Title of Invention	A NOVEL COPOLYAROMATIC AMINE, PROCESS OF PREPARATION THEREOF AND A COMPOSITE THEREFROM
Abstract	The present invention relates to the synthesis of copolymer of aniline with substituted anilines using Sodium 5-sulphoisophthalic acid (NaSIPA) as dopant, resulting in the formation of copolymer having thermal stability upto 285-300°C and enhanced solubility in organic solvents like Monoethylene glycol (MEG), Dimethyl sulphoxide (DMSO), Dimethly formamide (DMF), N-methyl pyrrolidone (NMP), Tetrahydro furan (THF). The electrical conductivity is in the same range as that of homopolymer of aniline (polyaniline). These copolymers can be used for the dissipation of electrostatic charge, for the shielding of electromagnetic interference and as absorbing of electromagnetic waves in the microwave region and for corrosion preventive studies. The copolymer is free from benzidine even at 300°C, which is the temperature required for blending with certain polymers. The invention also provides a method of preparation of melt blended conducting composites of said copolymers with thermoplastics like nylon, acrylics, polyamides, HIPS, PC, PPO+HIPS and a combination thereof. These melt blended composites have potential applications in the emerging areas of material science like electrostatic charge dissipation (ESD), Electromagnetic interference (EMI) shielding, stealth technology or microwave absorption and for anticorrosive coating formulations.

Title of Invention

A NOVEL COPOLYAROMATIC AMINE, PROCESS OF PREPARATION THEREOF AND A COMPOSITE THEREFROM

Abstract

The present invention relates to the synthesis of copolymer of aniline with substituted anilines using Sodium 5-sulphoisophthalic acid (NaSIPA) as dopant, resulting in the formation of copolymer having thermal stability upto 285-300°C and enhanced solubility in organic solvents like Monoethylene glycol (MEG), Dimethyl sulphoxide (DMSO), Dimethly formamide (DMF), N-methyl pyrrolidone (NMP), Tetrahydro furan (THF). The electrical conductivity is in the same range as that of homopolymer of aniline (polyaniline). These copolymers can be used for the dissipation of electrostatic charge, for the shielding of electromagnetic interference and as absorbing of electromagnetic waves in the microwave region and for corrosion preventive studies. The copolymer is free from benzidine even at 300°C, which is the temperature required for blending with certain polymers. The invention also provides a method of preparation of melt blended conducting composites of said copolymers with thermoplastics like nylon, acrylics, polyamides, HIPS, PC, PPO+HIPS and a combination thereof. These melt blended composites have potential applications in the emerging areas of material science like electrostatic charge dissipation (ESD), Electromagnetic interference (EMI) shielding, stealth technology or microwave absorption and for anticorrosive coating formulations.

Full Text	FIELD OF INVENTION The present invention relates to the synthesis of conducting copolymer of poly aromatic amines and substituted aromatic amines in the presence of specific organic dopants and a process for the preparation of the said copolymer. These copolymers can be used for the dissipation of electrostatic charge, for the shielding of electromagnetic interference and as absorbing of electromagnetic waves in the microwave region and for corrosion preventive studies. The invention also provides a method of preparation of melt blended conducting composites of said copolymers with thermoplastics like PET, nylon, acrylics, polyamides, high impact polystyrene (HIPS), polycarbonate (PC), polypropyleneoxide(PPO)+HIPS and a combination of thereof. These melt blended composites have applications in the emerging areas of material science like electrostatic charge dissipation (ESD), Electromagnetic interference (EMI) shielding, stealth technology or microwave absorption and for anticorrosive coating formulations. BACKGROUND OF INVENTION Conducting polymers have emerged as important class of electronic materials because of their potential and wide applications in energy storage systems, optoelectronic devices, light emitting diodes, sensors for hazardous gases and toxic fumes, corrosion inhibitors for iron and mild steel and EMI shielding in radio frequency range and microwave absorption. The conducting polymer is a subfield of the larger, older field old organic electrical conductors which had already started in early 1970's, with the discovery of (SN)x. These organic materials may possess electronic conductivity comparable to metals. The conducting polymer, polyacetylene, has electronic conductivity of the order of 105 S/cm whereas the conductivity of copper is 106 S/cm. However, with the idea that electronic conductivity can be varied with doping level (or oxidation state) has revolutionized the area of research. These acquire importance over inorganic semiconductors in their application because of their high strength to weight ratio, toughness, low cost and ease of processing into film. The prospect of plastic metals has inspired much interest in these materials for technological applications such as antistatic coatings and electromagnetic interference shielding and in other areas where light weight, flexibility and high conductivity materials are required. Among conducting polymers. polyaniline and its analogues have been widely studied due to its ease of protonic acid doping in the emeraldine form and its environmental stability in both doped and undoped forms. Conducting polymer, polyaniline, exists in various forms and each form find technological application. The fully reduced form of polyaniline is leucoemeraldine which finds applications in Li-polyaniline battery and electrochromic devices. 50 % reduced and 50 % oxidized form of polyaniline is termed as emeraldine base which is the insulating form of polyaniline. It finds application in sensors for HC1 gas and as corrosion protective coating on iron and mild steel. Doping of emeraldine form leads to the formation of conducting polyaniline which is used as an electrode material in batteries, sensors, EMI shielding and electrochromic devices. The fully oxidized form of polyaniline is pernigraniline which find applications in non-linear optics. Conductivity in polyaniline depends on the degree of protonation of the material as well as on the oxidation state of the chains. The polymerization of aromatic amines to poly aromatic amines in the presence of organic protonic acids like p-toluene sulphonic acid, dodecylbenzene sulphonic acid and aerosol OT may bring certain changes in the properties of polyaniline because conduction mechanism in polyaniline involves protonation as well as ingress of counter anions to maintain charge neutrality. Protonation and electron transfer in polyaniline leads to the formation of radical cations by an internal redox reaction which causes the reorganization of electronic structure to give two semiquinone radical cations. In the doping process, ingress of anions occurs to maintain charge neutrality in the resultant doped polyaniline matrix. This implies that nature of anions should influence the properties of the resulting polyaniline. This is the reason why polyaniline doped with inorganic dopants like Cf and SO42- are thermally less stable than the polyaniline doped with organic dopants like p-toluene sulphonate or dodecylbenzenesulphonate. The invention relates to the preparation of copolymer of aromatic amines which should be soluble in organic solvents like monoethylene glycol (MEG), THF, DMSO, DMF etc. which should be thermally stable upto 285-300°C. It was found that when the polymerization of aromatic amines was carried out in the presence of sodium salt of sulfo-isophthalic acid and the like, it has resulted in the preparation of polyaniline which is thermally stable upto 300°C but the polymer was insoluble in organic solvent like MEG which was a desired property for its application for blending with polyester etc. Polyaniline doped with conventional inorganic acids is thermally stable upto 140-150°C whereas polyaniline doped with p-toluene sulphonic acid, dodecyl benzene sulphonic acid is thermally stable upto 240-250°C. The polymerization carried out with NaSIPA, LiSIPA and the like resulted in the preparation of polymer which is thermally stable upto 300°C. Doping of polyaniline with organic protonic acids can be carried out by direct method in which a monomer is polymerized in the presence of organic protonic acid or by indirect method in which emeraldine base is doped with desired organic acid. Isothermal studies data of the Polyaniline doped with dodecylbenzene sulphonic acid (DBSA) shows that whereas in case of PANI-DBS system, at a isothermal temperature of 200°C, there is weight loss of-4.82 % which increases to 19.25 % at 250°C. This implies that PANI-DBSA system can be used for melt blending applications where the temperature of the insulating system does not exceed 200°C. In case of PANI-RIL system, isothermal studies indicated that upto 250°C, there is loss of -10.15 % from the PANI-RIL system. At temperatures of 280°C, the loss is -12.4582 % whereas the loss at 300°C is ~ 14%. This means that polymers can be melt blended with other polymeric systems having melting temperatures from 280-290°C. However, this polymer was insoluble in monoethylene glycol (MEG) which was a medium required for blending with specific polymer like PET. In order to achieve solubilization of polyaniline in organic solvents, synthesis of copolymers of substituted aniline with aniline were formed. The copolymers of these substituted anilines with aniline were carried out keeping the ratio of aniline: substituted aniline:: 95 : 5 or aniline: substituted aniline :: 90 : 10. These ratios were taken in order to see the effect of copolymerization on solubilization and that the copolymerization should not lead in decrease in conductivity compared to parent polymer, polyaromatic amine. DSC studies of the copolymer doped with NaSIPA showed initial transition at 100°C which may be due to the water entrapped in the polymer backbone. A small transition was also observed at 140°C which may be associated with some transition taken place in the dopant because the same transition has been observed in the DSC of the dopant molecule. After this, a sharp transition is observed at 290°C which is associated with the melting point of the dopant moiety because the same behavior is observed in the dopant molecule itself. The DSC and TGA studies have shown that these melt blended composites (PET + doped copolymer) have melting point around 252-254°C are thermally stable upto 445°C XRD studies of the base and doped forms of copolymers have been carried out. The incorporation of dopant brings some degree of crystallanity in the copolymer matrix because base forms of the copolymers show completely amorphous behavior. The conductivity of the copolymers prepared by taking 95:5 ratio of aniline: substituted aniline (2-isopropyl aniline or 2-sec-butylaniline), were determined using four-probe method. US Patent 5,980,784 reports a method for producing a soluble conductive polymer having acidic groups, which comprises subjecting to electrolytic polymerization (a) at least one compound selected from the group consisting of acidic group-substituted anilines, acidic group-substituted pyrroles, acidic group substituted thiophenes, acidic group-substituted furans, acidic group-substituted selenophenes, acidic group-substituted tellurophenes, acidic group-substituted isothianaphthenes, acidic group-substituted isobenzofurans, acidic group-substituted isoindolines, acidic group-substituted isobenzoselenophenes, acidic group-substituted isobenzotellurophenes, and their metal salts, ammonium salts and substituted ammonium salts in a solution containing (b) a basic compound. United States Patent 5,376,728 reports invention related to Amino-substituted polymers containing graft polymer segments derived from aromatic nitrogen-containing monomers. Preferred aromatic nitrogen-containing moieties are illustrated by aniline, and preferred low T.sub.g amino-substituted interpolymers comprise amino-substituted ethylene propylene norbornene elastomeric terpolymers. The polymers of this invention are useful in electrical, textile and other applications. United States Patent 6552107 reports a process for Melt or solution processable highly conducting polyaniline and process for preparation thereof, and blends thereof with PVC and EVA. A melt or solution processable polyaniline which comprises polyaniline doped or protonated with a dopant of the formula (1), (2) or (3) shown below said melt or solution processable polyaniline havinga conductivity ranging between 3 to 60 S/cm, (b) high solubility in weak polar or non polar solvents selected from chloroform, tetrahydrofuran, xylene, and m-cresol, thermal stability up to 200° C, (d) three dimensional variable range doping condition in the range of 150 to 50 K and a high degree of crystalline order. United States Patent 7,279,534: The present invention provides block copolymers containing at least one block of a poly(heteroaromatic) polymer and at least two blocks of a non-conjugated polymer. The poly(heteroaromatic) polymer is an intrinsically conducting polymer (ICP), and when in the oxidized form it is electrically conducting. When the ICP block or blocks of the block copolymer are in the doped form, the block copolymer is electrically conducting. Preferably the conducting block copolymers have conductivities in the range 10.sup.-6-10.sup.3 S/cm. Block copolymers of this invention are soluble or dispersible in water, one or more organic solvents, or in a mixture thereof at a level. Canadian Patents Database Patent Application: CA 2496406 (54) Methods for directly producing stable aqueous dispersions of electrically conducting polyanilines: Methods are provided for directly producing a stable aqueous dispersion of an electrically conducting polyaniline, comprising synthesizing an electrically conducting polyaniline in the presence of a polymeric acid in aqueous solution, thereby forming an as synthesized aqueous dispersion comprising the electrically conducting polyaniline and the polymeric acid, and contacting the as-synthesized aqueous dispersion with at least one ion exchange resin under conditions suitable to produce a stable aqueous dispersion of an electrically conducting polyaniline. Aqueous dispersions produced by the methods of the invention are useful for preparing buffer layers for use in electroluminescent (EL) devices. (WO/2006/026539) RESEAUX DE PERCOLATION SEMI-CONDUCTEURS: The present invention relates to a composition comprising carbon nanotubes in a semiconductive matrix. These compositions are useful in printing semiconducting portions of thin film transistors. Canadian Patents Database (12) Patent: CA 2167846 (54) Corrosion resistant metal laminates having, in series, a metal layer, a non-metal conductive layer and a nonconducting layer. The non-metal conductive layer comprises inherently conducting polymer, e.g. polyaniline or polypyrrole, in a non-conducting matrix, e.g. an inorganic matrix such as a silicate, a thermoplastic polymer matrix such as a polyolefin or a vinyl polymer or a thermoset polymer matrix such an epoxy, polyurethane or a polyimide. Preferred intrinsically conductive polymers include sulfonic acid doped polyaniline. The inherently conducting polymer-containing matrix is preferably strongly adhesive to metal and provides enhanced corrosion resistance to the metal in a variety of corrosive environments such as acidic, alkaline, and salt environments. US Patent Number: US7,160,575 Bl) issued January 9, 2007Measurement in the frequency range 3 MHz 106 Hz of the dielectric characteristics of emeraldine base polyaniline dissolved in l-methyl-2-pyrrolidinone (NMP) and cast into bulk free-standing polymer films shows features similar to those reported by others and which are a result of microphase separation into reduced and oxidized repeat units. However, upon confinement into the cylindrical pores, of average diameter 20 nm, of a porous membrane such features of microphase separations do not occur. The microphase separation observed in the bulk polymer is suppressed by strong pinning of the charge carriers due to interactions of the polymer with pore walls together with constrained chain packing and a non-uniform rate of evaporation of the NMP solvent from the pores. This enhances the bulk conductivity after doping by reducing the internal intra-chain disorder introduced by microphase separation. (WO/1995/034080) Processible electrically conducting polyaniline compositions and processes for the preparation thereof: The present invention relates to conducting polymers. In particular, it relates to fluid-phase processible, electrically conductive polyaniline compositions and to processes for the preparation thereof as well as to shaped articles, such as parts, containers, fibers, tapes, films, coatings and the like, produced from the present polyaniline compositions. The invention also concerns the use of the compositions and conductive articles. US Patent Specification No. 5,006,278 teaches the preparation of a conductive product by mixing a liquid, a doping agent and an undoped polyaniline. The liquid is removed by evaporation. PCX Patent Application WO 89/01 694 discloses a processible polyaniline doped with a sulfonic acid. Said polyaniline is useful in processing conducting polymer blends using polyethylene, polypropylene and polyamides as the matrix polymer. According to PCX Patent Specification WO 90/1 3601 a polymer mixture is prepared by mixing a suitable liquid with a mixture of polyaniline and a multi-sulfonic acid, used as a doping agent, whereafter the liquid is evaporated. According to said specification, the doping is generally carried out at a temperature of 20 to 25 °C, and it is disclosed that the doping can be carried out as a heterogeneous reaction, followed by dissolution of the mixture in a suitable solvent. The processing into a final shape is carried out in the presence of a solvent. PCX Patent Application WO 90/1 0297, EP Patent Application No. 152 632 and US Patent Specification No. 5,002,700 all disclose the use of dodecylbenzenesulfonic acid as a doping agent for polyaniline. PCX Patent Application WO 90/01 775 describes the use of multisulfonic acids as doping agents for polyaniline with the advantage of better thermal stability compared with other sulfonic acids. In the examples of said application, the doping of polyaniline has been carried out in a suspension of polyaniline and the sulfonic acid in an aqueous solution of formic acid. PCX Patent Application W093/24554 describes the use of dopant anion substituted with one or more polar group(s) which is preferably hydrogen bonded. PCX Patent Specification WO 93/24555 describes the use of several dopant anions simultaneously, the electrically conducting polymer preferably being in particle form. Electrochemical behaviour of polyaniline, poly(o-toluidine) and their copolymer in organic sulphonic acids, Materials Letters 58 (2004) 3816— 3822 The effect of organic sulphonic acid on electrochemical, optical and conductivity properties of polyaniline (PA), poly(o-toluidine) (POT) and their copolymer polyaniline-copoly(o-toluidine) (PA-POT) thin films has been investigated. The films were synthesized electrochemically individually and then combinedly as binary copolymerization under cyclic voltammetric conditions in aqueous solution of sulphuric acid, p-toluene sulphonic acid, sulphamic acid and sulphosalicylic acid at room temperature. Synthesis and characterization of soluble conducting poly(o-/m-toIuidine-co-o-nitroaniline), Synthetic Metals 145 (2004) 113-118. Copolymers of o-/m-toluidine with o-nitroaniline were chemically synthesized in various molar ratios of the comonomers by emulsion polymerization. Although o-nitroaniline does not homopolymerize, the copolymers of o-nitroaniline with o-/m-toluidine could readily be synthesized. The copolymers show comparatively higher conductivity, better solubility and higher thermal stability than the homopolymers, ortho- and meta-polytoluidines. Subtle differences in the properties between the copolymers of o- and m-toluidine with o-nitroaniline could be due to the variation in the monomers and the orientation along the copolymer chains. Synthesis and Characterization of Processable Polyaniline Doped with Novel Dopant NaSIPA, Journal of Applied Polymer Science, 108 (2008) 1437-1446. Aniline has been polymerized in the presence of a novel dopant sodio-5-sulfo isophthallic acid (NaSIPA), via the chemical oxidative polymerization route. The thermal stability and processability of polyaniline prepared by indirect method (PDl) have been improved significantly (290°C) as compared to polyaniline doped with conventional inorganic dopants like HC1 or H2S04, without much loss of electronic conductivity (5.07 S/cm in PDl). This suggests its use for melt blending with engineering thermoplastics. However, polyaniline prepared by direct method (PD2) can be melt-blended only with conventional thermoplastics like polyethylene, polypropylene, polystyrene, etc. Low-temperature studies reveal the 1-D variable range hopping as a conduction mechanism for direct polymer (PD2), with parameters To and σo as 4112 K and 15.1 S/cm, respectively. However, for indirectly doped polymer (PDl) Arrhenius-type model, having parameters j(Ep-Ec)\| and ΣC as 0.04 eV and 28.4 S/cm, respectively, it suited well. The coherence length as found from XRD data was around 28.8 nm for PDl and 25.2 nm for PD2. OBJECTIVE OF THE INVENTION: Objective of the present invention is to provide a novel copolyaromatic amine. Another objective is to provide a process of preparation of copolyaromatic amine. Further objective of present invention is to provide a copolymer having thermal stability upto 300°C. Further objective is to provide the polymer free from benzidine during polymerization or heating to 300°C and therefore free from the potent carcinogens. Further objective is to provide a copolymer having improved solubility compared to homopolymer of aniline (polyaniline) in the organic solvents like Monoethylene glycol (MEG), Dimethyl sulphoxide (DMSO), Dimethly formamide (DMF). N-methyl pyrrolidone (NMP), Tetrahydro furan (THF). Further objective is to provide a copolymer which is easy to melt blend with PET due to good solubility in MEG compared to polyaniline and can be used in the areas like EMI shieling, microwave absorption, antistatic applications and anticorrosive formulations. Still another objective is to provide a melt blended composite material with PET, using novel copolymer, wherein the composite has better thermal stability, electrical conductivity and thermal conductivity than PET. SUMMARY OF INVENTION: The present invention relates to the synthesis of copolymer of aniline with substituted anilines using Sodium 5-sulphoisophthalic acid (NaSIPA) as dopant, resulting in the formation of copolymer having thermal stability upto 285-300°C. As compared to the homopolymer of aniline (polyaniline), these copolymers show enhanced solubility in organic solvents like Monoethylene glycol (MEG), Dimethyl sulphoxide (DMSO), Dimethly formamide (DMF), N-methyl pyrrolidone (NMP), Tetrahydro furan (THF). The electrical conductivity is in the same range as that of homopolymer of aniline (polyaniline). These copolymers can be used for the dissipation of electrostatic charge, for the shielding of electromagnetic interference and as absorbing of electromagnetic waves in the microwave region and for corrosion preventive studies. The copolymer is free from benzidine even at 300°C, which is the temperature required for blending with certain polymers. These results have been confirmed by TG-Mass studies of the samples carried out at 300°C. The benzidine is a potent carcinogen and can exert harmful effects even in traces. Both these novelties are realized due to the inventive step of preparation of copolymer of aniline and substituted anilines (like 2- isopropylaniline, 2-sec-butyl aniline) and doping the resultant copolymer with sodium 5-sulphoisophthalic acid. The melt blending of the said copolymers with polyethylene terephthalate (PET) leads to melt blended composite having better thermal stability, electrical conductivity and thermal conductivity than matrix polymer (PET). The invention also provides a method of preparation of melt blended conducting composites of said copolymers with thermoplastics like nylon, acrylics, polyamides, HIPS, PC, PPO+HIPS and a combination thereof. These melt blended composites have potential applications in the emerging areas of material science like electrostatic charge dissipation (ESD), Electromagnetic interference (EMI) shielding, stealth technology or microwave absorption and for anticorrosive coating formulations BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS Fig. 1 represents TGA, DTG, SDTA and MS curve of copolymer sample (aniline:2-isopropyl aniline: :95:5) doped with NaSIPA. Thermogravimetric curve clearly shows the thermal stability of the copolymer upto 300°C. TG-Mass curve shows absence of benzidine even at 300°C. Fig. 2 represents the TGA of melt blended composite of NaSIPA doped copolymer (aniline:2-isopropyl aniline::95:5) with PET. The ratio of PET: copolymer was 99.8 : 0.2. TGA curve clearly shows that thermal stability of composite is 438 °C. Fig. 3 represents the cyclic mode DSC of film of melt blended composite of NaSIPA doped copolymer (aniline:2-isopropyl aniline::95:5) with PET. The ratio of PET: copolymer was 98.0 : 2.0. DSC curve clearly shows that melting point of composite is 250 °C. Fig. 4 represents the TGA of melt blended composite of NaSIPA doped copolymer (aniline:2-isopropyl aniline::95:5) with PET. The ratio of PET: copolymer was 98 : 2.0. TGA curve clearly shows that thermal stability of composite is 445 °C. Fig. 5 represents resistance of copolymer of aniline and 2-isopropyl aniline (95:5) doped with NaSIPA Fig. 6 represents resistance of copolymer of aniline and 2-sec. butyl aniline (95:5) doped with NaSIPA DETAILED DESCRIPTION Accordingly the present invention provides a novel copolyaromatic amine of general formula as given below: (Formula Removed) wnerein R IS selected rrom tne bulky alkyl group containing 3 to 4 carbon atoms, wherein 'X" is a counter ion selected from the group consisting of sodium 5-sulphoisophthalic acid (NaSIPA), lithium 5-sulphoisophthalic acid (LiSIPA), wherein 'a' and 'b' are mole fraction of aniline and 2-isopropyl aniline in the resultant copolymer, wherein values of 'a' and 'b' is less than 1, wherein the molecular weight of the said copolymer is ranging between 20,000 to 80,000 g/mol, wherein the copolymer is having the following attributes: (a) thermal stability upto 300°C, (b) electrical conductivity in the range of 5 S/cm to 10"2 S/cm, (c) free from benzidine during polymerization or heating to 300°C. (d) Soluble in the organic solvents like: (i) monoethylene glycol (MEG), (ii) dimethyl sulphoxide (DMSO), (iii) dimethly formamide (DMF), (iv) N-methyl pyrrolidone (NMP), (v) tetrahydro furan (THF) Accordingly the present invention provides a novel process for the preparation of copolyaromatic amines of the general formula (1) as claimed in claim 1, wherein the process steps comprises: (a) preparing aqueous solutions of aniline and substituted aniline in the distilled water, (b) mixing aqueous solutions of aniline and substituted aniline monomers in the presence of protonic acid, wherein pH is in the range of 0 to 3, at temperature in the range of-5.0°C to +5.0°C, (c) adding an aqueous solution of oxidant slowly drop by drop to the said mixture with continuous stirring and temperature maintained in the range of-5.0 to +5.0°C, (d) allowing the reaction mixture to polymerize for a time period in a range of 4-6 hours and under continuous stirring, (e) filtering the said reaction mixture after the completion of the copolymerization, (f) thoroughly washing the said mixture with doubly distilled water till the filtrate becomes colorless and neutral in pH, (g) neutralizing the washed copolymer with aqueous alkali and drying the copolymer at a temperature in a range of 50-60°C under vacuum, till constant weight, (h) doping the neutralized copolymer with aqueous solution of protonic acid, under continuous stirring for 2-4 hours and pH is maintained in the range of 0-3, (i) filtering the doped copolymer on completion of doping process, (j) thoroughly washing the doped copolymer with doubly distilled water till the filtrate becomes colorless and neutral in pH, (k) drying the doped copolymer at a temperature in a range of 50-60°C under vacuum, till constant weight. In an embodiment of the present invention wherein the doping of copolymer with dopant in step number (h) can also be carried out directly at the polymerization time. In another embodiment of the present invention wherein the substituted aniline may be selected from the group comprising of 2-isopropyl aniline, 2-sec-butyl aniline. In another embodiment of the present invention wherein a copolymer as claimed in claiml wherein the ratio aniline: substituted aniline is in the range of 95:5 to 50:50. In another embodiment of the present invention wherein the concentration of aqueous solution of monomer as in step (a) may be in range of 0.1 M to 2.0 M. In another embodiment of the present invention wherein wherein oxidant may be selected from a group comprising of ammonium persulphate, potassium persulphate, sodium persulphate, ferric chloride, ferric p-toluene sulphonate. In another embodiment of the present invention wherein concentration of aqueous solution of oxidant may be ranging between 0.1M to 2.0 M In another embodiment of the present invention wherein protonic acid may be selected from the group comprising of sodium 5-sulphoisophthallic acid (NaSIPA) or Lithium 5-sulphoisophthallic acid (LiSIPA). In another embodiment of the present invention wherein neutralization of washed copolymer may be carried out from aqueous basic solution selected from the group comprising of ammonium hydroxide, sodium hydroxide and potassium hydroxide. The prepared copolymer is useful for making melt blend composite wherein the said melt blend composite comprising a copolymer and a matrix polymer may be selected from the group comprising of PET, nylon, acrylics, polyamides, high impact polystyrene (HIPS), polycarbonate (PC), polypropyleoxide (PPO) + HIPS and a combination thereof, wherein amount of copolymer is ranging between 0.2-20.0 % by weight. In another embodiment of the present invention wherein a melt blended composite wherein the copolymer may be selected preferably from poly(aniline-co-2-isopropyl aniline) or poly(aniline-co-2-sec-bytyl aniline). In another embodiment of the present invention wherein a composite is having the following properties: (a) thermal stability upto 450°C, (b) free from benzidine on heating upto 300°C, (c) electrical conductivity ranging from 10"13 to 10"9 S/cm, (d) thermal conductivity ranging from 0.14 to 0.3 W/mK, (e) static decay time of less than 2.0 sec. Preparation of copolymers and melt blended composites The following examples are given to illustrate the process of the present invention and should not be construed to limit the scope of the present invention. Example 1 0.095 mole of aniline and 0.005 mole of o-isopropylaniline are taken in a double walled reaction vessel in which 1.0 N of hydrochloric acid is there and is kept at -2°C. The reaction mixture is stirred and drop wise aqueous solution of ammonium peroxydisulphate is added in two hours time. The reaction mixture is stirred for 6 hours, till a greenish precipitate of copolymer is obtained. The mixture is filtered and washed thoroughly with distilled water till the filtrate is colourless. The co polymer so obtained is treated with aqueous 0.1 M ammonia solution and stirred for 2 hours. The reaction mixture is again filtered and washed thoroughly with distilled water. The precipitate so obtained is vacuum dried at 55°C with constancy of temperature maintained to within +/- 1° C. The copolymer is then doped with 0.5 M Sodium 5-sulphoisophthalic acid, the copolymer is filtered and the green copolymer is dried at 60°C. The thermal stability of the copolymer so obtained is 285°C as carried out by Thermogravimetric analysis (TGA). Example 2 0.095 mole of aniline and 0.005 mole of o-isopropylaniline are taken in a double walled reaction vessel in which 0.5 N of Sodium 5-sulphoisophthalic acid (NaSIPA) is there and is kept at -2°C. The reaction mixture is stirred and drop wise aqueous solution of ammonium peroxydisulphate is added in two hours time. The reaction mixture is stirred for 6 hours, till a greenish precipitate of copolymer is obtained. The mixture is filtered and washed thoroughly with distilled water till the colour of the filtrate is colourless. The copolymer so obtained is vacuum dried at 60°C with constancy of temperature maintained to within +/- 1°C. Thermal stability of the copolymer is 230 °C as carried out by Thermogravimetric analysis (TGA) Example 3 0.090 mole of aniline and 0.010 mole of o-isopropylaniline are taken in a double walled reaction vessel in which 1.0 N of hydrochloric acid is there and is kept at -2°C. The reaction mixture is stirred and drop wise aqueous solution of ammonium peroxydisulphate is added in two hours time. The reaction mixture is stirred for 6 hours, till a greenish precipitate of copolymer is obtained. The mixture is filtered and washed thoroughly with distilled water till the colour of the filtrate is colourless. The co polymer so obtained is treated with aqueous 0.1 M ammonia solution and stirred for 2 hours. The reaction mixture is again filtered and washed thoroughly with distilled water. The precipitate so obtained is vacuum dried at 55°C with constancy of temperature maintained to within +/- 1° C. The copolymer is then doped with 0.5 M Sodium 5-sulphoisophthalic acid, the copolymer is filtered and the green copolymer is dried at 60°C. The thermal stability of the copolymer so obtained is 275°C as carried out by Thermogravimetric analysis (TGA). Example 4 0.095 mole of aniline and 0.005 mole of o-sec butylaniline are taken in a double walled reaction vessel in which 1.0 N of hydrochloric acid is there and is kept at -2°C. The reaction mixture is stirred and drop wise aqueous solution of ammonium peroxydisulphate is added in two hours time. The reaction mixture is stirred for 6 hours, till a greenish precipitate of copolymer is obtained. The mixture is filtered and washed thoroughly with distilled water till the colour of the filtrate is colourless. The co polymer so obtained is treated with aqueous 0.1 M ammonia solution and stirred for 2 hours. The reaction mixture is again filtered and washed thoroughly with distilled water. The precipitate so obtained is vacuum dried at 55°C with constancy of temperature maintained to within +/- 1° C. The copolymer is then doped with 0.5 M Sodium 5-sulphoisophthalic acid, the copolymer is filtered and the green copolymer is dried at 60°C. The thermal stability of the copolymer so obtained is 280°C as carried out by Thermogravimetric analysis (TGA). Example 5 The copolymer having the ratio of aniline : 2-isopropyl aniline as 95:5 was melt blended with PET resin in a twin screw extruder having L/D ratio of 35.0 and keeping the barrel temperature at 285°C. The ratio of PET: copolymer was 99.8 : 0.2. The torque was maintained at 40-50 Nm and screw speed was 120 rpm. The melt blended strands were drawn and cooled to solidify. The strands were then palletized online to the cylindrical shape granules. The granules were dried for the period of 4 hours at 110°C under dynamic vacuum. The resultant composite granules show electrical conductivity of 3.72xl0-11 S/cm. The composite is thermally stable upto 438 °C and has melting point of 251 °C as determined from TGA and DSC respectively. Example 6 The copolymer having the ratio of aniline: 2-isopropyl aniline as 95:5 was melt blended with PET resin in a twin screw extruder having L/D ratio of 35.0 and keeping the barrel temperature at 285°C. The ratio of PET: copolymer was 98.0 : 2.0. The torque was maintained at 40-50 Nm and screw speed was 120 rpm. The melt blended strands were drawn and cooled to solidify. The strands were then palletized online to the cylindrical shape granules. The granules were dried for the period of 4 hours 110°C under dynamic vacuum. The resultant composite granules show electrical conductivity of 3.26x10-10 S/cm. The composite is thermally stable upto 445 °C and has melting point of 255 °C as determined from TGA and DSC respectively. Example 7 The copolymer having the ratio of aniline: 2-sec-butyl aniline as 95:5 was melt blended with PET resin in a twin screw extruder having L/D ratio of 35.0 and keeping the barrel temperature at 285°C. The ratio of PET: copolymer was 98.0 : 2.0. The torque was maintained at 40-50 Nm and screw speed was 120 rpm. The melt blended strands were drawn and cooled to solidify. The strands were then palletized online to the cylindrical shape granules. The granules were dried for the period of 4 hours 110°C under dynamic vacuum. The resultant composite granules show electrical conductivity of 3.26xl0-10 S/cm. The composite is thermally stable upto 440 °C and has melting point of 252 °C as determined from TGA and DSC respectively. Example 8 A copolymer having the ratio of aniline: 2-isopropyl aniline as 95:5 was selected. The granules of melt blended composite having the ratio of PET: copolymer:: 98.0: 0.2, were processed in a single screw extruder having L/D ratio of 25.0 and compression ratio of 4:1 and keeping the barrel temperature at 295°C. The torque was maintained at 60-80 Nm and screw speed was 20 rpm. The extruded film show electrical conductivity of 2.62x10-11 S/cm. The composite film is thermally stable upto 435 °C and has melting point of 250 °C as determined from TGA and DSC respectively. The static decay time was less than 2 second as determined by static decay meter. Comparative Example 1 0.095 mole of aniline and 0.005 mole of 2-isopropylaniline are taken in a double walled reaction vessel in which 1.0 N of hydrochloric acid is there and is kept at -2°C. The reaction mixture is stirred and drop wise aqueous solution of ammonium peroxydisulphate is added in two hours time. The reaction mixture is stirred for 6 hours, till a greenish precipitate of copolymer is obtained. The mixture is filtered and washed thoroughly with distilled water till the colour of the filtrate is colourless. The co polymer so obtained is treated with aqueous 0.1 M ammonia solution and stirred for 2 hours. The reaction mixture is again filtered and washed thoroughly with distilled water. The precipitate so obtained is vacuum dried at 55°C with constancy of temperature maintained to within +/- 1° C. The copolymer is then doped with 0.5 M HC1, the copolymer is filtered and the green copolymer is dried at 60-80°C. The thermal stability of the copolymer was found to be 120°C Comparative Example 2 0.095 mole of aniline and 0.005 mole of 2-isopropylaniline are taken in a double walled reaction vessel in which 1.0 N of hydrochloric acid is there and is kept at -2°C. The reaction mixture is stirred and drop wise aqueous solution of ammonium peroxydisulphate is added in two hours time. The reaction mixture is stirred for 6 hours, till a greenish precipitate of copolymer is obtained. The mixture is filtered and washed thoroughly with distilled water till the colour of the filtrate is colourless. The co polymer so obtained is treated with aqueous 0.1 M ammonia solution and stirred for 2 hours. The reaction mixture is again filtered and washed thoroughly with distilled water. The precipitate so obtained is vacuum dried at 55°C with constancy of temperature maintained to within +/- 1° C. The copolymer is then doped with 0.5 M dodecylbenzene sulphonic acid, the copolymer is filtered and the green copolymer is dried at 60-80°C. The thermal stability of the copolymer was found to be 210°C to 220°C. Comparative Example 3 0.10 mole of aniline is taken in a double walled reaction vessel in which 1.0 N of hydrochloric acid is there and is kept at -2°C. The reaction mixture is stirred and drop wise aqueous solution of ammonium peroxydisulphate is added in two hours time. The reaction mixture is stirred for 6 hours, till a greenish precipitate of polymer is obtained. The mixture is filtered and washed thoroughly with distilled water till the colour of the filtrate is colourless. The co polymer so obtained is treated with aqueous 0.1 M ammonia solution and stirred for 2 hours. The reaction mixture is again filtered and washed thoroughly with distilled water. The precipitate so obtained is vacuum dried at 55°C with constancy of temperature maintained to within +/- 1° C. The polymer is then doped with 0.5 M dodecylbenzene sulphonic acid, the copolymer is filtered and the green copolymer is dried at 60-80°C. The thermal stability of the polymer was found to be 220°C to 230°C. Comparative Example 4 0.10 mole of aniline is taken in a double walled reaction vessel in which 1.0 N of hydrochloric acid is there and is kept at -2°C. The reaction mixture is stirred and drop wise aqueous solution of ammonium peroxydisulphate is added in two hours time. The reaction mixture is stirred for 6 hours, till a greenish precipitate of polymer is obtained. The mixture is filtered and washed thoroughly with distilled water till the filtrate becomes colorless. The co polymer so obtained is treated with aqueous 0.1 M ammonia solution and stirred for 2 hours. The reaction mixture is again filtered and washed thoroughly with distilled water. The precipitate so obtained is vacuum dried at 55°C with constancy of temperature maintained to within +/- 1°C. The polymer is then doped with 0.5 M Sodium 5-sulphoisophthalic acid (NaSIPA), the copolymer is filtered and the green copolymer is dried at 60-80°C. The thermal stability of the polymer was found to be 300°C. The solubility of the said copolymer in MEG was relatively low. Comparative Example 5 0.10 mole of aniline is taken in a double walled reaction vessel in which 0.5 N of Sodium 5-sulphoisophthalic acid (NaSIPA) is there and is kept at -2°C. The reaction mixture is stirred and drop wise aqueous solution of ammonium peroxydisulphate is added in two hours time. The reaction mixture is stirred for 6 hours, till a greenish precipitate of polymer is obtained. The mixture is filtered and washed thoroughly with distilled water till the filtrate becomes colorless. The polymer so obtained is vacuum dried at 55°C with constancy of temperature maintained to within +/- 1° C. The thermal stability of the polymer was found to be 210-220°C. The copolymer has good solubility in MEG. Comparative Example 7 The PET granules were processed in a single screw extruder having L/D ratio of 25.0 and compression ratio of 4:1 and keeping the barrel temperature at 295°C. The torque was maintained at 60-80 Nm and screw speed was 20 rpm. The extruded film show electrical conductivity of 7.6x10-13 S/cm. The thermal stability is 433 °C and has melting point of 250 °C as determined from TGA and DSC respectively. The static decay time was greater than 60 seconds. We claim: (1) A novel copolyaromatic amine of general formula as given below: (Formula Removed) wherein 'R' is selected from the bulky alkyl group containing 3 to 4 carbon atoms, wherein 'X" is a counter ion selected from the group consisting of sodium 5-sulphoisophthalic acid (NaSIPA), lithium 5-sulphoisophthalic acid (LiSIPA), wherein 'a' and 'b' are mole fraction of aniline and 2-isopropyl aniline in the resultant copolymer, wherein values of 'a' and 'b' is less than 1, wherein the molecular weight of the said copolymer is ranging between 20,000 to 80,000 g/mol, wherein the copolymer is having the following attributes: (b) thermal stability upto 300°C, (b) electrical conductivity in the range of 5 S/cm to 10~2 S/cm, (c) free from benzidine during polymerization or heating to 300°C, (d) Soluble in the organic solvents like: (i) monoethylene glycol (MEG), (ii) dimethyl sulphoxide (DMSO), (iii) dimethly formamide (DMF), (iv) N-methyl pyrrolidone (NMP), (v) tetrahydro furan (THF) (2) A process for the preparation of copolyaromatic amines of the general formula (1) as claimed in claim 1, wherein the process steps comprises: (a) preparing aqueous solutions of aniline and substituted aniline in the distilled water, (b) mixing aqueous solutions of aniline and substituted aniline monomers in the presence of protonic acid, wherein pH is in the range of 0 to 3, at temperature in the range of-5.0°C to +5.0°C, (c) adding an aqueous solution of oxidant slowly drop by drop to the said mixture with continuous stirring and temperature maintained in the range of-5.0 to +5.0°C, (d) allowing the reaction mixture to polymerize for a time period in a range of 4-6 hours and under continuous stirring, (e) filtering the said reaction mixture after the completion of the copolymerization, (f) thoroughly washing the said mixture with doubly distilled water till the filtrate becomes colorless and neutral in pH, (g) neutralizing the washed copolymer with aqueous alkali and drying the copolymer at a temperature in a range of 50-60°C under vacuum, till constant weight, (h) doping the neutralized copolymer with aqueous solution of protonic acid, under continuous stirring for 2-4 hours and pH is maintained in the range of 0-3, (i) filtering the doped copolymer on completion of doping process, (j) thoroughly washing the doped copolymer with doubly distilled water till the filtrate becomes colorless and neutral in pH, (k) drying the doped copolymer at a temperature in a range of 50-60°C under vacuum, till constant weight. (3) A process as claimed in claim (2) wherein the doping of copolymer with dopant in step number (h) can also be carried out directly at the polymerization time. (4) A process as claimed in claim (2) wherein the substituted aniline is selected from the group comprising of 2-isopropyl aniline, 2-sec-butyl aniline. (5) A copolymer as claimed in claim 1 wherein the ratio aniline: substituted aniline is in the range of 95:5 to 50:50. (6) A process as claimed in claim (2) wherein the concentration of aqueous solution of monomer as in step (a) is ranging between 0.1M to 2.0 M. (7) A process as claimed in claim 2 wherein oxidant is selected from a group comprising of ammonium persulphate, potassium persulphate, sodium persulphate, ferric chloride, ferric p-toluene sulphonate. (8) A process as claimed in claim 2 wherein wherein concentration of aqueous solution of oxidant is ranging between 0.1M to 2.0 M (9) A process as claimed in claim 2 wherein protonic acid is selected from the group comprising of sodium 5-sulphoisophthallic acid (NaSIPA) or Lithium 5-sulphoisophthallic acid (LiSIPA). (10) A process as claimed in claim 2 wherein neutralization of washed copolymer is carried out from aqueous basic solution selected from the group comprising of ammonium hydroxide, sodium hydroxide and potassium hydroxide. (11) A melt blended composite comprising a copolymer as in claim 1, and a matrix polymer is selected from the group comprising of PET, nylon, acrylics, polyamides, high impact polystyrene (HIPS), polycarbonate (PC), polypropyleoxide (PPO) + HIPS and a combination thereof, wherein amount of copolymer is ranging between 0.2-20.0 % by weight. (12) A melt blended composite as claimed in claim 11 wherein the copolymer is selected preferably from poly(aniline-co-2-isopropyl aniline) or poly(aniline-co- 2-sec-bytyl aniline). (13) A composite as claimed in claim 11 wherein a melt blended composite have the following properties: (a) thermal stability upto 450°C, (b) free from benzidine on heating upto 300°C, (c) electrical conductivity ranging from 10-13 to 10-9 S/cm, (d) thermal conductivity ranging from 0.14 to 0.3 W/mK, (e) static decay time of less than 2.0 sec. (14) A novel copolyaromatic amine, process of preparation thereof and a composite therefrom substantially as herein described with reference to the examples and drawings accompanying this specification.

Full Text

FIELD OF INVENTION
The present invention relates to the synthesis of conducting copolymer of poly aromatic amines and substituted aromatic amines in the presence of specific organic dopants and a process for the preparation of the said copolymer. These copolymers can be used for the dissipation of electrostatic charge, for the shielding of electromagnetic interference and as absorbing of electromagnetic waves in the microwave region and for corrosion preventive studies.
The invention also provides a method of preparation of melt blended conducting composites of said copolymers with thermoplastics like PET, nylon, acrylics, polyamides, high impact polystyrene (HIPS), polycarbonate (PC), polypropyleneoxide(PPO)+HIPS and a combination of thereof. These melt blended composites have applications in the emerging areas of material science like electrostatic charge dissipation (ESD), Electromagnetic interference (EMI) shielding, stealth technology or microwave absorption and for anticorrosive coating formulations. BACKGROUND OF INVENTION
Conducting polymers have emerged as important class of electronic materials because of their potential and wide applications in energy storage systems, optoelectronic devices, light emitting diodes, sensors for hazardous gases and toxic fumes, corrosion inhibitors for iron and mild steel and EMI shielding in radio frequency range and microwave absorption. The conducting polymer is a subfield of the larger, older field old organic electrical conductors which had already started in early 1970's, with the discovery of (SN)x. These organic materials may possess electronic conductivity comparable to metals. The conducting polymer, polyacetylene, has electronic conductivity of the order of 105 S/cm whereas the conductivity of copper is 106 S/cm. However, with the idea that electronic conductivity can be varied with doping level (or oxidation state) has revolutionized the area of research. These acquire importance over inorganic semiconductors in their application because of their high strength to weight ratio, toughness, low cost and ease of processing into film. The prospect of plastic metals has inspired much interest in these materials for technological applications such as antistatic coatings and electromagnetic interference shielding and in other areas where light weight, flexibility and high conductivity materials are required. Among conducting polymers.
polyaniline and its analogues have been widely studied due to its ease of protonic acid doping in the emeraldine form and its environmental stability in both doped and undoped forms. Conducting polymer, polyaniline, exists in various forms and each form find technological application. The fully reduced form of polyaniline is leucoemeraldine which finds applications in Li-polyaniline battery and electrochromic devices. 50 % reduced and 50 % oxidized form of polyaniline is termed as emeraldine base which is the insulating form of polyaniline. It finds application in sensors for HC1 gas and as corrosion protective coating on iron and mild steel. Doping of emeraldine form leads to the formation of conducting polyaniline which is used as an electrode material in batteries, sensors, EMI shielding and electrochromic devices. The fully oxidized form of polyaniline is pernigraniline which find applications in non-linear optics. Conductivity in polyaniline depends on the degree of protonation of the material as well as on the oxidation state of the chains.
The polymerization of aromatic amines to poly aromatic amines in the presence of organic protonic acids like p-toluene sulphonic acid, dodecylbenzene sulphonic acid and aerosol OT may bring certain changes in the properties of polyaniline because conduction mechanism in polyaniline involves protonation as well as ingress of counter anions to maintain charge neutrality. Protonation and electron transfer in polyaniline leads to the formation of radical cations by an internal redox reaction which causes the reorganization of electronic structure to give two semiquinone radical cations. In the doping process, ingress of anions occurs to maintain charge neutrality in the resultant doped polyaniline matrix. This implies that nature of anions should influence the properties of the resulting polyaniline. This is the reason why polyaniline doped with inorganic dopants like Cf and SO42- are thermally less stable than the polyaniline doped with organic dopants like p-toluene sulphonate or dodecylbenzenesulphonate.
The invention relates to the preparation of copolymer of aromatic amines which should be soluble in organic solvents like monoethylene glycol (MEG), THF, DMSO, DMF etc. which should be thermally stable upto 285-300°C. It was found that when the polymerization of aromatic amines was carried out in the presence of sodium salt of sulfo-isophthalic acid and the like, it has resulted in the preparation of polyaniline which is thermally stable upto 300°C but the polymer was insoluble in organic solvent like
MEG which was a desired property for its application for blending with polyester etc. Polyaniline doped with conventional inorganic acids is thermally stable upto 140-150°C whereas polyaniline doped with p-toluene sulphonic acid, dodecyl benzene sulphonic acid is thermally stable upto 240-250°C. The polymerization carried out with NaSIPA, LiSIPA and the like resulted in the preparation of polymer which is thermally stable upto 300°C. Doping of polyaniline with organic protonic acids can be carried out by direct method in which a monomer is polymerized in the presence of organic protonic acid or by indirect method in which emeraldine base is doped with desired organic acid. Isothermal studies data of the Polyaniline doped with dodecylbenzene sulphonic acid (DBSA) shows that whereas in case of PANI-DBS system, at a isothermal temperature of 200°C, there is weight loss of-4.82 % which increases to 19.25 % at 250°C. This implies that PANI-DBSA system can be used for melt blending applications where the temperature of the insulating system does not exceed 200°C. In case of PANI-RIL system, isothermal studies indicated that upto 250°C, there is loss of -10.15 % from the PANI-RIL system. At temperatures of 280°C, the loss is -12.4582 % whereas the loss at 300°C is ~ 14%. This means that polymers can be melt blended with other polymeric systems having melting temperatures from 280-290°C. However, this polymer was insoluble in monoethylene glycol (MEG) which was a medium required for blending with specific polymer like PET.
In order to achieve solubilization of polyaniline in organic solvents, synthesis of copolymers of substituted aniline with aniline were formed. The copolymers of these substituted anilines with aniline were carried out keeping the ratio of aniline: substituted aniline:: 95 : 5 or aniline: substituted aniline :: 90 : 10. These ratios were taken in order to see the effect of copolymerization on solubilization and that the copolymerization should not lead in decrease in conductivity compared to parent polymer, polyaromatic amine. DSC studies of the copolymer doped with NaSIPA showed initial transition at 100°C which may be due to the water entrapped in the polymer backbone. A small transition was also observed at 140°C which may be associated with some transition taken place in the dopant because the same transition has been observed in the DSC of the dopant molecule. After this, a sharp transition is observed at 290°C which is associated with the
melting point of the dopant moiety because the same behavior is observed in the dopant
molecule itself.
The DSC and TGA studies have shown that these melt blended composites (PET + doped
copolymer) have melting point around 252-254°C are thermally stable upto 445°C
XRD studies of the base and doped forms of copolymers have been carried out. The
incorporation of dopant brings some degree of crystallanity in the copolymer matrix
because base forms of the copolymers show completely amorphous behavior.
The conductivity of the copolymers prepared by taking 95:5 ratio of aniline: substituted
aniline (2-isopropyl aniline or 2-sec-butylaniline), were determined using four-probe
method.
US Patent 5,980,784 reports a method for producing a soluble conductive polymer
having acidic groups, which comprises subjecting to electrolytic polymerization (a) at
least one compound selected from the group consisting of acidic group-substituted
anilines, acidic group-substituted pyrroles, acidic group substituted thiophenes, acidic
group-substituted furans, acidic group-substituted selenophenes, acidic group-substituted
tellurophenes, acidic group-substituted isothianaphthenes, acidic group-substituted
isobenzofurans, acidic group-substituted isoindolines, acidic group-substituted
isobenzoselenophenes, acidic group-substituted isobenzotellurophenes, and their metal
salts, ammonium salts and substituted ammonium salts in a solution containing (b) a
basic compound.
United States Patent 5,376,728 reports invention related to Amino-substituted polymers
containing graft polymer segments derived from aromatic nitrogen-containing monomers.
Preferred aromatic nitrogen-containing moieties are illustrated by aniline, and preferred
low T.sub.g amino-substituted interpolymers comprise amino-substituted ethylene
propylene norbornene elastomeric terpolymers. The polymers of this invention are useful
in electrical, textile and other applications.
United States Patent 6552107 reports a process for Melt or solution processable highly
conducting polyaniline and process for preparation thereof, and blends thereof with PVC
and EVA. A melt or solution processable polyaniline which comprises polyaniline doped
or protonated with a dopant of the formula (1), (2) or (3) shown below said melt or
solution processable polyaniline havinga conductivity ranging between 3 to 60 S/cm, (b)
high solubility in weak polar or non polar solvents selected from chloroform, tetrahydrofuran, xylene, and m-cresol, thermal stability up to 200° C, (d) three dimensional variable range doping condition in the range of 150 to 50 K and a high degree of crystalline order.
United States Patent 7,279,534: The present invention provides block copolymers containing at least one block of a poly(heteroaromatic) polymer and at least two blocks of a non-conjugated polymer. The poly(heteroaromatic) polymer is an intrinsically conducting polymer (ICP), and when in the oxidized form it is electrically conducting. When the ICP block or blocks of the block copolymer are in the doped form, the block copolymer is electrically conducting. Preferably the conducting block copolymers have conductivities in the range 10.sup.-6-10.sup.3 S/cm. Block copolymers of this invention are soluble or dispersible in water, one or more organic solvents, or in a mixture thereof at a level.
Canadian Patents Database Patent Application: CA 2496406 (54) Methods for directly producing stable aqueous dispersions of electrically conducting polyanilines: Methods are provided for directly producing a stable aqueous dispersion of an electrically conducting polyaniline, comprising synthesizing an electrically conducting polyaniline in the presence of a polymeric acid in aqueous solution, thereby forming an as synthesized aqueous dispersion comprising the electrically conducting polyaniline and the polymeric acid, and contacting the as-synthesized aqueous dispersion with at least one ion exchange resin under conditions suitable to produce a stable aqueous dispersion of an electrically conducting polyaniline. Aqueous dispersions produced by the methods of the invention are useful for preparing buffer layers for use in electroluminescent (EL) devices.
(WO/2006/026539) RESEAUX DE PERCOLATION SEMI-CONDUCTEURS: The present invention relates to a composition comprising carbon nanotubes in a semiconductive matrix. These compositions are useful in printing semiconducting portions of thin film transistors.
Canadian Patents Database (12) Patent: CA 2167846 (54) Corrosion resistant metal laminates having, in series, a metal layer, a non-metal conductive layer and a nonconducting layer. The non-metal conductive layer comprises inherently conducting
polymer, e.g. polyaniline or polypyrrole, in a non-conducting matrix, e.g. an inorganic matrix such as a silicate, a thermoplastic polymer matrix such as a polyolefin or a vinyl polymer or a thermoset polymer matrix such an epoxy, polyurethane or a polyimide. Preferred intrinsically conductive polymers include sulfonic acid doped polyaniline. The inherently conducting polymer-containing matrix is preferably strongly adhesive to metal and provides enhanced corrosion resistance to the metal in a variety of corrosive environments such as acidic, alkaline, and salt environments.
US Patent Number: US7,160,575 Bl) issued January 9, 2007Measurement in the frequency range 3 MHz 106 Hz of the dielectric characteristics of emeraldine base polyaniline dissolved in l-methyl-2-pyrrolidinone (NMP) and cast into bulk free-standing polymer films shows features similar to those reported by others and which are a result of microphase separation into reduced and oxidized repeat units. However, upon confinement into the cylindrical pores, of average diameter 20 nm, of a porous membrane such features of microphase separations do not occur. The microphase separation observed in the bulk polymer is suppressed by strong pinning of the charge carriers due to interactions of the polymer with pore walls together with constrained chain packing and a non-uniform rate of evaporation of the NMP solvent from the pores. This enhances the bulk conductivity after doping by reducing the internal intra-chain disorder introduced by microphase separation.
(WO/1995/034080) Processible electrically conducting polyaniline compositions and processes for the preparation thereof: The present invention relates to conducting polymers. In particular, it relates to fluid-phase processible, electrically conductive polyaniline compositions and to processes for the preparation thereof as well as to shaped articles, such as parts, containers, fibers, tapes, films, coatings and the like, produced from the present polyaniline compositions. The invention also concerns the use of the compositions and conductive articles.
US Patent Specification No. 5,006,278 teaches the preparation of a conductive product by mixing a liquid, a doping agent and an undoped polyaniline. The liquid is removed by evaporation.
PCX Patent Application WO 89/01 694 discloses a processible polyaniline doped with a sulfonic acid. Said polyaniline is useful in processing conducting polymer blends using polyethylene, polypropylene and polyamides as the matrix polymer.
According to PCX Patent Specification WO 90/1 3601 a polymer mixture is prepared by mixing a suitable liquid with a mixture of polyaniline and a multi-sulfonic acid, used as a doping agent, whereafter the liquid is evaporated. According to said specification, the doping is generally carried out at a temperature of 20 to 25 °C, and it is disclosed that the doping can be carried out as a heterogeneous reaction, followed by dissolution of the mixture in a suitable solvent. The processing into a final shape is carried out in the presence of a solvent.
PCX Patent Application WO 90/1 0297, EP Patent Application No. 152 632 and US Patent Specification No. 5,002,700 all disclose the use of dodecylbenzenesulfonic acid as a doping agent for polyaniline.
PCX Patent Application WO 90/01 775 describes the use of multisulfonic acids as doping agents for polyaniline with the advantage of better thermal stability compared with other sulfonic acids. In the examples of said application, the doping of polyaniline has been carried out in a suspension of polyaniline and the sulfonic acid in an aqueous solution of formic acid.
PCX Patent Application W093/24554 describes the use of dopant anion substituted with one or more polar group(s) which is preferably hydrogen bonded. PCX Patent Specification WO 93/24555 describes the use of several dopant anions simultaneously, the electrically conducting polymer preferably being in particle form. Electrochemical behaviour of polyaniline, poly(o-toluidine) and their copolymer in organic sulphonic acids, Materials Letters 58 (2004) 3816— 3822 The effect of organic sulphonic acid on electrochemical, optical and conductivity properties of polyaniline (PA), poly(o-toluidine) (POT) and their copolymer polyaniline-copoly(o-toluidine) (PA-POT) thin films has been investigated. The films were synthesized electrochemically individually and then combinedly as binary copolymerization under cyclic voltammetric conditions in aqueous solution of sulphuric acid, p-toluene sulphonic acid, sulphamic acid and sulphosalicylic acid at room temperature.
Synthesis and characterization of soluble conducting poly(o-/m-toIuidine-co-o-nitroaniline), Synthetic Metals 145 (2004) 113-118. Copolymers of o-/m-toluidine with o-nitroaniline were chemically synthesized in various molar ratios of the comonomers by emulsion polymerization. Although o-nitroaniline does not homopolymerize, the copolymers of o-nitroaniline with o-/m-toluidine could readily be synthesized. The copolymers show comparatively higher conductivity, better solubility and higher thermal stability than the homopolymers, ortho- and meta-polytoluidines. Subtle differences in the properties between the copolymers of o- and m-toluidine with o-nitroaniline could be due to the variation in the monomers and the orientation along the copolymer chains. Synthesis and Characterization of Processable Polyaniline Doped with Novel Dopant NaSIPA, Journal of Applied Polymer Science, 108 (2008) 1437-1446. Aniline has been polymerized in the presence of a novel dopant sodio-5-sulfo isophthallic acid (NaSIPA), via the chemical oxidative polymerization route. The thermal stability and processability of polyaniline prepared by indirect method (PDl) have been improved significantly (290°C) as compared to polyaniline doped with conventional inorganic dopants like HC1 or H2S04, without much loss of electronic conductivity (5.07 S/cm in PDl). This suggests its use for melt blending with engineering thermoplastics. However, polyaniline prepared by direct method (PD2) can be melt-blended only with conventional thermoplastics like polyethylene, polypropylene, polystyrene, etc. Low-temperature studies reveal the 1-D variable range hopping as a conduction mechanism for direct polymer (PD2), with parameters To and σo as 4112 K and 15.1 S/cm, respectively. However, for indirectly doped polymer (PDl) Arrhenius-type model, having parameters j(Ep-Ec)| and ΣC as 0.04 eV and 28.4 S/cm, respectively, it suited well. The coherence length as found from XRD data was around 28.8 nm for PDl and 25.2 nm for PD2.
OBJECTIVE OF THE INVENTION:
Objective of the present invention is to provide a novel copolyaromatic amine. Another objective is to provide a process of preparation of copolyaromatic amine. Further objective of present invention is to provide a copolymer having thermal stability upto 300°C.
Further objective is to provide the polymer free from benzidine during polymerization or heating to 300°C and therefore free from the potent carcinogens.
Further objective is to provide a copolymer having improved solubility compared to homopolymer of aniline (polyaniline) in the organic solvents like Monoethylene glycol (MEG), Dimethyl sulphoxide (DMSO), Dimethly formamide (DMF). N-methyl pyrrolidone (NMP), Tetrahydro furan (THF).
Further objective is to provide a copolymer which is easy to melt blend with PET due to good solubility in MEG compared to polyaniline and can be used in the areas like EMI shieling, microwave absorption, antistatic applications and anticorrosive formulations. Still another objective is to provide a melt blended composite material with PET, using novel copolymer, wherein the composite has better thermal stability, electrical conductivity and thermal conductivity than PET.
SUMMARY OF INVENTION:
The present invention relates to the synthesis of copolymer of aniline with substituted anilines using Sodium 5-sulphoisophthalic acid (NaSIPA) as dopant, resulting in the formation of copolymer having thermal stability upto 285-300°C. As compared to the homopolymer of aniline (polyaniline), these copolymers show enhanced solubility in organic solvents like Monoethylene glycol (MEG), Dimethyl sulphoxide (DMSO), Dimethly formamide (DMF), N-methyl pyrrolidone (NMP), Tetrahydro furan (THF). The electrical conductivity is in the same range as that of homopolymer of aniline (polyaniline). These copolymers can be used for the dissipation of electrostatic charge, for the shielding of electromagnetic interference and as absorbing of electromagnetic waves in the microwave region and for corrosion preventive studies.
The copolymer is free from benzidine even at 300°C, which is the temperature required for blending with certain polymers. These results have been confirmed by TG-Mass studies of the samples carried out at 300°C. The benzidine is a potent carcinogen and can exert harmful effects even in traces. Both these novelties are realized due to the inventive step of preparation of copolymer of aniline and substituted anilines (like 2-
isopropylaniline, 2-sec-butyl aniline) and doping the resultant copolymer with sodium 5-sulphoisophthalic acid.
The melt blending of the said copolymers with polyethylene terephthalate (PET) leads to melt blended composite having better thermal stability, electrical conductivity and thermal conductivity than matrix polymer (PET). The invention also provides a method of preparation of melt blended conducting composites of said copolymers with thermoplastics like nylon, acrylics, polyamides, HIPS, PC, PPO+HIPS and a combination thereof. These melt blended composites have potential applications in the emerging areas of material science like electrostatic charge dissipation (ESD), Electromagnetic interference (EMI) shielding, stealth technology or microwave absorption and for anticorrosive coating formulations
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig. 1 represents TGA, DTG, SDTA and MS curve of copolymer sample (aniline:2-isopropyl aniline: :95:5) doped with NaSIPA. Thermogravimetric curve clearly shows the thermal stability of the copolymer upto 300°C. TG-Mass curve shows absence of benzidine even at 300°C.
Fig. 2 represents the TGA of melt blended composite of NaSIPA doped copolymer (aniline:2-isopropyl aniline::95:5) with PET. The ratio of PET: copolymer was 99.8 : 0.2. TGA curve clearly shows that thermal stability of composite is 438 °C.
Fig. 3 represents the cyclic mode DSC of film of melt blended composite of NaSIPA doped copolymer (aniline:2-isopropyl aniline::95:5) with PET. The ratio of PET: copolymer was 98.0 : 2.0. DSC curve clearly shows that melting point of composite is
250 °C.
Fig. 4 represents the TGA of melt blended composite of NaSIPA doped copolymer (aniline:2-isopropyl aniline::95:5) with PET. The ratio of PET: copolymer was 98 : 2.0. TGA curve clearly shows that thermal stability of composite is 445 °C.
Fig. 5 represents resistance of copolymer of aniline and 2-isopropyl aniline (95:5) doped with NaSIPA
Fig. 6 represents resistance of copolymer of aniline and 2-sec. butyl aniline (95:5) doped with NaSIPA
DETAILED DESCRIPTION
Accordingly the present invention provides a novel copolyaromatic amine of general formula as given below:
(Formula Removed)
wnerein R IS selected rrom tne bulky alkyl group containing 3 to 4 carbon atoms,
wherein 'X" is a counter ion selected from the group consisting of sodium 5-sulphoisophthalic acid (NaSIPA), lithium 5-sulphoisophthalic acid (LiSIPA), wherein 'a' and 'b' are mole fraction of aniline and 2-isopropyl aniline in the resultant copolymer, wherein values of 'a' and 'b' is less than 1, wherein the molecular weight of the said copolymer is ranging between 20,000 to 80,000 g/mol, wherein the copolymer is having the following attributes:
(a) thermal stability upto 300°C, (b) electrical conductivity in the range of 5 S/cm to 10"2 S/cm, (c) free from benzidine during polymerization or heating to 300°C. (d) Soluble in the organic solvents like:
(i) monoethylene glycol (MEG), (ii) dimethyl sulphoxide (DMSO), (iii) dimethly formamide (DMF), (iv) N-methyl pyrrolidone (NMP), (v) tetrahydro furan (THF) Accordingly the present invention provides a novel process for the preparation of copolyaromatic amines of the general formula (1) as claimed in claim 1, wherein the process steps comprises:
(a) preparing aqueous solutions of aniline and substituted aniline in the distilled water, (b) mixing aqueous solutions of aniline and substituted aniline monomers in the presence of protonic acid, wherein pH is in the range of 0 to 3, at temperature in
the range of-5.0°C to +5.0°C, (c) adding an aqueous solution of oxidant slowly drop by drop to the said mixture with continuous stirring and temperature maintained in the range of-5.0 to +5.0°C, (d) allowing the reaction mixture to polymerize for a time period in a range of 4-6 hours and under continuous stirring, (e) filtering the said reaction mixture after the completion of the copolymerization, (f) thoroughly washing the said mixture with doubly distilled water till the filtrate becomes colorless and neutral in pH, (g) neutralizing the washed copolymer with aqueous alkali and drying the copolymer at a temperature in a range of 50-60°C under vacuum, till constant weight, (h) doping the neutralized copolymer with aqueous solution of protonic acid, under continuous stirring for 2-4 hours and pH is maintained in the range of 0-3, (i) filtering the doped copolymer on completion of doping process, (j) thoroughly washing the doped copolymer with doubly distilled water till the filtrate becomes colorless and neutral in pH, (k) drying the doped copolymer at a temperature in a range of 50-60°C under vacuum, till constant weight. In an embodiment of the present invention wherein the doping of copolymer with dopant in step number (h) can also be carried out directly at the polymerization time. In another embodiment of the present invention wherein the substituted aniline may be selected from the group comprising of 2-isopropyl aniline, 2-sec-butyl aniline. In another embodiment of the present invention wherein a copolymer as claimed in claiml wherein the ratio aniline: substituted aniline is in the range of 95:5 to 50:50. In another embodiment of the present invention wherein the concentration of aqueous solution of monomer as in step (a) may be in range of 0.1 M to 2.0 M. In another embodiment of the present invention wherein wherein oxidant may be selected from a group comprising of ammonium persulphate, potassium persulphate, sodium persulphate, ferric chloride, ferric p-toluene sulphonate.
In another embodiment of the present invention wherein concentration of aqueous solution of oxidant may be ranging between 0.1M to 2.0 M
In another embodiment of the present invention wherein protonic acid may be selected from the group comprising of sodium 5-sulphoisophthallic acid (NaSIPA) or Lithium 5-sulphoisophthallic acid (LiSIPA).
In another embodiment of the present invention wherein neutralization of washed copolymer may be carried out from aqueous basic solution selected from the group comprising of ammonium hydroxide, sodium hydroxide and potassium hydroxide. The prepared copolymer is useful for making melt blend composite wherein the said melt blend composite comprising a copolymer and a matrix polymer may be selected from the group comprising of PET, nylon, acrylics, polyamides, high impact polystyrene (HIPS), polycarbonate (PC), polypropyleoxide (PPO) + HIPS and a combination thereof, wherein amount of copolymer is ranging between 0.2-20.0 % by weight. In another embodiment of the present invention wherein a melt blended composite wherein the copolymer may be selected preferably from poly(aniline-co-2-isopropyl aniline) or poly(aniline-co-2-sec-bytyl aniline).
In another embodiment of the present invention wherein a composite is having the following properties:
(a) thermal stability upto 450°C, (b) free from benzidine on heating upto 300°C, (c) electrical conductivity ranging from 10"13 to 10"9 S/cm, (d) thermal conductivity ranging from 0.14 to 0.3 W/mK, (e) static decay time of less than 2.0 sec.
Preparation of copolymers and melt blended composites
The following examples are given to illustrate the process of the present invention and should not be construed to limit the scope of the present invention.
Example 1
0.095 mole of aniline and 0.005 mole of o-isopropylaniline are taken in a double walled reaction vessel in which 1.0 N of hydrochloric acid is there and is kept at -2°C. The reaction mixture is stirred and drop wise aqueous solution of ammonium peroxydisulphate is added in two hours time. The reaction mixture is stirred for 6 hours, till a greenish precipitate of copolymer is obtained. The mixture is filtered and washed thoroughly with distilled water till the filtrate is colourless. The co polymer so obtained is treated with aqueous 0.1 M ammonia solution and stirred for 2 hours. The reaction mixture is again filtered and washed thoroughly with distilled water. The precipitate so obtained is vacuum dried at 55°C with constancy of temperature maintained to within +/-
1° C. The copolymer is then doped with 0.5 M Sodium 5-sulphoisophthalic acid, the copolymer is filtered and the green copolymer is dried at 60°C. The thermal stability of the copolymer so obtained is 285°C as carried out by Thermogravimetric analysis (TGA).
Example 2 0.095 mole of aniline and 0.005 mole of o-isopropylaniline are taken in a double walled reaction vessel in which 0.5 N of Sodium 5-sulphoisophthalic acid (NaSIPA) is there and is kept at -2°C. The reaction mixture is stirred and drop wise aqueous solution of ammonium peroxydisulphate is added in two hours time. The reaction mixture is stirred for 6 hours, till a greenish precipitate of copolymer is obtained. The mixture is filtered and washed thoroughly with distilled water till the colour of the filtrate is colourless. The copolymer so obtained is vacuum dried at 60°C with constancy of temperature maintained to within +/- 1°C. Thermal stability of the copolymer is 230 °C as carried out by Thermogravimetric analysis (TGA)
Example 3 0.090 mole of aniline and 0.010 mole of o-isopropylaniline are taken in a double walled reaction vessel in which 1.0 N of hydrochloric acid is there and is kept at -2°C. The reaction mixture is stirred and drop wise aqueous solution of ammonium peroxydisulphate is added in two hours time. The reaction mixture is stirred for 6 hours, till a greenish precipitate of copolymer is obtained. The mixture is filtered and washed thoroughly with distilled water till the colour of the filtrate is colourless. The co polymer so obtained is treated with aqueous 0.1 M ammonia solution and stirred for 2 hours. The reaction mixture is again filtered and washed thoroughly with distilled water. The precipitate so obtained is vacuum dried at 55°C with constancy of temperature maintained to within +/- 1° C. The copolymer is then doped with 0.5 M Sodium 5-sulphoisophthalic acid, the copolymer is filtered and the green copolymer is dried at 60°C. The thermal stability of the copolymer so obtained is 275°C as carried out by Thermogravimetric analysis (TGA).
Example 4 0.095 mole of aniline and 0.005 mole of o-sec butylaniline are taken in a double walled reaction vessel in which 1.0 N of hydrochloric acid is there and is kept at -2°C. The
reaction mixture is stirred and drop wise aqueous solution of ammonium peroxydisulphate is added in two hours time. The reaction mixture is stirred for 6 hours, till a greenish precipitate of copolymer is obtained. The mixture is filtered and washed thoroughly with distilled water till the colour of the filtrate is colourless. The co polymer so obtained is treated with aqueous 0.1 M ammonia solution and stirred for 2 hours. The reaction mixture is again filtered and washed thoroughly with distilled water. The precipitate so obtained is vacuum dried at 55°C with constancy of temperature maintained to within +/- 1° C. The copolymer is then doped with 0.5 M Sodium 5-sulphoisophthalic acid, the copolymer is filtered and the green copolymer is dried at 60°C. The thermal stability of the copolymer so obtained is 280°C as carried out by Thermogravimetric analysis (TGA).
Example 5 The copolymer having the ratio of aniline : 2-isopropyl aniline as 95:5 was melt blended with PET resin in a twin screw extruder having L/D ratio of 35.0 and keeping the barrel temperature at 285°C. The ratio of PET: copolymer was 99.8 : 0.2. The torque was maintained at 40-50 Nm and screw speed was 120 rpm. The melt blended strands were drawn and cooled to solidify. The strands were then palletized online to the cylindrical shape granules. The granules were dried for the period of 4 hours at 110°C under dynamic vacuum. The resultant composite granules show electrical conductivity of 3.72xl0-11 S/cm. The composite is thermally stable upto 438 °C and has melting point of 251 °C as determined from TGA and DSC respectively.
Example 6 The copolymer having the ratio of aniline: 2-isopropyl aniline as 95:5 was melt blended with PET resin in a twin screw extruder having L/D ratio of 35.0 and keeping the barrel temperature at 285°C. The ratio of PET: copolymer was 98.0 : 2.0. The torque was maintained at 40-50 Nm and screw speed was 120 rpm. The melt blended strands were drawn and cooled to solidify. The strands were then palletized online to the cylindrical shape granules. The granules were dried for the period of 4 hours 110°C under dynamic vacuum. The resultant composite granules show electrical conductivity of 3.26x10-10 S/cm. The composite is thermally stable upto 445 °C and has melting point of 255 °C as determined from TGA and DSC respectively.
Example 7
The copolymer having the ratio of aniline: 2-sec-butyl aniline as 95:5 was melt blended with PET resin in a twin screw extruder having L/D ratio of 35.0 and keeping the barrel temperature at 285°C. The ratio of PET: copolymer was 98.0 : 2.0. The torque was maintained at 40-50 Nm and screw speed was 120 rpm. The melt blended strands were drawn and cooled to solidify. The strands were then palletized online to the cylindrical shape granules. The granules were dried for the period of 4 hours 110°C under dynamic vacuum. The resultant composite granules show electrical conductivity of 3.26xl0-10 S/cm. The composite is thermally stable upto 440 °C and has melting point of 252 °C as determined from TGA and DSC respectively.
Example 8 A copolymer having the ratio of aniline: 2-isopropyl aniline as 95:5 was selected. The granules of melt blended composite having the ratio of PET: copolymer:: 98.0: 0.2, were processed in a single screw extruder having L/D ratio of 25.0 and compression ratio of 4:1 and keeping the barrel temperature at 295°C. The torque was maintained at 60-80 Nm and screw speed was 20 rpm. The extruded film show electrical conductivity of 2.62x10-11 S/cm. The composite film is thermally stable upto 435 °C and has melting point of 250 °C as determined from TGA and DSC respectively. The static decay time was less than 2 second as determined by static decay meter.
Comparative Example 1
0.095 mole of aniline and 0.005 mole of 2-isopropylaniline are taken in a double walled reaction vessel in which 1.0 N of hydrochloric acid is there and is kept at -2°C. The reaction mixture is stirred and drop wise aqueous solution of ammonium peroxydisulphate is added in two hours time. The reaction mixture is stirred for 6 hours, till a greenish precipitate of copolymer is obtained. The mixture is filtered and washed thoroughly with distilled water till the colour of the filtrate is colourless. The co polymer so obtained is treated with aqueous 0.1 M ammonia solution and stirred for 2 hours. The reaction mixture is again filtered and washed thoroughly with distilled water. The precipitate so obtained is vacuum dried at 55°C with constancy of temperature maintained to within +/- 1° C. The copolymer is then doped with 0.5 M HC1, the
copolymer is filtered and the green copolymer is dried at 60-80°C. The thermal stability of the copolymer was found to be 120°C
Comparative Example 2
0.095 mole of aniline and 0.005 mole of 2-isopropylaniline are taken in a double walled reaction vessel in which 1.0 N of hydrochloric acid is there and is kept at -2°C. The reaction mixture is stirred and drop wise aqueous solution of ammonium peroxydisulphate is added in two hours time. The reaction mixture is stirred for 6 hours, till a greenish precipitate of copolymer is obtained. The mixture is filtered and washed thoroughly with distilled water till the colour of the filtrate is colourless. The co polymer so obtained is treated with aqueous 0.1 M ammonia solution and stirred for 2 hours. The reaction mixture is again filtered and washed thoroughly with distilled water. The precipitate so obtained is vacuum dried at 55°C with constancy of temperature maintained to within +/- 1° C. The copolymer is then doped with 0.5 M dodecylbenzene sulphonic acid, the copolymer is filtered and the green copolymer is dried at 60-80°C. The thermal stability of the copolymer was found to be 210°C to 220°C.
Comparative Example 3
0.10 mole of aniline is taken in a double walled reaction vessel in which 1.0 N of hydrochloric acid is there and is kept at -2°C. The reaction mixture is stirred and drop wise aqueous solution of ammonium peroxydisulphate is added in two hours time. The reaction mixture is stirred for 6 hours, till a greenish precipitate of polymer is obtained. The mixture is filtered and washed thoroughly with distilled water till the colour of the filtrate is colourless. The co polymer so obtained is treated with aqueous 0.1 M ammonia solution and stirred for 2 hours. The reaction mixture is again filtered and washed thoroughly with distilled water. The precipitate so obtained is vacuum dried at 55°C with constancy of temperature maintained to within +/- 1° C. The polymer is then doped with 0.5 M dodecylbenzene sulphonic acid, the copolymer is filtered and the green copolymer is dried at 60-80°C. The thermal stability of the polymer was found to be 220°C to 230°C.
Comparative Example 4
0.10 mole of aniline is taken in a double walled reaction vessel in which 1.0 N of hydrochloric acid is there and is kept at -2°C. The reaction mixture is stirred and drop wise aqueous solution of ammonium peroxydisulphate is added in two hours time. The reaction mixture is stirred for 6 hours, till a greenish precipitate of polymer is obtained. The mixture is filtered and washed thoroughly with distilled water till the filtrate becomes colorless. The co polymer so obtained is treated with aqueous 0.1 M ammonia solution and stirred for 2 hours. The reaction mixture is again filtered and washed thoroughly with distilled water. The precipitate so obtained is vacuum dried at 55°C with constancy of temperature maintained to within +/- 1°C. The polymer is then doped with 0.5 M Sodium 5-sulphoisophthalic acid (NaSIPA), the copolymer is filtered and the green copolymer is dried at 60-80°C. The thermal stability of the polymer was found to be 300°C. The solubility of the said copolymer in MEG was relatively low.
Comparative Example 5
0.10 mole of aniline is taken in a double walled reaction vessel in which 0.5 N of Sodium 5-sulphoisophthalic acid (NaSIPA) is there and is kept at -2°C. The reaction mixture is stirred and drop wise aqueous solution of ammonium peroxydisulphate is added in two hours time. The reaction mixture is stirred for 6 hours, till a greenish precipitate of polymer is obtained. The mixture is filtered and washed thoroughly with distilled water till the filtrate becomes colorless. The polymer so obtained is vacuum dried at 55°C with constancy of temperature maintained to within +/- 1° C. The thermal stability of the polymer was found to be 210-220°C. The copolymer has good solubility in MEG.
Comparative Example 7
The PET granules were processed in a single screw extruder having L/D ratio of 25.0 and compression ratio of 4:1 and keeping the barrel temperature at 295°C. The torque was maintained at 60-80 Nm and screw speed was 20 rpm. The extruded film show electrical conductivity of 7.6x10-13 S/cm. The thermal stability is 433 °C and has melting
point of 250 °C as determined from TGA and DSC respectively. The static decay time was greater than 60 seconds.

We claim:
(1) A novel copolyaromatic amine of general formula as given below:
(Formula Removed)
wherein 'R' is selected from the bulky alkyl group containing 3 to 4 carbon atoms, wherein 'X" is a counter ion selected from the group consisting of sodium 5-sulphoisophthalic acid (NaSIPA), lithium 5-sulphoisophthalic acid (LiSIPA), wherein 'a' and 'b' are mole fraction of aniline and 2-isopropyl aniline in the resultant copolymer, wherein values of 'a' and 'b' is less than 1, wherein the molecular weight of the said copolymer is ranging between 20,000 to 80,000 g/mol, wherein the copolymer is having the following attributes:
(b) thermal stability upto 300°C, (b) electrical conductivity in the range of 5 S/cm to 10~2 S/cm, (c) free from benzidine during polymerization or heating to 300°C, (d) Soluble in the organic solvents like:
(i) monoethylene glycol (MEG), (ii) dimethyl sulphoxide (DMSO), (iii) dimethly formamide (DMF), (iv) N-methyl pyrrolidone (NMP), (v) tetrahydro furan (THF)
(2) A process for the preparation of copolyaromatic amines of the general formula (1) as
claimed in claim 1, wherein the process steps comprises:
(a) preparing aqueous solutions of aniline and substituted aniline in the distilled water, (b) mixing aqueous solutions of aniline and substituted aniline monomers in the presence of protonic acid, wherein pH is in the range of 0 to 3, at temperature in the range of-5.0°C to +5.0°C, (c) adding an aqueous solution of oxidant slowly drop by drop to the said mixture with continuous stirring and temperature maintained in the range of-5.0 to +5.0°C, (d) allowing the reaction mixture to polymerize for a time period in a range of 4-6 hours and under continuous stirring, (e) filtering the said reaction mixture after the completion of the copolymerization, (f) thoroughly washing the said mixture with doubly distilled water till the filtrate becomes colorless and
neutral in pH, (g) neutralizing the washed copolymer with aqueous alkali and drying the copolymer at a temperature in a range of 50-60°C under vacuum, till constant weight, (h) doping the neutralized copolymer with aqueous solution of protonic acid, under continuous stirring for 2-4 hours and pH is maintained in the range of 0-3, (i) filtering the doped copolymer on completion of doping process, (j) thoroughly washing the doped copolymer with doubly distilled water till the filtrate becomes colorless and neutral in pH, (k) drying the doped copolymer at a temperature in a range of 50-60°C under vacuum, till constant weight.
(3) A process as claimed in claim (2) wherein the doping of copolymer with dopant in step number (h) can also be carried out directly at the polymerization time.
(4) A process as claimed in claim (2) wherein the substituted aniline is selected from the group comprising of 2-isopropyl aniline, 2-sec-butyl aniline.
(5) A copolymer as claimed in claim 1 wherein the ratio aniline: substituted aniline is in the range of 95:5 to 50:50.

(6) A process as claimed in claim (2) wherein the concentration of aqueous solution of monomer as in step (a) is ranging between 0.1M to 2.0 M.
(7) A process as claimed in claim 2 wherein oxidant is selected from a group comprising of ammonium persulphate, potassium persulphate, sodium persulphate, ferric chloride, ferric p-toluene sulphonate.
(8) A process as claimed in claim 2 wherein wherein concentration of aqueous solution of oxidant is ranging between 0.1M to 2.0 M
(9) A process as claimed in claim 2 wherein protonic acid is selected from the group comprising of sodium 5-sulphoisophthallic acid (NaSIPA) or Lithium 5-sulphoisophthallic acid (LiSIPA).
(10) A process as claimed in claim 2 wherein neutralization of washed copolymer is
carried out from aqueous basic solution selected from the group comprising of
ammonium hydroxide, sodium hydroxide and potassium hydroxide.
(11) A melt blended composite comprising a copolymer as in claim 1, and a matrix
polymer is selected from the group comprising of PET, nylon, acrylics, polyamides,
high impact polystyrene (HIPS), polycarbonate (PC), polypropyleoxide (PPO) +
HIPS and a combination thereof, wherein amount of copolymer is ranging between 0.2-20.0 % by weight.
(12) A melt blended composite as claimed in claim 11 wherein the copolymer is
selected preferably from poly(aniline-co-2-isopropyl aniline) or poly(aniline-co-
2-sec-bytyl aniline).
(13) A composite as claimed in claim 11 wherein a melt blended composite have the
following properties:
(a) thermal stability upto 450°C, (b) free from benzidine on heating upto 300°C, (c) electrical conductivity ranging from 10-13 to 10-9 S/cm, (d) thermal conductivity ranging from 0.14 to 0.3 W/mK, (e) static decay time of less than 2.0 sec.
(14) A novel copolyaromatic amine, process of preparation thereof and a composite
therefrom substantially as herein described with reference to the examples and drawings
accompanying this specification.

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Patent Number

271553

Indian Patent Application Number

2646/DEL/2008

PG Journal Number

09/2016

Publication Date

26-Feb-2016

Grant Date

25-Feb-2016

Date of Filing

24-Nov-2008

Name of Patentee

COUNCIL OF SCIENTIFIC & INDUSTRIAL RESEARCH

Applicant Address

ANUSANDHAN BHAWAN, RAFI MARG, NEW DELHI-110 001,INDIA

Inventors:

#	Inventor's Name	Inventor's Address
1	DHAWAN SUNDEEP KUMAR	NATIONAL PHYSICAL LABORATORY, DELHI
2	SAINI PARVEEN	NATIONAL PHYSICAL LABORATORY, DELHI
3	JALAN RAJESH	RELIANCE INDUSTRIES LTD.,MUMBAI-400001

PCT International Classification Number

C08F8/30; C08F255/02;

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA