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

Definitions

• Conductive Polymer Compositions This invention relates to conductive polymer compositions and more particularly to fluid compositions based on polyaniline from which conductive fibres, films and coatings can be made.
• the emeraldine base form of polyaniline, doped with a sulfonic acid, is now well-established as a useful air-stable conductive polymer (and the leuco base form may also be useful) , but conventional fluid compositions only form good films if their solids content is rather small, and even then the films do not draw well.
• the present invention provides compositions which are capable of use in a wet-spinning process for the manufacture of drawn fibres; they are also useful for the manufacture of drawable films and of coatings by processes in which a competitive solvent is used to achieve solidification faster than is possible by solvent evaporation alone.
• the polymer composition in accordance with the invention is the reaction product of: (a) a polyaniline in base form;
• the sulfonic acid not only acts as a dopant to make the polyaniline conductive but also as a solvating agent to increase the "solubility" of the polymer (the word has been put in inverted commas because the mixtures are sometimes considered to be, at least partly, stable dispersions rather than true (fully solvated) solutions: a homogenising step will usually be required in forming them) .
• polyaniline is preferably as free of branching and other defects as possible, and polyanilines of the kind showing only two substantial peaks in their 13 C NMR spectra in the leuco base form, in accordance with W095/23822, are preferred.
• high molecular weight is normally also desirable, but this may not always be so if the mixture is for use in making coatings.
• the polyaniline is in its emeraldine base form; alternatively it is possible to use the leuco base form, though for most applications this will eventually need to be oxidised to the emeraldine form.
• the aliphatic sulfonic acid is preferably wholly free of ring structures (especialy aromatic ones), and ideally also free of bulky substituents .
• Polymerised or polymerisable aliphatic sulfonic acids have the advantage that they are less likely to migrate away from the polyaniline, and may therefore be preferred. High molecular weights are undesirable.
• Preferred functional groups are carbonyl, amido, amino and hydroxy, especially amido and carbonyl.
• ACES and most especially AMPSA (and its oligomers) are preferred.
• pK a values of aliphatic sulfonic acids are difficult to measure and not readily acessible, but it may be assumed that they all have pK a values lower than 1, and in many cases below 0.
• the proportion of sulfonic acid in the mixture may vary in the usual ranges; mostly a proportion in the range from
• the acid solvent has a pK a not greater than 4 and more especially not greater than 3 or better still 2 or even 1.5; preferably it is at least 0.5 units larger (more positive) than that of the sulfonic acid.
• carboxylic acids that meet these criteria and especially those with halogeno- substituents (meaning -Cl, -F or -CN) .
• the mixtures in accordance with the invention may include more than one such acid solvent; they may also include additional solvents (diluents) and/or host polymers that may become incorporated into the fibres, films or coatings; we prefer that they do not contain lithium chloride (or any inorganic electrolytes) .
• the fluid mixtures in accordance with the invention are green, indicating protonation of the polyaniline.
• the invention includes processes for making fibres, films and coatings characterised by the step of removing the acid solvent from the mixtures described by exposing the mixture to the action of a competitive solvent, by which is meant a liquid in which the acid solvent in the mixture is readily soluble but polyaniline is substantially insoluble.
• esters and ketones including in particular acetone, methylisobutyl ketone and butyl acetate are effective and suitable competitive solvents.
• Water may be too effective for some processes, as it is usually desirable for some of the acid solvent to remain as an aid to subsequent drawing (a plasticiser) and over-rapid solidification may not be conducive to optimum structure; but aqueous solutions of alcohols, ketones and esters may prove usable.
• the invention includes l.a process for the manufacture of polyaniline fibre which is a wet-spinning process in which the mixture described is caused to pass through the opening (s) of a spinneret into a bath of competitive solvent and the resulting filament optionally drawn simultaneously or subsequently;
• Both fibres and films can be cold-drawn (at room temperature) or drawn at elevated temperatures, up to about
• the polyaniline starting material for these examples is an emeraldine base prepared according to the teaching of W095/23822 and having a molecular weight (M p ) measured as described in that application of about 150,000 Daltons.
• M p molecular weight
• Polyaniline (3.467g) was ground by a pestle and mortar with AMPSA (4.533g, 57 molecules per hundred nitrogen atoms in the polyaniline) using a glove box with dry nitrogen atmosphere to avoid gelation.
• the ground mixture was added to dichloroacetic acid (92.0g) to give a mixture with a solids content of 8% by weight (or about 12%w/v, as the acid has a specific gravity of about 1.5).
• the mixture was homogenised for 10 minutes in a Ultraturrax homogeniser running at 20,000 rpm. The homogenisation/protonation is appreciably exothermic .
• a portion of the resulting dark green mixture was cast onto a 125 mm diameter polished silicon wafer and dried in an oven at 80 2 C for about 24 hours.
• the dried film was peeled from the substrate and found to be 0.202 ⁇ 0.004 mm thick; its electrical conductivity was measured using a 4- wire probe and found to be 177 ⁇ 6 S/cm.
• a dumbbell with a bar section 25 mm long and 4.0 mm wide was die-cut from this film and clamped in a stretching rig; it was heated to 110 2 C and then stretched slowly until the applied force reached 6.0 N. 5
• the bar portion of the sample was then 58 mm long (elongation 130%), 0.114 ⁇ 0.004 mm thick and 2.7 mm wide; its longitudinal conductivity was 540 S/cm.
• Polyaniline (0.632 g) was ground with AMPSA (0.868 g, 60
• Polyaniline (1.517 g) was ground with AMPSA (2.083 g, 60 molecules per hundred nitrogen atoms) and then added under nitrogen to dichloroacetic acid (36.4 g) over a 5-minute period while homogenising at 20,000 rpm, generally as in the preceding examples. Homogenising was continued for a further 10 minutes to obtain a 9%-solids mixture (by weight - about 15% w/v) .
• the mixture was transferred immediately, without cooling, to a cylindrical dope-pot 25 mm in diameter having at its bottom end a 140-micrometre filter and a spinneret consisting of a single hole with a diameter of 150 ⁇ m. The pot was removed from the glove box and promptly connected at its top end to a nitrogen gas supply.
• An electric heating tape was wrapped round the pot to enable it to be brought to and held at a temperature of 50 ⁇ 5 2 C, and its bottom end was dipped into two litres of cold butyl acetate in a measuring cylinder.
• the nitrogen pressure in the pot was raised to 0.7 MPa (100 psi) to spin a continuous filament, which was left in the butyl acetate for up to 10 minutes and then dried in air.
• the filament was measured with a micrometer and found to have a diameter of 0.30 ⁇ 0.01 mm, and examination with a scanning electron microscope (including examination of a surface formed by fracture at liquid nitrogen temperature) showed it to be smoothly cylindrical and without apparent voids or granules. Longitudinal conductivity of the filament was 70 ⁇ 9 S/cm.
• a ten-millimetre length of the filament was stretched at room temperature at a rate of about 10mm/sec, and was thus elongated into a fibre 50 mm long and with a uniform cross- section of 0.10 ⁇ 0.01 mm. Its conductivity was 810 ⁇ 200 S/cm and tensile strength at break about 45 MPa (breaking load 0.4 N) .
• Example 3 This was substantially the same as Example 3 except that the butyl acetate was replaced by acetone.
• the filament diameter (as formed) was 0.26 ⁇ 0.01 mm and
• a filament was made by the same procedure as in Example 4 but in this case the diameter of the filament as formed (which is very sensitive to precise conditions) was 15 found to be 0.15 mm; its conductivity was still about 90 S/cm.

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• Physics & Mathematics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Macromolecular Compounds Obtained By Forming Nitrogen-Containing Linkages In General (AREA)
• Paints Or Removers (AREA)
• Compositions Of Macromolecular Compounds (AREA)

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• 1998
  • 1998-10-30 EP EP98950224A patent/EP1029329A1/de not_active Withdrawn
  • 1998-10-30 CA CA002309194A patent/CA2309194A1/en not_active Abandoned
  • 1998-10-30 JP JP2000519900A patent/JP2001522898A/ja active Pending
  • 1998-10-30 AU AU96377/98A patent/AU9637798A/en not_active Abandoned
  • 1998-10-30 WO PCT/GB1998/003241 patent/WO1999024991A1/en not_active Application Discontinuation

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