula III represents alkyl-cycloalkyl thiophene copolymer, where n, X and Y are integers. Accordingly, the present invention provides a process for the preparation of novel alkyl-cycloalkyl thiophene copolymers useful for light emitting diode applications, which comprises copolymerising alkyl thiophene and cycloalkyl thiophene in a ratio ranging from 1:0.1 to 1:10 in an organic solvent such as herein described in inert atmosphere in the presence of an oxidising agent in the range of 1-5 moles per mole of monomer mixture at a temperature in the range of 0-30 C for a period ranging 3-48 hrs; precipitating the copolymer formed with non- solvent as herein described extracting the copolymer by known method. In an embodiment of the present invention the oxidising agent used is selected from ferric chloride, potassium persulphate. In another embodiment of the present invention the non-solvent used is selected from as methanol, acetone, water. In yet another embodiment of the present invention the organic solvent used is selected from chloroform, acetonitrile, propylene carbonate, dichloromethane. In still another embodiment of the present invention the oxidising agent used is in the range of 1-5 moles per mole of mixture. In still another embodiment of the present invention the organic solvent used is in the range of 5-12 lit. Per mole of the oxidising agent used for the copolymerization. In still another embodiment of the present invention, the composition of the copolymers can be varied by changing the feed ratio of the binary mixture of alkyl thiophene and cycloalkyl thiophene. Cycloalkyl thiophene and alkyl thiophene are the basic monomers,which are synthesised by cross coupling halothiophene with alkyl halide using nickel catalyst by a known method. Alkyl thiophene is copolymerised with cycloalkyl thiophene in a molar ratio ranging from 1:0.1 to 1:10 in presence of an oxidising agent dissolved in an organic solvent at a temperature in the range of 0°- 30°C over a period of 3-48 hrs in an inert atmosphere. The copolymer formed is precipitated by a non-solvent in a conventional way. This precipitate is dissolved in an organic solvent and made into films, which are extracted in a known way to remove excess oxidising agent. The novelty of the present invention lies in the choosing of the monomers and the method used for their copolymerisation to form a novel compound which may successfully be used in the fabrication of light emitting diode devices. This invention is described in detail in the following examples which are provided by way of illustration only and therefore should not be construed to limit the scope of the invention. Example-1 12g of magnesium was dried in nitrogen for ten minutes and cooled in icebath. 300 ml of dry diethyl ether was added to the metal. To the contents 60 g of cyclohexyl chloride was added over 1 hr. After stirring for 3 hrs, the contents were refluxed for 24 hrs in a water bath. The contents were cooled and Ig of nickel catalyst was added followed by 82 g of bromothiophene and then refluxed for 48 hrs. The contents were neutralised with dilute hydrochloric acid extracted with ether and the ether layer was evaporated to dryness. the liquid obtained was purified using silica gel and finally distilled in order to get pure monomer of cyclohexyl thiophene. Similarly, n-hexyl thiophene was synthesised by replacing cyclohexyl chloride with hexyl chloride. 6gms. of anhydrous ferric chloride and 30ml. of dry chloroform were taken in a round bottom flask fitted with a condenser, and a dropping funnel. A binary mixture containing 0.2ml. of hexyl thiophene and 0.3 ml of cyclohexyl thiophene, dissolved in 10 ml. of chloroform was taken in the funnel and the contents of the flask were kept in a thermostatic bath, maintained at 0°C./ Oxygen free nitrogen was bubbled through the solution throughout the reaction. The monomers were added drop by drop for 1 hr. and the contents were stirred for 24 hrs. The copolymer was precipitated with 1 lit. of methanol.The copolymer was extracted using a soxhlet apparatus with methanol and acetone. Example-2 12g of magnesium was dried in nitrogen for ten minutes and cooled in icebath. 300 ml of dry diethyl ether was added to the metal. To the contents 60 g of cyclohexyl chloride was added over 1 hr. After stirring for 3 hrs, the contents were refluxed for 24 hrs in a water bath. The contents were cooled and Ig of nickel catalyst was added followed by 82 g of bromothiophene and then refluxed for 48 hrs. The contents were neutralised with dil hydrochloric acid extracted with ether and the ether layer was evaporated to driness. the liquid obtained was purified using silica gel and finally distilled in order to get pure monomer of cyclohexyl thiophene. Similarly, n-hexyl thiophene was synthesised by replacing cyclohexyl chloride with hexyl chloride. 12 gms. of anhydrous ferric chloride and 60ml. of dry chloroform were taken in a round bottom flask fitted with a condenser, and a dropping runnel. A binary mixture containing O.lml. of hexyl thiophene and 0.9 ml of cyclohexyl thiophene, dissolved in 20 ml. of chloroform was taken in the funnel and the contents of the flask were kept in a thermostatic bath, maintained at 25oC. Oxygen free nitrogen was bubbled through the solution throughout the reaction. The monomers were added drop by drop for Ihr. and the contents were stirred for 48 hrs. The copolymer was precipitated with 3 lit. of methanol.The copolymer was extracted using a soxhlet apparatus with methanol and acetone. Example-3 12g of magnesium was dried in nitrogen for ten minutes and cooled in icebath. 300 ml of dry diethyl ether was added to the metal. To the contents 60 g of cyclohexyl chloride was added over for 1 hr. After stirring for 3 hrs, the contents were refluxed for 24 hrs in a water bath. The contents were cooled and Ig of nickel catalyst was added followed by 82 g of bromothiophene and then refluxed for 48 hrs. The contents were neutralised with dil hydrochloric acid extracted with ether and the ether layer was evaporated to driness. the liquid obtained was purified using silica gel and finally distilled in order to get pure monomer of cyclohexyl thiophene. Similarly, n-hexyl thiophene was synthesised by replacing cyclohexyl chloride with hexyl chloride. A binary mixture containing 0.5ml. of hexyl thiophene and 0.5 ml of cyclohexyl thiophene, dissolved in 20 ml. of chloroform was taken in a round bottom flask fitted with a condenser, and a dropping funnel and 9 gms. of anhydrous ferric chloride, dissolved in 50 ml. of dichloromethane were added drop by drop for 4 hrs. The contents of the flask were kept in a thermostatic bath, maintained at 25oC and the stirring was continued for 24hrs. The copolymer formed was regenerated with methanol. Finally the copolymer was extracted using a soxhlet apparatus with methanol and acetone. Example-4 12g of magnesium was dried in nitrogen for ten minutes and cooled in icebath. 300 ml of dry diethyl ether was added to the metal. To the contents 60 g of cyclohexyl chloride was added for 1 hr. After stirring for 3 hrs, the contents were refluxed for 24 hrs in a water bath. The contents were cooled and Ig of nickel catalyst was added followed by 82 g of bromothiophene and then refluxed for 48 hrs. The contents were neutralised with dil hydrochloric acid extracted with ether and the ether layer was evaporated to driness. the liquid obtained was purified using silica gel and finally distilled in order to get pure monomer of cyclohexyl thiophene. Similarly, n-hexyl thiophene was synthesised by replacing cyclohexyl chloride with hexyl chloride. A binary mixture containing 0.9ml. of hexyl thiophene and 0.1 ml of cyclohexyl thiophene, dissolved in 20 ml. of acetonitrile was taken in a round bottom flask fitted with a condenser, and a dropping funnel and 27 gms. of potassium persulphate, dissolved in 60ml. of acetonitrile were added drop by drop for 2 hrs. The contents of the flask were kept in a thermostatic bath, maintained at 25°C and the stirring was continued for 24hrs. The copolymer formed was regenerated with methanol. Finally the copolymer was extracted using a soxhlet apparatus with methanol and acetone. The main advantages of the present invention are the following. 1. Temperature management for this polymerisation is much easier, because it is not conducted at a very high temperature. 2. The copolymer of the present invention exhibits very high regularity with high bandgaps. 3. The copolymer of the present invention exhibits high solubility with very good thin film forming characteristics. 4. It shows high regioregularity and therefore high light emission efficiency. 5. The resulting copolymer of the present invention can be used as conducting polymer for Light emitting diode applications at low working voltage with higher efficiency of light emittance in various wavelengths. We Claim: 1. A process for the preparation of novel alkyl-cycloalkyl thiophene copolymers of formula III of the drawing accompanying the specification useful for light emitting diode applications, which comprises: i) copolymerising alkyl thiophene and cycloalkyl thiophene in a ratio ranging from 1:0.1 to 1:10 in an such as herein described inert atmosphere in the presence of an oxidising agent selected from ferric chloride and potassium persulphate in the range of 1-5 moles per mole of monomer mixture at a temperature in the range of 0-30° C for a period ranging 3-48 hrs; ii) precipitating the copolymer formed with non-solvent as herein described ; iii) extracting the copolymer by known method to obtain alkyl-cycloalkyl thiophene. 2. A process as claimed in claim 1, wherein the non-solvent used is selected from methanol, acetone and water. 3. A process as claimed in claim 1 , wherein the organic solvent used is selected from chloroform, acetonitrile, propylene carbonate and dichloromethane. 4. A process as claimed in claim 1 , wherein the organic solvent used is in the range of 5- 12 lit. per mole of the oxidising agent used for the copolymerization. 5. A process for the preparation of novel alkyl-cycloalkyl thiophene copolymers useful for light emitting diode applications, substantially as herein described with reference to the examples and drawings accompanying this specification.

Full Text

The present invention relates to a process for the preparation of novel alkyl-cycloalkyl thiophene copolymers useful for light emitting diode applications.
Inorganic systems are conventionally used for light emitting diode applications. The methods of preparation associated with these systems are, however, very complicated and costly. Moreover, fluorescence is produced only upto the range of green radiation and it will be usually only monochromatic.
The above shortcomings of the inorganic systems can be overcome by employing organic systems. Optical and photonic applications of π-conjugated polymers have recently been of much interest in the applications of microelectronics. To be potentially useful in electronic applications, polymer should either be a solution or a melt processable material with high environmental stability. Solubility of a polymer can be enhanced by substituting the appropriate side groups. Thiophene polymers and blends are predominantly used as semiconductors. They find their applications in constructing various rectifying junctions and polymer based light emitting diodes. These polymers also have potential use in panel displays.
As reported by Abdou et al ( Synthetic. Metals. 52, 159 1992) and Roncali ( Journal, of Chemical Reviews, 92, 711, 1992), polyalkyl thiophenes, which not only exhibit the interesting properties of π-conjugated polymers, but also are easy to handle, have attracted considerable attention of the researchers. Bellettete et al (Macromolecules, 28, 8587, 1995), Pomerantz et al (Macromolecules, 28, 5706, 1995) and Roncali (Journal, of Chemical Reviews, 97, 173, 1997) have reported that the enhanced steric

hindrance from side groups lead to decreasing planarity of the main chain and an increasing band gap, ensuring the potential use of the polymer in light emitting diodes. Several homopolymers like pure hexyl thiophene and cyclohexyl thiophene have been tried for light emitting diodes. The main limitation of this homopolymer system is that its efficiency level is very less and although it is possible to get fluorescence at blue radiation level, which is obviously an improvement over the conventional inorganic system, yet the radiation achieved is still only monochromatic.
Berggners et al (Nature, 372, 444, 1994), Andersson et al (Macromolecules, 28, 7525, 1995) and Sandman (Trends in Polymer Science, 5, 71, 1997) blended different homopolymers physically to produce light emitting diodes with varied colour emittance.But the main drawback associated with these polymer blends is that the properties of the final products depend on the compatibility among the constituent homopolymers. Thus the efficiency of light emission of the light emitting diodes is affected depending on the nature of the polymer blend used.
Attempts have therefore been made by researchers to improve the light emission properties of polythiophenes by synthesising copolymers, wherein properties of the constituent homopolymers are incorporated. Lowe and Holdcraft (Macromolecules, 28, 4608,1995) synthesised copolymers based on poly (3-(2-(methacryloyloxy)ethyl)thiophene), which was reported to find application in photoresists. Blohm et al (Macromolecules, 26, 2704 1993) and Danieli et al. (Journal of Chemical Society Communication, 1473, 1986) studied in detail the copolymeric

systems like Poly (3,4-dibutoxy thiophene vinylene) and Poly (thienylene phyenylene) copolymers for differrent electronic applications.
The main objective of the present invention is to provide a process for the
preparation of novel alkyl-cycloalkyl thiophene copolymers useful for light emitting
diode applications, which obviates the drawbacks stated above.
Another objective of the present invention is to use alkyl thiophenes in light emitting
diodes applications to get better efficiency and varied range of colour emittance for
applications like panel displays.
Still another objective of the present invention is to prepare copolymers having very
high regularity with high bandgaps.
Yet another objective of the present invention is to prepare polythiophene
copolymers having high solubility with very good thin film forming characteristics.
In the drawings accompanying this specification,
Formula I represents alkyl thiophene, wherein R = any alkyl such as pentyl, hexyl,
heptyl, octyl.
Formula II represents cycloalkyl thiophene wherein RI = any cycloalkyl such as
cyclopentyl, cyclohexyl, cycloheptyl, cycloctyl.
Formula III represents alkyl-cycloalkyl thiophene copolymer, where n, X and Y are
integers.

Accordingly, the present invention provides a process for the preparation of novel alkyl-cycloalkyl thiophene copolymers useful for light emitting diode applications, which comprises copolymerising alkyl thiophene and cycloalkyl thiophene in a ratio ranging from 1:0.1 to 1:10
in an organic solvent such as herein described in inert atmosphere in the presence of an oxidising agent in the range of 1-5 moles per mole of monomer mixture at a temperature in the range of 0-30 C for a period ranging 3-48 hrs; precipitating the copolymer formed with non- solvent as herein described extracting the copolymer by known method.
In an embodiment of the present invention the oxidising agent used is selected from ferric chloride, potassium persulphate.
In another embodiment of the present invention the non-solvent used is selected from as methanol, acetone, water.
In yet another embodiment of the present invention the organic solvent used is selected from chloroform, acetonitrile, propylene carbonate, dichloromethane.
In still another embodiment of the present invention the oxidising agent used is in the range of 1-5 moles per mole of mixture.
In still another embodiment of the present invention the organic solvent used is in the range of 5-12 lit. Per mole of the oxidising agent used for the copolymerization.

In still another embodiment of the present invention, the composition of the copolymers can be varied by changing the feed ratio of the binary mixture of alkyl thiophene and cycloalkyl thiophene.
Cycloalkyl thiophene and alkyl thiophene are the basic monomers,which are synthesised
by cross coupling halothiophene with alkyl halide using nickel catalyst by a known
method.
Alkyl thiophene is copolymerised with cycloalkyl thiophene in a molar ratio ranging
from 1:0.1 to 1:10 in presence of an oxidising agent dissolved in an organic solvent at
a temperature in the range of 0°- 30°C over a period of 3-48 hrs in an inert
atmosphere. The copolymer formed is precipitated by a non-solvent in a conventional
way. This precipitate is dissolved in an organic solvent and made into films, which are
extracted in a known way to remove excess oxidising agent.
The novelty of the present invention lies in the choosing of the monomers and the
method used for their copolymerisation to form a novel compound which may
successfully be used in the fabrication of light emitting diode devices.
This invention is described in detail in the following examples which are provided
by way of illustration only and therefore should not be construed to limit the
scope of the invention.
Example-1
12g of magnesium was dried in nitrogen for ten minutes and cooled in icebath. 300 ml of dry diethyl ether was added to the metal. To the contents 60 g of cyclohexyl

chloride was added over 1 hr. After stirring for 3 hrs, the contents were refluxed for 24 hrs in a water bath. The contents were cooled and Ig of nickel catalyst was added followed by 82 g of bromothiophene and then refluxed for 48 hrs. The contents were neutralised with dilute hydrochloric acid extracted with ether and the ether layer was evaporated to dryness. the liquid obtained was purified using silica gel and finally distilled in order to get pure monomer of cyclohexyl thiophene. Similarly, n-hexyl thiophene was synthesised by replacing cyclohexyl chloride with hexyl chloride. 6gms. of anhydrous ferric chloride and 30ml. of dry chloroform were taken in a round bottom flask fitted with a condenser, and a dropping funnel. A binary mixture containing 0.2ml. of hexyl thiophene and 0.3 ml of cyclohexyl thiophene, dissolved in 10 ml. of chloroform was taken in the funnel and the contents of the flask were kept in a thermostatic bath, maintained at 0°C./ Oxygen free nitrogen was bubbled through the solution throughout the reaction. The monomers were added drop by drop for 1 hr. and the contents were stirred for 24 hrs. The copolymer was precipitated with 1 lit. of methanol.The copolymer was extracted using a soxhlet apparatus with methanol and acetone. Example-2
12g of magnesium was dried in nitrogen for ten minutes and cooled in icebath. 300 ml of dry diethyl ether was added to the metal. To the contents 60 g of cyclohexyl chloride was added over 1 hr. After stirring for 3 hrs, the contents were refluxed for 24 hrs in a water bath. The contents were cooled and Ig of nickel catalyst was added followed by 82 g of bromothiophene and then refluxed for 48 hrs. The contents were

neutralised with dil hydrochloric acid extracted with ether and the ether layer was evaporated to driness. the liquid obtained was purified using silica gel and finally distilled in order to get pure monomer of cyclohexyl thiophene. Similarly, n-hexyl thiophene was synthesised by replacing cyclohexyl chloride with hexyl chloride. 12 gms. of anhydrous ferric chloride and 60ml. of dry chloroform were taken in a round bottom flask fitted with a condenser, and a dropping runnel. A binary mixture containing O.lml. of hexyl thiophene and 0.9 ml of cyclohexyl thiophene, dissolved in 20 ml. of chloroform was taken in the funnel and the contents of the flask were kept in a thermostatic bath, maintained at 25oC. Oxygen free nitrogen was bubbled through the solution throughout the reaction. The monomers were added drop by drop for Ihr. and the contents were stirred for 48 hrs. The copolymer was precipitated with 3 lit. of methanol.The copolymer was extracted using a soxhlet apparatus with methanol and acetone.
Example-3
12g of magnesium was dried in nitrogen for ten minutes and cooled in icebath. 300 ml of dry diethyl ether was added to the metal. To the contents 60 g of cyclohexyl chloride was added over for 1 hr. After stirring for 3 hrs, the contents were refluxed for 24 hrs in a water bath. The contents were cooled and Ig of nickel catalyst was added followed by 82 g of bromothiophene and then refluxed for 48 hrs. The contents were neutralised with dil hydrochloric acid extracted with ether and the ether layer was evaporated to driness. the liquid obtained was purified using silica gel and finally

distilled in order to get pure monomer of cyclohexyl thiophene. Similarly, n-hexyl thiophene was synthesised by replacing cyclohexyl chloride with hexyl chloride. A binary mixture containing 0.5ml. of hexyl thiophene and 0.5 ml of cyclohexyl thiophene, dissolved in 20 ml. of chloroform was taken in a round bottom flask fitted with a condenser, and a dropping funnel and 9 gms. of anhydrous ferric chloride, dissolved in 50 ml. of dichloromethane were added drop by drop for 4 hrs. The contents of the flask were kept in a thermostatic bath, maintained at 25oC and the stirring was continued for 24hrs. The copolymer formed was regenerated with methanol. Finally the copolymer was extracted using a soxhlet apparatus with methanol and acetone.
Example-4
12g of magnesium was dried in nitrogen for ten minutes and cooled in icebath. 300 ml of dry diethyl ether was added to the metal. To the contents 60 g of cyclohexyl chloride was added for 1 hr. After stirring for 3 hrs, the contents were refluxed for 24 hrs in a water bath. The contents were cooled and Ig of nickel catalyst was added followed by 82 g of bromothiophene and then refluxed for 48 hrs. The contents were neutralised with dil hydrochloric acid extracted with ether and the ether layer was evaporated to driness. the liquid obtained was purified using silica gel and finally distilled in order to get pure monomer of cyclohexyl thiophene. Similarly, n-hexyl thiophene was synthesised by replacing cyclohexyl chloride with hexyl chloride.

A binary mixture containing 0.9ml. of hexyl thiophene and 0.1 ml of cyclohexyl thiophene, dissolved in 20 ml. of acetonitrile was taken in a round bottom flask fitted with a condenser, and a dropping funnel and 27 gms. of potassium persulphate, dissolved in 60ml. of acetonitrile were added drop by drop for 2 hrs. The contents of the flask were kept in a thermostatic bath, maintained at 25°C and the stirring was continued for 24hrs. The copolymer formed was regenerated with methanol. Finally the copolymer was extracted using a soxhlet apparatus with methanol and acetone. The main advantages of the present invention are the following.
1. Temperature management for this polymerisation is much easier, because it is not
conducted at a very high temperature.
2. The copolymer of the present invention exhibits very high regularity with high
bandgaps.
3. The copolymer of the present invention exhibits high solubility with very good thin
film forming characteristics.
4. It shows high regioregularity and therefore high light emission efficiency.
5. The resulting copolymer of the present invention can be used as conducting
polymer for Light emitting diode applications at low working voltage with higher
efficiency of light emittance in various wavelengths.

We Claim:
1. A process for the preparation of novel alkyl-cycloalkyl thiophene copolymers of formula
III of the drawing accompanying the specification useful for light emitting diode
applications, which comprises:
i) copolymerising alkyl thiophene and cycloalkyl thiophene in a ratio ranging from 1:0.1 to 1:10 in an such as herein described inert atmosphere in the presence of an oxidising agent selected from ferric chloride and potassium persulphate in the range of 1-5 moles per mole of monomer mixture at a temperature in the range of 0-30° C for a period ranging 3-48 hrs;
ii) precipitating the copolymer formed with non-solvent as herein described ; iii) extracting the copolymer by known method to obtain alkyl-cycloalkyl thiophene.
2. A process as claimed in claim 1, wherein the non-solvent used is selected from methanol, acetone and water.
3. A process as claimed in claim 1 , wherein the organic solvent used is selected from
chloroform, acetonitrile, propylene carbonate and dichloromethane.
4. A process as claimed in claim 1 , wherein the organic solvent used is in the range of 5-
12 lit. per mole of the oxidising agent used for the copolymerization.
5. A process for the preparation of novel alkyl-cycloalkyl thiophene copolymers useful for
light emitting diode applications, substantially as herein described with reference to the
examples and drawings accompanying this specification.

Documents:

1310-del-1998-abstract.pdf

1310-del-1998-claims.pdf

1310-del-1998-correspondence-others.pdf

1310-del-1998-correspondence-po.pdf

1310-del-1998-description (complete).pdf

1310-del-1998-drawings.pdf

1310-del-1998-form-1.pdf

1310-del-1998-form-2.pdf

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Patent Number

215655

Indian Patent Application Number

1310/DEL/1998

PG Journal Number

12/2008

Publication Date

21-Mar-2008

Grant Date

29-Feb-2008

Date of Filing

15-May-1998

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	NARAYANASASTRI SOMANATHAN	CENTRAL LEATHER RESEARCH INSTITUTE, ADYAR, CHENAI - 600020,INDIA.
2	THIRUMALACHARI RAMASAMI	CENTRAL LEATHER RESEARCH INSTITUTE, ADYAR, CHENAI - 600020,INDIA.
3	VIBHA RANI	TATA INSTITUTE, OF FUNDAMENTAL RESEARCH, MUMBAI - 400005, INDIA.
4	RAJIV PRAKASH	TATA INSTITUTE, OF FUNDAMENTAL RESEARCH, MUMBAI - 400005, INDIA.
5	KALATHUR SABDHAM VENGEPURAM SRINIVASAN.

PCT International Classification Number

C08F 4/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA