Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
  • H01B1/06—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of other non-metallic substances
  • H01B1/12—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of other non-metallic substances organic substances
  • H01B1/124—Intrinsically conductive polymers
  • H01B1/128—Intrinsically conductive polymers comprising six-membered aromatic rings in the main chain, e.g. polyanilines, polyphenylenes
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/12—Powdering or granulating
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L27/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers
  • C08L27/02—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L27/04—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment containing chlorine atoms
  • C08L27/06—Homopolymers or copolymers of vinyl chloride
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
  • H10K85/10—Organic polymers or oligomers
  • H10K85/141—Organic polymers or oligomers comprising aliphatic or olefinic chains, e.g. poly N-vinylcarbazol, PVC or PTFE
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2327/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers
  • C08J2327/02—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment
  • C08J2327/04—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment containing chlorine atoms
  • C08J2327/06—Homopolymers or copolymers of vinyl chloride
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L65/00—Compositions of macromolecular compounds obtained by reactions forming a carbon-to-carbon link in the main chain; Compositions of derivatives of such polymers
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
  • H10K85/10—Organic polymers or oligomers
  • H10K85/141—Organic polymers or oligomers comprising aliphatic or olefinic chains, e.g. poly N-vinylcarbazol, PVC or PTFE
  • H10K85/146—Organic polymers or oligomers comprising aliphatic or olefinic chains, e.g. poly N-vinylcarbazol, PVC or PTFE poly N-vinylcarbazol; Derivatives thereof

Definitions

• the present invention relates generally to composite materials consisting of conventional thermoplastics and intrinsically conducting polymers (ICPs) and in particular to an electrically semi-conducting or conducting composite material and methods for forming same.
• the composite material has potential application in a wide range of devices including microwave devices, pressure sensors, temperature sensors, cable shielding, electromagnetic shielding, anti-static materials for computers and other applications, radar-absorbing materials, light weight battery electrodes, high-power junction devices, corrosion resistant electrodes and corrosion resistant cable termination coatings.
• a number of intrinsically conducting polymers have now been known for well over a decade.
• One of the most extensively characterised conducting polymers is polyacetylene. This polymer possesses a backbone with a high degree of unsaturation leading to ⁇ -orbital overlap and electron delocalisation. This delocalisation allows the polymer to possess a quite remarkable electrical conductivity when compared with traditional insulating polymers.
• the structure of this polymer is, however, quite unstable.
• polyheterocyclics such as polypyrrole and polythiophene.
• polypyrrole the repeat unit of this polymer is comprised of a 5-membered cyclic ring with two delocalised ⁇ bonds and a nitrogen heteroatom.
• Polypyrrole when produced using an electrochemical process can form a free standing film with an electrical conductivity as high as 100 S/cm.
• Polyheterocyclics have an improved stability in comparison to polyacetylene, the improved stability being provided by the aromatic nature of the heterocyclic ring which prevents loss of ⁇ bond unsaturation.
• thermoplastics With conventional thermoplastics with intrinsically conducting polymers, their use to date has been limited by poor environmental stability and poor mechanical properties. Poor processability and poor solubility have also prevented processing of the polymers using traditional polymer processing techniques.
• the blending of conventional thermoplastics with intrinsically conducting polymers leads to processable semi-conducting thermoplastics. Previously, this has been achieved by intimate mixing of thermoplastics with intrinsically conducting polymers either by solution processing (for example see A. Andreatta and P. Smith. Synthetic Metals (1993), 55-57. 1017) or by direct blending (for example see L.W. Shacklette, C.C. Han and M.H. Luly, Synthetic Metals ( 1993) 55-57, 3532).
• thermoplastic composite which requires at least 15% w/w intrinsic conducting polymer to achieve electrical conductivities comparable to that of the pure intrinsically conducting polymer. This is due to the nature of the microstructure of blends arising from these procedures. These methods of processing result in conduction through a dispersed phase consisting of flocculated structures. This behaviour results from what is termed a percolation network and is analogous to that observed when a thermoplastic is loaded with conventional conductors (such as silver particles) or semi-conductors (such as carbon black).
• polyethylene films the surface of which has been sulfonated, can be coated with pyrrole followed by a chemical oxidative polymerisation resulting in a conducting polymer coating on the surface of the film (for example see K. Yoshino, X.II. Yin. S. Morita, Y. Nakanishi. S. Nakagawa, S. Yamamoto. T. Watanuki and I. Isa, Japanese Journal of Applied Physics Part 1 (1993), 32, 979). Disclosure of the Invention
• the present invention consists in an electrically semi-conducting or conducting composite material comprising a plurality of electrically insulating thermoplastic particles coated with conducting or semiconducting polymer, the conducting or semiconducting polymer forming a network through the composite.
• the conducting or semiconducting polymer is soluble in organic or inorganic solvents and can comprise polyaniline or a polyaniline derivative.
• the polyaniline is preferably a doped polyaniline- camphorsulfonic acid in meta-cresol.
• the difference between the glass transition temperature and melting temperature of the thermoplastic material is preferably greater than 20°C thereby allowing pressing of the thermoplastic material in its rubbery state and avoiding melting and disruption of the morphology.
• the thermoplastic material is an amorphous polymer.
• the thermoplastic can comprise unplasticised or plasticised poly(vinyl chloride) (PVC).
• the plasticiser is preferably any additive which lowers the glass transition temperature of the material and can include internal plasticisers or an ester plasticiser such as dioctyl phthalate or dibutyl phthalate.
• the surface of the thermoplastic particles prior to coating with the conducting polymer is preferably treated to increase its wettability by the conducting or semiconducting polymer and so improve the adhesion between the coating and the particle.
• the surface treatment preferably comprises, plasma etching, chemical etching, or, most preferably, sulfonation in which sulfo groups. -SO3H, are bonded to the surface of the particles.
• the thermoplastic particles are preferably approximately spherical in geometry with a diameter less than 100 microns.
• the particles may also contain ferromagnetic particles to enhance electromagnetic shielding.
• the ratio of conducting polymer to thermoplastic material in the composite preferably lies in the range 0.1% w/w-20% w/w.
• the electrical conductivity of the composite preferably lies in the range 0.001-50 S/cm but can be varied over a larger range by appropriate doping of the conducting polymer.
• the percolation threshold of the composite is preferably less than 1% w/w of the conducting polymer.
• the present invention consists in an electrically insulating thermoplastic particle substantially coated with a layer of a soluble conducting polymer.
• the soluble polymer comprises a doped or undoped polyaniline or polyaniline derivative.
• the present invention consists in a method for preparing an electrically semi-conducting or conducting composite material comprising bringing together thermoplastic particles coated with conducting or semiconducting polymer under conditions of temperature such that the particles are bonded togetlier or coalesced without destroying the connectivity of the conductive coatings to produce a conductive network.
• thermoplastic particles can be substantially spherical sulfonated poly(vinyl chloride) particles coated with a layer of doped polyaniline.
• the temperature is preferably set between the glass transition temperature and the flow point of the thermoplastic.
• the temperature is preferably set in the range 145°C to 155°C.
• thermoplastic particles are also preferably brought together under pressure, the pressure being sufficiently low so as to prevent shear stress deforming the particles to a point where the conducting oi ⁇ semiconducting polymer coating is disrupted.
• the pressure may be applied by pressing or extrusion of the material.
• the present invention consists in a method for preparing a thermoplastic particle substantially coated with a layer of doped or undoped conducting polymer comprising the step of substantially coating the thermoplastic particle with a layer of doped or undoped conducting polymer.
• the particles are preferably coated by mixing the particles with a solution containing dissolved doped or undoped conducting polymer followed by a drying of the particles, if necessary, at an elevated temperature and under vacuum.
• the conducting polymer is preferably polyaniline.
• the polyaniline solution preferably comprising a doped polvaniline- camphorsulfonic acid in meta-cresol.
• the thermoplastic particles are preferably an amorphous polymer.
• poly(vinyl chloride) particles which have undergone a surface treatment prior to being mixed with the solution.
• the surface treatment preferably comprises a sulfonation process wherein sulfonate groups are bonded to the surface of the particles.
• the sulfonated particles are preferably soaked in a plasticiser prior to being mixed in the polyaniline solution.
• the plasticiser may comprise an ester plasticiser such as dioctyl phthalate or dibutyl phthalate.
• the addition of the plasticiser results in a composite having improved mechanical characteristics such as flexibility without lowering the electrical conductivity.
• the processability of the conducting thermoplastic composite improves its potential for use in a variety of applications.
• the composite can be utilised in a range of devices including microwave devices, pressure sensors, temperature sensors, cable shielding, magnetic shielding, anti-static materials for computers and other applications, radar-absorbing materials, light weight corrosion resistant electrodes, high-power junction devices and corrosion resistant cable termination coatings.
• Figure 1 is an optical micrograph of 4% PAn-CSA/PVC pressed at 150°C/28MPa;
• Figure 2 is an optical micrograph of 4% PAn-CSA PVC pressed at 200°C/28MPa;
• Figure 3 is a graph of electrical conductivity of the composite material as a function of loading of PAn-CSA/PVC
• Figure 4 is a graph of DMTA results for composite materials made according to the present invention having varying quantities of PAn- CS ⁇ /PVc:
• Figure 5 is a graph of DMTA results for composite materials made according to the present invention containing 4% PAn-CSA PVC and varying amounts of plasticiser. Best Method of Performing the Invention By way of example only, a preferred embodiment of the invention is described below.
• the resulting sulfonated poly(vinyl chloride) was then dried under vacuum for 24 hours.
• the degree of sulfonation was determined to be 1.0 x 10 ll, SO 3 groups/cm 2 .
• the particles were then suspended in petroleum spirit (80-100°C fraction) (200 millilitres) containing dioctyl phthalate (DOP) (10 grams) and the solvent was allowed to slowly evaporate.
• DOP dioctyl phthalate
• the composite material as prepared using the process described in Example 1 had a conductive network of PAn-CSA 10 around the poly(vinyl chloride) (PVC) particles 20 as is clearly depicted in Figure 1.
• Pressing an identically prepared sample of composite at a temperature exceeding the flowpoint of the PVC (ie. at 200°C) resulted in destruction of the network morphology in the composite as is clearly depicted in Figure 2.
• Further samples having varying weight fractions of PAn-CSA in PVC were prepared with the electrical conductivity of the composites being determined by the standard 4-probe measurement. The results are depicted in Figure 3. It can be readily seen from Figure 3 that the percolation threshold of the composite is less than 1% w/w PAn-CSA.
• the sample prepared using the method described in Example 1 was measured to have an electrical conductivity of 1.2 S/m using a standard 4-probe measurement.
• the conducting composite prepared using the method defined in Example 1 while not having mechanical properties identical to PVC does have improved mechanical properties in comparison to intrinsically conducting polymers.
• DMTA studies in bending mode on samples prepared as described in Example 1 but with varying quantities of PAn-CSA showed a substantial change in the softening temperature of the samples with increasing PAn-CSA loading. Softening occurs around 70°C for all samples (cf:90°C for PVC pressed in an identical manner). Notably, below 65°C there is almost no difference in modulus, the stiffness being comparable to that of
• the conductivity of the composite is effected when pressed at 150°C, due to the low softening temperature ( ⁇ 50°C).
• the high processing temperature relative to the 30% DOP softening temperature leads to the destruction of the connective morphology shown in Figure 1, and the formation of a morphology similar to that shown in Figure 2.
• the processability of the composite also allows the material to be employed in a wide range of applications as hereinbefore described.

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• 1996
  • 1996-01-10 WO PCT/AU1996/000009 patent/WO1996021694A1/en not_active Application Discontinuation
  • 1996-01-10 EP EP96900206A patent/EP0802943A4/de not_active Withdrawn

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