WO2008055311A1 - Nanocomposites polymères - Google Patents

Nanocomposites polymères Download PDF

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Publication number
WO2008055311A1
WO2008055311A1 PCT/AU2007/001720 AU2007001720W WO2008055311A1 WO 2008055311 A1 WO2008055311 A1 WO 2008055311A1 AU 2007001720 W AU2007001720 W AU 2007001720W WO 2008055311 A1 WO2008055311 A1 WO 2008055311A1
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nanocomposite
pan
pmas
electrochromic
electrically conducting
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PCT/AU2007/001720
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English (en)
Inventor
Gordon George Wallace
Peter Helena Hubertus In Het Panhuis
Peter Charles Innis
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University Of Wollongong
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Priority claimed from AU2006906284A external-priority patent/AU2006906284A0/en
Application filed by University Of Wollongong filed Critical University Of Wollongong
Publication of WO2008055311A1 publication Critical patent/WO2008055311A1/fr

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    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • 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
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/005—Reinforced macromolecular compounds with nanosized materials, e.g. nanoparticles, nanofibres, nanotubes, nanowires, nanorods or nanolayered materials
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L101/00—Compositions of unspecified macromolecular compounds
    • C08L101/12—Compositions of unspecified macromolecular compounds characterised by physical features, e.g. anisotropy, viscosity or electrical conductivity
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L79/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen or carbon only, not provided for in groups C08L61/00 - C08L77/00
    • C08L79/02—Polyamines
    • 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
    • H01B1/127—Intrinsically conductive polymers comprising five-membered aromatic rings in the main chain, e.g. polypyrroles, polythiophenes
    • 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
    • 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
    • H01B1/20—Conductive material dispersed in non-conductive organic material

Definitions

  • the invention relates to polymeric nanocomposites that are electrically conducting.
  • the use of such composites in optical and electrochemical devices including electrochemic devices are of particular interest.
  • an electrically conducting polymeric nanocomposite comprising a first electrically conducting polymer and a second electrically conducting polymer which acts as a dopant of the first electrically conducting polymer.
  • the second electrically conducting polymer may act as stabiliser for the first electrically conducting polymer.
  • one or both polymers in the polymeric nanocomposite are electroactive and/or electrochromic, resulting in a conducting electroactive and/or electrochromic polymeric nanocomposite.
  • the electrically conducting polymeric nanocomposite is selected from the group consisting of Polyaniline (PAn) / poly (2-methoxyaniline-5-sulfonic acid) (PMAS), Polypyrrole (PPy)/ PMAS, Polythiophene (PTh) /PMAS, PAn / polypyrrole- sulphonic acid, PPy/ polypyrrole- sulphonic acid, Polythiophene (PTh) / polypyrrole- sulphonic acid, PAn / polythiophene- sulphonic acid, PPy / polythiophene- sulphonic acid, PTh / polythiophene- sulphonic acid, PPy or PAn or PTh/methoxyaniline (POMA) , and PPy or PAn or PTh /alkylcarboxy pyrrole diethoxy.
  • PAn Polyaniline
  • PMAS poly (2-methoxyaniline-5-sulfonic acid)
  • PMAS Polypyr
  • the ratio of the first polymer to the second polymer is 1:0.05-20.0, more preferably 1:1.5
  • the polymeric nanocomposite may further include nanotubes, and the second polymer may also act as a stabliser for the nanotubes.
  • the nanotubes are multi walled carbon nanotubes (MWNT) .
  • MWNT multi walled carbon nanotubes
  • the amount of nanotubes in the nanocomposite is less than 32%w/v, more preferably in the range of 10%w/v to 32%w/v.
  • the nanocomposite is PAn/PMAS/MWNT in a ratio of 1:2.2:1.35.
  • the nanocomposite may include nanofibres with diameters in the range of 30 to 50nm and lengths in the range of 100 to 50,000nm, preferably in the range 100 to 5000nm; and nanoparticles with diameters in the range of 20 to lOOnm.
  • the polymeric nanocomposite may be in the form of a nanodispersion, wherein the nanocomposite is dispersed in an aqueous solution, preferably in the range of 0.1%w/v to 15%w/v and more preferably in the range of 0.1%w/v to 1.0%w/v.
  • a method for preparing an electrically conducting polymeric nanocomposite comprising polymerisation of the constituent monomer (s) of a first electrically conducting polymer in the presence of the second electrically conducting polymer which acts as a dopant of the first electrically conducting polymer.
  • the method may also include the step of dispersing nanotubes in the second electrically conducting polymer.
  • the second electrically conducting polymer may act as a stabiliser for the nanotubes.
  • a device which is wholly or partly composed of the nanocomposite defined above.
  • the device may be an optical or electrochemical device including an electrochromic device .
  • an electrochromic device comprising, (a) a first electrically conducting substrate;
  • the first electrochromic polymeric nanocomposite comprises a first electrically conducting polymer and a second electrically conducting polymer which acts as a dopant of the first electrically conducting polymer.
  • the first electrochromic polymer nanocomposite may further include nanotubes .
  • the polymeric nanocomposite is selected from the group consisting of polyaniline (PAn) / poly (2- methoxyaniline-5-sulfonic acid) (PMAS) , polypyrrole (PPy) / PMAS, polythiophene (PTh) /PMAS, PAn / polypyrrole- sulphonic acid, PPy/ polypyrrole- sulphonic acid, polythiophene (PTh) / polypyrrole- sulphonic acid, PAn / polythiophene- sulphonic acid, PPy / polythiophene- sulphonic acid, PTh / polythiophene- sulphonic acid, PPy or PAn or PTh/methoxyaniline (POMA) , PPy or PAn or PTh /alkylcarboxy pyrrole diethoxy, and PAn/PMAS/multi-walled Carbon nanotubes (MWNT) .
  • PAn polyaniline
  • PMAS polypyr
  • the nanocomposite is PAn/PMAS/MWNT and the amount of MWNT in the nanocomposite layer is less than 30%w/v, most preferably in the range of 10%w/v to 32%w/v.
  • each polymeric nanocomposite layer is deposited using inkjet printing or air brush spraying of a nanodispersion containing the polymeric nanocomposite .
  • the device may further include an electrolyte located between the first and second electrochromic layers.
  • One of the substrate layers in the device may also be reflective or include a reflective layer.
  • the second electrochromic polymer is a polymeric nanocomposite.
  • an electrochromic device comprising at least one electrochromic nanocomposite layer which comprises the steps of:
  • the second electrochromic polymer may be a second polymeric nanocomposite and the layer is formed by applying a nanodispersion containing the second polymeric nanocomposite to the first electrochromic layer.
  • the method may further include the step of laying a reflective layer between the first substrate and the first electrode.
  • the first substrate may have a reflective surface.
  • the nanodispersion is applied using an inkjet printer or airbrush sprayer.
  • the polymeric nanocomposite is selected from the group consisting of polyaniline (PAn) / poly (2- methoxyaniline-5 -sulfonic acid) (PMAS), polypyrrole (PPy)/ PMAS, polythiophene (PTh) /PMAS, PAn / polypyrrole- sulphonic acid, PPy/ polypyrrole- sulphonic acid, polythiophene (PTh)/ polypyrrole- sulphonic acid, PAn / polythiophene- sulphonic acid, PPy / polythiophene- sulphonic acid, PTh / polythiophene- sulphonic acid, PPy or PAn or PTh/methoxyaniline (POMA) , PPy or PAn or PTh/methoxyaniline (POMA) , PPy or PAn or PTh/methoxyaniline (POMA) , PPy or PAn or PTh/methoxyaniline (POMA)
  • nanocomposite is PAn/PMAS/MWNT.
  • the first substrate may be stored on a first roll, and the end of the first roll is fed onto a second roll, and an electrochromic device is printed onto the substrate exposed between the first and second rolls.
  • a method for printing an electrically conducting nanocomposite stratum comprising using an inkjet printer to apply one or more electrically conducting nanocomposite layers onto a substrate layer, wherein the inkjet printer prints a nanodispersion containing an electrically conducting nanocomposite comprising a first electrically conducting polymer and a second electrically conducting polymer which acts as a dopant of the first electrically conducting polymer.
  • the nanocomposite may be electroactive and/or electrochromic .
  • Figure 1 shows UV-vis spectra of (a) PAn/HCl, (b) PMAS and (c) PAn/PMAS (an embodiment of the invention) dispersions (0.0025% w/v) in (A) water and (B) 0.1 M NaOH (pH 13). These spectra are discussed below in the Examples section under the heading "Structure” .
  • Figure 2 depicts the cyclic voltamograms of PAn/HCl and an embodiment of the invention, PAn/PMAS, drop coated onto a glassy carbon electrode (250 ⁇ g/cm2) in 0.1 M HCl, scan rate 50 mV/sec.
  • Redox couples labels are discussed in the section "Electroactivity" properties below.
  • Figure 3A provides transmission electron microscopy (TEM) images of PAn/HCl (scale bar 500 nm) .
  • Figure 3B provide TEM images of PAn/PMAS (scale bar 2000 nm) .
  • Figure 4 shows the stability of PAn/HCl and PAn/PMAS aqueous dispersions (0.005 % w/v) after 3 days.
  • Figure 5 depicts the rheological properties of PAni-PMAS dispersions .
  • Figure 6 shows the surface tension properties of PAni-PMAS dispersions
  • Figure 7 depicts the cyclic voltammograms obtained for sprayed ( ) and printed (—) PAn/PMAS dispersion on Shedahl-200 ⁇ .
  • Figure 8 provides visible absorption spectra obtained for PAn-PMAS dispersions sprayed on ITO coated plastic. Spectra for oxidized/reduced spectra clearly shows the electrochromic effect .
  • Figure 9A and Figure 9B provides photographs of ITO electrodes coated with PAn-PMAS dispersion in the oxidized (more opaque; Figure 9A) and reduced (more transparent; Figure 9B) form.
  • Figure 1OA is a TEM image of MWNTs in the composite of PAn/PMAS/MWNT (1 Pan :2.2 PMAS : 1.7 MWNT).
  • Figure 1OB is a graph showing the sheet resistance as a function of MWNT loading fraction in free standing composite films. [Insets: photographs of composite dispersions with increasing MWNT loading (top) and a free standing film (bottom)].
  • Figure 11 shows UV-visible absorption spectra (normalised) of PAn/PMAS/MWNT dispersions. Arrows indicate the effect of increasing MWNT loading, e.g. decrease in 450 nm band, increase in absorbance above 500 nm.
  • Figure 12 shows a thermogravimetrie analysis spectrum of starting materials (A) and carbon nanotube composite materials (B) .
  • the number in B indicates the MWNT loading fraction.
  • Figure 13A shows a graph of sheet resistance (squares) and optical transparency (triangles) as a function of printed composite (10 mm x 35 mm, MWNT loading fraction 17.5%) layers on PET substrate at drop spacing 15 ⁇ m.
  • Figure 13B a printed photographic image (15 mm x 15 mm, MWNT loading fraction 32 %) .
  • Figure 13C is a printed test pattern (25 mm x 45 mm, MWNT loading fraction 32%) .
  • Figure 14 is a Cyclic voltammogram of a composite film (MWNT loading fraction 17.5 %) prepared by cast onto glassy electrode (0.535 mg/cm2) in 0.1 M HCl, scan rate 50 mV/s.
  • Figures 14V show photographs of printed film on Au-PVDF switched to yellow (-0.20 V; (C)) and blue (0.80 V; (D)).
  • Figure 15 shows cyclic voltammogram of composite film PAn/PMAS/MNTW (loading fraction 3.4%) printed onto Pt- ITO in 1 M HCl, scan rate 500m V/s.
  • Figure 16 shows transmission spectra of PAn/PMAS/CNT vs ProDOT (A) , PAn/PMAS vs ProDOT (B) , PMAS vs ProDOT (C) and PMAS/Prussian Blue vs ProDOT (D) .
  • Figure 17 shows various electrochromic devices constructed using one or more electrochromic layers comprised of a electrochromic nanocomposite.
  • Figure 17a shows the layers forming an electrochromic device
  • Figure 17b illustrates construction using two elements
  • Figure 17c shows an electrochromic device with a reflective layer
  • Figure 17d illustrates an electrochromic device in which electrochromic layers also function as electrodes .
  • Figure 18 shows a digital display element constructed from electrochromic segments.
  • Figure 19 shows the polymerisation of aniline monomers to polyaniline (PAn) in the presence of poly (2- methoxyaniline-5-sulfonic acid) (PMAS) .
  • Figure 20 is a flowchart of the method for preparing a nanocomposite of the present invention.
  • Figure 21 is a flowchart for constructing an electrochromic device using a nanocomposite of the present invention.
  • Nanomaterials are materials which have structural features of nanometre (nm) scale in at least one dimension. Nanometre scale typically refers to feature sizes of around 1 to several hundred nanometres, but often extends outside of this, including up to micron or more.
  • One dimensional nanomaterials include layers, thin films, surface coatings; two dimensional nanomaterials includes nanowires, nanofibres and nanotubes, and three dimensional nanomaterials include nanoparticles, nanorods, and quantum dots where the diameters or each dimension of the nanoparticle is less than a few hundred nanometres.
  • Nanoparticles may be substantially spherical, ellipsoidal, rodlike or irregularly shape and be of nanometre scale in two or three dimensions. Nanorods have aspect ratios (length to width) between about 3 and 5. However nanoparticle is sometime used interchangeably with nanomaterials to refer to particles with nanometre scale features or diameter on one, two or three dimensions.
  • Nanofibres may be coiled, elongated and/or rodlike.
  • Nanotubes are typically small cylinders made of organic or inorganic materials .
  • Known types of nanotubes include carbon nanotubes (CNTs) , metal oxide nanotubes such as titanium dioxide nanotubes and peptidyl nanotubes .
  • CNTs are sheets of graphite that have been rolled up into cylindrical tubes.
  • the basic repeating unit of the graphite sheet consists of hexagonal rings of carbon atoms, with a carbon-carbon bond length of about 1.45 A.
  • the nanotubes may be single-walled nanotubes (SWNTs) or multi-walled nanotubes (MWNTs) .
  • SWNTs single-walled nanotubes
  • MWNTs multi-walled nanotubes
  • a typical SWNT has a diameter of about 1.2 to 1.4nm.
  • Nanotubes may have up to 100 times the mechanical strength of steel and can be up to 2mm in length. They exhibit the electrical characteristics of either metals or semiconductors, depending on the degree of chirality or twist of the nanotube . Different chiral forms of nanotubes are known as armchair, zigzag and chiral nanotubes.
  • the electronic properties of carbon nanotubes are determined in part by the diameter and length of the tube .
  • nanoscale features and high surface area to volume of nanomaterials confer some new or enhanced properties over the macroscale material (ie the same material, but with larger features) .
  • Nanocomposites are materials in which nanoparticles are added to, or embedded in, a matrix.
  • the matrix is a polymer matrix.
  • the nanoparticles are typically dispersed throughout the matrix and may only comprise a small percentage of the total weight of the nanocomposite.
  • Nanocomposites typically exhibit new or modified properties compared to the properties of one or more of the components. These properties may be physical, chemical, electrical, optical, electrochemical, electrochromic, etc. in nature.
  • nanocomposite materials depend not only on the properties of the components but also on the morphology and interfacial characteristics of the resulting nanocomposite. Hence whilst the properties of the resulting nanoncomposite may be influenced by the choice of the nanoparticle (s) and matrix the actual characteristics of the resulting nanocomposite arise through the interaction of the characteristics of the components, and thus may be substantially different.
  • Nanocomposite may also include other components which influence its properties such as nanotubes, metals, metal oxides and carbon e.g. bucky balls and graphene.
  • the polymeric nanocomposite of the present invention comprises at least two electrically conducting polymers .
  • the nanocomposites possesses both optical and electrochemical properties.
  • the electrical conductivity of each polymer may be the same or different, generally greater than 1 S/cm, preferably in the range of 10 mS/cm to 100 S/cm.
  • Examples of suitable classes of conducting polymers include polypyrroles, polythiophenes, polyanilines, polyphenylene vinylenes, biological polyelectrolytes and/or derivatives thereof.
  • the choice of polymers will determine the properties of the resulting polymer nanocomposite.
  • the end product can be tailor made by effective choice of the polymeric components.
  • the properties of high conductivity can be found in the polyanilines (PAn) and polyaniline derivatives such as water soluble polyaniline, poly (2-methoxyaniline-5 sulfonic acid (PMAS) .
  • PAn polyanilines
  • PMAS poly (2-methoxyaniline-5 sulfonic acid
  • the properties of biocompatibility and therefore suitability for medical applications can be found in the polymer class of polypyrroles and derivatives thereof .
  • the electronic properties of the polymer class of polythiophenes and derivatives thereof are suitable for polymer solar cells .
  • the polymer class of polyphenylene vinylenes are also suitable for solar applications.
  • Biopolytes such as DNA may function as semiconductors .
  • a combination of polymers with different properties may be combined for certain applications.
  • Derivatives of the conducting polymers may include optionally substituted and/or salts comprising of the conducting polymers or the constituent monomers.
  • optionally substituted refers to a group that may or may not be further substituted with one, two or more groups selected from negatively charged sulphonate groups, sulphonic acid, Ci -6 alkyl, C 3 . 6 cycloalkyl, C 2 - 6 alkenyl, C 2 . 6 alkynyl, aryl, heterocycylyl , halo, haloC ⁇ .
  • Suitable salts of the conducting polymers include anionic sufonates, anionic carboxylates, cationic ammonium and/or cationic anilinium salts .
  • the optional substituent or salt is selected from C ⁇ - 4 alkoxy groups such as methoxy groups and/or ethoxy, sulphonate groups and sulphonic acid groups. It will be appreciated that more than one optional substituent and/or salt may be present on the conducting polymer or its constituent monomer (s) .
  • the groups that may be used as optional substituents or salts are charged species, making them more suitable in the present invention.
  • the nanocomposite may also include other components which influence its properties such as nanotubes, metals, metal oxides and carbon e.g. bucky balls and graphene.
  • nanotubes for example SWNTs and/or MWNTs in the polymeric nanocomposite can result in better optical and electrical properties of the nanocomposite.
  • the nanotubes are SWNTs and/or MWNTs .
  • the nanotubes are MWNTs.
  • the amount of nanotubes present in the nanocomposite can alter the optical properties and conductivity. For example, changing the amount of nanotube in a nanocomposite deposited on transparent substrates (see example 13, MWNT loading fraction changed from 17.5% to 32%) resulted in changes in optical transmittance (30-70%) and sheet resistance (1000-5000 ⁇ /cm2) . This is further demonstrated in the examples below (see Figure 13 and Table 3) .
  • a second conducting polymer may be selected from derivatives of the polymers described above, including derivatives of the first polymer.
  • the ratio of the two conducting polymers in the polymeric composite depends on the choice of polymers. Generally, a range of 0.1 - 2 (first polymer) : 0.1 to 2 (second polymer) is envisaged (equivalently 1:0.05-20). In an embodiment including nanotubes, generally a range of 1 (first polymer) : 2.2 (second polymer) : 0.1 - 2.7 (nanotubes) is envisaged.
  • a polymeric nanocomposite consisting of Polyaniline (PAn) and poly (2-methoxyaniline-5-sulfonic acid (PMAS) has a ratio range of 0.1 - 2 (Pan): 0.1 - 2 (PMAS) .
  • PAN Polyaniline
  • PMAS poly (2-methoxyaniline-5-sulfonic acid
  • a Pan/PMAS composite has a ratio of l(Pan) : 1.5 (PMAS) .
  • PMAS poly(Pan) : 1.35
  • CNT 1.35
  • polymeric composites of the present invention include: Polyaniline / poly (2-methoxyaniline-5-sulfonic acid) ;
  • Polyaniline / polythiophene- sulphonic acid Polypyrrole / polythiophene- sulphonic acid; Polythiophene / polythiophene- sulphonic acid; PPy or PAn or PTh/methoxyaniline (POMA) ; PPy or PAn or PTh /alkylcarboxy pyrrole diethoxy,- and.
  • Nanocomposites of polyaniline / poly (2- ⁇ nethoxyaniline-S- sulfonic acid) (PAn/PMAS) and PAn/PMAS/MWNT are preferred.
  • the nanocomposite may contain nano-particles and nanofibres.
  • the nano-particles may be spherical in shape.
  • the nano-fibres may be coiled, elongated and/or rodlike.
  • the diameter of the nano- fibres and/or nano-particles may be in the range of 1 and 500nm, preferably in the range of 5 to 300nm, more preferably in the range of 10 to 200nm, even more preferably in the range of 20 to lOOnm.
  • the length of the nano-fibres may be greater than lOOnm to several micrometers, preferably greater than 500nm.
  • PAn/PMAS nanocomposite has a diameter of 50 to 80nm.
  • spherical nano-particles of diameters in the range of 20 to lOOnm are present.
  • the length of the nano fibres may range from 1000 to 5000nm.
  • a PAn/PMAS nanocomposite contains nanofibres with a diameter of 30 to 50 nm and a length of 100 to 5000 nm. In a further embodiment, a PAn/PMAS/MWNT nanocomposite contains nanofibres with a diameter of 30 to 50 nm and a length of 100 to 50,000 nm.
  • the polymeric composite can be in the form of a nanodispersion.
  • nanodispersion refers to the dispersion of the nanocomposite in an aqueous solution.
  • the nanodispersions are stable at pH values of 9 or 10 without the aid of an additional stabiliser (steric or ionic) .
  • the nanodispersions may contain up to 20% w/v of the nanocomposite in aqueous solution, 0.05 to 15% w/v, more preferably 0.1 to 1.0% w/v.
  • the nanocomposite includes nanotubes, the nanotubes may be present in an amount up to 32 % w/v.
  • the 0.8 % w/v PAn/PMAS nanocomposite dispersion showed stability over a 3 to 6 month period and up to several years. This example also displayed conductivity of about 2.8cm/S. It is hypothesized that extended pH stability has been achieved via SO 3 H functionality of the PMAS.
  • PAn/PMAS/MWNT nanocomposite dispersion (1 (PAn): 2.2 (PMAS) : 1.35 (MWNT) at a concentration of about 1.0 w/v in aqueous solution
  • PAn PAn/PMAS/MWNT nanocomposite dispersion
  • PMAS PMAS
  • MWNT nanocomposite dispersion
  • This example in the form of a free standing film, also displayed sheet resistance and conductivity of 5 ⁇ /cm 2 and 51.3 S/cm respectively.
  • the combination of conducting polymers with conducting nanotubes such as carbon nanotubes has shown to have all the demanding characteristics needed for inkjet printing. These materials may be deposited onto substrates such as photo paper, PET, Pt-ITO and Au-PVDF. A sheet resistance of 500 ⁇ /cm 2 was attained for a single printed layer on photo paper .
  • the term “electroactive” generally refers to the ability of a material to be rapidly and reversibly switched between different oxidation states. This redox switching provides a facile mechanism for both the uptake (during oxidation) and release (during reduction) of a wide range of anions.
  • the polymeric nanocomposite is electroactive.
  • one or both of the polymers making up the polymeric composite may be separately electroactive.
  • the polymers making up the polymeric composite are each electroactive and also result in a polymer composite that is electroactive.
  • electroactivity was investigated.
  • the example of the polymer nanocomposite Pan/PMAS was investigated and discussed in the examples section below.
  • both sprayed and coated surfaces displayed well defined electrochemical switching characteristics (Figure 7) . This is important for a range of applications including printable electrochromics, batteries or even switchable hydrophobic / hydrophilic surfaces.
  • the switchable electrochromic properties of both printed and sprayed substrates are clearly illustrated in Figure 8 and Figure 9.
  • the method for preparing an electrically conducting polymeric nanocomposite is outlined in Figure 20 and comprises the steps polymerising the monomers of a first first electrically conducting polymer in the presense of a second electrically conducting polymer (112) .
  • the nanocomposite includes other components such as nanotubes (102; 104)
  • the nanotubes may be dispersed in the second conducting polymer (106) .
  • the constituent monomers of the first conducting polymer are then polymerised in the presence of the nanotubes dispersed in the second conducting polymer (108) .
  • the polymerisation may be performed using any suitable known technique, such as, the addition of an oxidant.
  • the oxidation can be conducted electrochemically or via the addition of an oxidising agent.
  • oxidants include ammonium persulphate (APS) , iron salts and/or cerium salts.
  • Electrochemical oxidation can be conducted using any suitable known technique such as electrolysis, for example, bulk electrolysis or flow-by electrolysis apparatus .
  • the dispersion of the other components such as nanotubes, in the second conducting polymer can be achieved using ultrasonic treatment.
  • the process involves the templating of monomers of the first polymer on the second polymer to form a first monomer and second polymer complex.
  • the template of the second polymer forces its conformation on the first polymer due to interaction between the monomer (s) of the first polymer and the electrolytic moieties on the second polymer prior to polymerisation.
  • Polymerisation of the first monomer such as by the addition of an oxidant results in a templated complex.
  • the resultant composite may then be conformationally trapped, thereby attaining the spectral aspects of the second polymer.
  • this conformation arises from the anilinium ion of the monomer of PAn to be oxidised via ion-pairing with the sulfonate of the templating PMAS as illustrated in Figure 19.
  • the second polymer then functions in a dual role as a molecular dopant and stabiliser resulting in the formation of nanoparticles .
  • the second polymer is also an excellent stabiliser for the other components, in particular for CNTs, while continuing to function as the dopant in the polymerisation of the constituent monomer (s) of the first polymer.
  • the polymerisation be conducted at a rapid rate rather than slowly. Bulk addition of the constituent monomer (s) of the first polymer and the second polymer is preferred and the polymerisation proceeds to completion with no stirring.
  • a nanodispersion may be formed by dispersing the electrically conducting nanocomposite in an aqueous solution (114) which may then be applied to a substrate (116) such as with a inkjet printer.
  • Devices composed partly or wholly of the electrically conducting polymeric nanocomposites are suitable for use in optical and electrochemical applications including electrochromics, electromagnetic shielding and/or controlled drug release.
  • These articles may include polymer actuators, polymer photovoltaics, polymer solar cells, rechargable polymeric batteries, anti-corrosion coatings, textile coatings, fuel cells, ink jet printing, bioconductors for controlled release or regeneration of mammalian cells.
  • the nanocomposite can also be used as a dye to coat textile fibres rendering them conductive.
  • Electrochromic mirrors for altering the intensity of reflected light, incident upon the mirror.
  • Mirrors which are capable of reversibly dimming may be used in the automotive industry.
  • the arrangement could be used in electrochromic glazing where a change in colour or transmissivity of an assembly can provide a dimming condition to a window or other type of screen. This dimming can increase the level of privacy to an area as well as control the level of radiant heat that permeates an area.
  • Electrochromic glazing may be used in many industries including the automotive industry, architectural, industrial and aeronautical industries, etc.
  • Electrochromic devices incorporating nanocomposites of the present invention may also have applications in visual displays for example, in projector light modulators which may improve upon current LCD projector technology.
  • the visual displays incorporating the present invention could be used in advertising. Manipulation of electric fields may allow an advert to be displayed on an electronic billboard. The advert could be readily replaced by varying the electric potential thereby providing the ability to display a number of advertisements on one billboard.
  • the dimming of the electrochromic assembly may be advantageously used in the ophthalmics industry.
  • the tint and colour of lenses could be manually or automatically adjusted in order to modify the amount of light transmitted to the eyes .
  • Colour control may have applications in the fashion industry where flexible laminates or woven fibres comprising the present system may provide a multitude of different colours in fabrics, jewellery and make-ups. It is also an option that the changes in colour be used for internal furnishing, for example, wallpaper which can change colour upon application of an applied potential.
  • An electrochromic device may be constructed using nanocomposites of the present invention.
  • a typical electrochromic device comprises two complimentary electrochromic materials and an electrolyte sandwiched between two electrodes .
  • Electrochromic materials forming electrochromic layers 12 and 14 are coloured according to the frequencies of light that are absorbed by the electrochrome.
  • the electrochromes which form the electrochromic layers 12 and 14 are selected to have absorption spectrum which are complementary to one another so that electrochromic layer 12 is anodically colouring while electrochromic layer 14 is cathodically colouring (complimentary electrochromic) .
  • electrochromic layer typically two complimentary electrochromic materials are preferred as they provide greater stability as electrons released by one material are taken up by the other, and greater contrast difference as they either both transparent or both coloured.
  • An electrolyte may be interposed between the electrochromic layers .
  • the electrolyte may be in the form of a liquid including an ionic liquid, a liquid infused membrane or support matrix, a gel or solid.
  • the electrolyte can be a combination of ionic liquids, an ionic liquid and a non-inherently liquid salt such as NaCl, or ionic liquid and solvent, or any combination of these mixtures.
  • the electrolyte may be a polymer having anionic or cationic functionalities.
  • the electrolyte can be a salt having a supporting solvent. Examples include LiC10 4 /acetonitrile, 1-ethyl-3-methyl imadozolium [BMIM] bistrifluoromethane sulfonimide or [BMIM] [BF 4 ] .
  • electrochromic layers may be in direct contact with each other and capable of ion or charge exchange .
  • the electrochromic layers 12 and 14 may be two electrically conducting electrochromic nanocomposite layers or an electrochromic nanocomposite layer and an electrochromic inherently conducting polymer (ICP) layer.
  • ICP electrochromic inherently conducting polymer
  • the nanocomposite may be selected from one of the polymeric nanocomposites discussed above such as PAn/PMAS or PAn/PMAS/CNT.
  • the ICP layer may be selected from the group consisting of polythiophenes, polypyrroles, polyanilines, polyindoles, polycarbazoles, polyphenylene sulphide and polyparaphenylene and derivatives thereof . It is an option that the compounds chosen from these groups be substituted with at least one chemical functionality.
  • the ICP may comprise copolymers, block copolymers or graft copolymers each of which may include one or more different monomers or oligomers selected from the abovementioned groups. For example, there may be a sequence of thiophene units followed by a sequence of indole or pyrrole units, etc.
  • electrochromic layer 12 is cathodically colouring and formed from polyethylenedioxy-thiophene (PEDOT) doped with polystyrene sulfonic acid (PSS) .
  • PEDOT has a low redox potential, is stable to multiple redox switching and has a high conductivity. These properties are attributed to the high electron density of the molecular structure.
  • Other cathodically colouring electrochromes which can be used include polypropylenedioxy-thiophenes (PRODOT) .
  • Electrochromic layer 14 is anodically colouring and formed from a nanocomposite material. Preferably this is PAn/PMAS and even more preferably it is PAn/PMAS/CNT. Other examples are presented above.
  • the electrochromic layers are typically laid over the electrode layers . Multiple layers of the same electrochromic material may be laid. Referring to Figure
  • Electrodes 22 and 24 are transparent indium tin oxide (ITO) , however any suitable substantially transparent electrode could be used, for example, fluorine doped tin oxide (FTO), antimony doped tin oxide or other conductive metal oxides or thin metal films .
  • ITO indium tin oxide
  • FTO fluorine doped tin oxide
  • antimony doped tin oxide or other conductive metal oxides or thin metal films .
  • suitable electrochromic compositions may also act as electrodes, thereby avoiding the need for a specific electrode layer.
  • a nanocomposite layer incorporating ITO nanoparticles may be suitable.
  • the electrochromic layers and electrode layers are sandwiched between subtrates 32 and 34 which provide mechanical support and protection for the electrochromic layers.
  • Examples include poly (ethylene terephtalate) (PET), glass, plastics, metal foil, etc.
  • Busbars may also be added wires attached using conductive epoxy resin.
  • the device may be sealed using a suitable material such as an epoxy resin.
  • a method for constructing an electrochromic device is outlined in Figure 21 (200) .
  • a first conductive material is applied to a substrate layer to form a first electrode layer (202) .
  • a nanodispersion containing an electrically conducting electrochromic nanocomposite is applied to the first electrode layer so as to form a first electrochromic layer (204) .
  • a second electrochromic polymer is applied to the first electrochromic layer so as to form a second electrochromic layer (206) .
  • a second conductive material is applied to the second electrochromic layer so as to form a counter electrode layer (208) .
  • a protective layer may then be applied to the electrode layer (210) .
  • Busbars may also be added wires attached using conductive epoxy resin.
  • the device may be sealed using a suitable material such as an epoxy resin.
  • An electrochromic device may be constructed by building up successive layers .
  • a suitable substrate such as PET could be used (32) .
  • Electrode layer 22 could be laid followed by electrochromic layers 12, then 14, followed by electrode layer 24 and protective layer 34. These layers could be produced using known printing methods such as ink-jet, roll/press printing, silk screening or airbrushing; contact methods such as dip coating or spin coating.
  • first component comprising first substrate, electrode and electrochromic layers
  • second component comprising a second substrate, electrode and electrochromic layers
  • performance additives be added to the nanocomposite or ICP layer (or to other parts of the assembly) to improve the deposition process of the electrochromic layer.
  • a wetting agent such as a non-ionic surfactant
  • performance additives include-, preservation additives, rheological additives and/or antifoaming agents which can also be advantageously used to improve the adherence, UV stability, consistency, longevity, flexibility or deposition of the electrochromic layers .
  • the electrodes abut the electrochromic layer (except where they are combined) and the electrochromic layer covers at least a part of the electrode.
  • first sheet 32 and second sheet 24 which may be formed from plastic (PET) or glass or the like ( Figure 17b) .
  • the supports can then be pressed together and sealed (eg using Epoxy Resin) to thereby form an electrochromic device of Figure 17a.
  • the electrochromic device further requires the inclusion of a reflective surface.
  • the electrochromic assembly can abut a reflective surface (eg 30 in Figure 17c) or the electrode 22 or substrate 32 may be a reflective surface.
  • At least one of the supports has a reflective surface 30. It is an option that reflective surface 30 serve as an electrode, for example, electrode 22.
  • Incident light reflected by the assembly is shown by the arrow is shown in figure 17c.
  • the electrochromic device is optically transparent, an optical transmission path being formed between the electrodes and the reflective surface.
  • the arrow in Figure 17c shows that incident light which enters the electrochromic device passes through the optically transparent outer layer (34) , though counter- electrode layer 24 , then electrochromic layers 14 and 12 , and then through electrode layer 22 where it is reflected from reflective surface 30.
  • the electrochromic layers are not substantially interfering with the light path.
  • a conducting layer of particles preferably, nanoparticles, between the electrochromic layers and electrode layers so as to enhance the electrical contact between them.
  • the nanocomposite and/or ICP layers may act as electrodes, thereby negating the need for layers 22 and 24 as shown in Figure 17d. This could be achieved through choice of nanoparticles and nanocomposites, or through further addition of conducting additives, preferably nanoparticles
  • the materials from which electrochromic devices incorporating nanocomposites of the present invention are not hazardous to health or the environment .
  • the distance between the electrodes in the present arrangement is uniformly maintained electrochromic layers disposed between the electrode.
  • the present arrangement therefore does not suffer to the same extent from the problems faced in LCD displays since external and internal stresses in the present arrangement do not substantially effect the uniformity of the electric fields in the electrochromic device since the spacing between the electrodes cannot be substantially changed.
  • the electrode and electrochromic layers are thin and can rely on the supporting nature of the substrate to support them, and therfore prevent distortion and loss of functionality from physical stress.
  • a means may be provided for returning the electrochromic assembly to the non-dimming condition in the event of electrical failure.
  • This means can be an electrical switch which applies the required voltage potential between the electrodes in order to provide a non-dimming condition.
  • This safety feature is particularly- useful in vehicle mirror systems where it is preferable that the vehicle mirror be in the non-dimmed state by default.
  • Electrochromic devices incorporating the nanocomposites of the present invention may be produced which can be switched between highly transmissive and highly absorptive states as a function of applied voltage potential.
  • the electrical and optical properties of such electrochromic devices will depend upon the choice of materials (including the nanocomposite) .
  • the electrical and optical properties may be further controlled through choice of drop spacing and the number of (identical) electrochromic layers (containing nanocomposites of the present invention) printed (see Example 2, Table 3 and Figure 13) .
  • Various means can be provided for controlling the potential applied to electrochromic device so as to provide various dimming and non-dimming conditions. This is particularly advantageous in a vehicle rear-view mirror where activation is required when headlights cause glare in the mirror.
  • a photoelectrical switching device in the form of a photodiode, phototransistor or photocell such as an LDR can be used as a control means input.
  • the control means can be activated to provide a potential across the electrodes .
  • Photovoltaic cells and power storage devices such as batteries may also be employed, for instance to provide self-powered dimmable mirrors .
  • Various other components and control means can also be used.
  • Complex electrochromic devices could also be constructed, for example a digital display element (100) comprising 7 individual strip elements in a figure ⁇ 8" arrangement as shown in figure 18.
  • Seven strips of PRODOT (122, 124, 126, 128, 130, 132, 134) are first patterned on to a sheet of ITO coated substrate (eg glass) forming a cathode (140) .
  • Seven identical strips of a nanocomposite of the present invention (102, 104, 106, 108, 110, 112, 114), preferably PAn/PMAS/CNT is printed onto a segmented second sheet of ITO coated substrate (eg glass) forming the anode (120) .
  • PAn/PMAS/CNT/ITO strips oppose the PRODOT strips (dotted lines in Figure 18) .
  • the PAn/PMAS/CNT layer is printed directly over the PRODOT layer and the second sheet of segmented ITO coated substrate is pressed onto this layer (the segmentation and strips opposing the PRODOT strips) .
  • One electrical contact is made with the cathode, and seven electrical contacts, are made with the anode, one contact for each ITO-coated glass plate segment. The edges of the device are then sealed using epoxy resin. Joint electrical contact for PRODOT and independent electrical contacts for PAn/PMAS/CNT are made by attaching metal wires using silver paint.
  • Nanocomposites and/or nanocomposite dispersions may be directly printed onto polymer substrates. This enables construction of devices using lamination and roll-to-roll processes.
  • Roll to roll processing involves providing two physically spaced rollers. A flexible substrate material is wound on the first roller, and the exposed end is then wound onto the second roller, thereby exposing a relatively short section of the substrate material. Further rollers or means are used to guide and maintain the tension of the exposed material so that it may be guided over region where material may be deposited by various means onto the substrate. Following the deposition process, the modified substrate is rolled onto the second reel for storage.
  • the roll of substrate may be several metres wide by many kilometre long.
  • a deposition means is an ink jet printer. Such a printer could be used to pattern an electronic or electrochromatic device onto the substrate which incorporates a polymeric nanocomposite of the present invention. Other suitable means are also possible.
  • An inkjet printer, or other suitable means could be used for depositing other layers.
  • an electrode layer could be printed onto a poly (ethylene terephtalate) (PET) substrate.
  • PET poly (ethylene terephtalate)
  • a nanocomposite dispersion such as PAn/PMAS/CNT could then be printed over the PET substrate.
  • Multiple layers, electrode layers or protective layers could then be printed over the top .
  • Such devices could be sealed and then the patterned substrate rolled onto the second roller where it may be stored.
  • This roll may then be transported or used in a large scale manufacturing of devices incorporating the electronic or electrochromic device.
  • This type of storage method with its easy access to the patterned device offers a significant cost and time advantage from a manufacturing perspective since the rolls can be easily delivered and do not require substantial modification prior to use.
  • the roll could contain individual portions or complete devices, or laminar sheets. Portions of the patterned devices may be cut from the roll and used during manufacture. Portions of desired size and shape could be cut from laminar sheets and incorporated to make a desired device .
  • Roll-to-roll processing could be used to make components which are brought together at the time of manufacturing of the final device. For example rolls with the two components in figure 17b could be produced and stored separately and then pressed together at the time of manufacture.
  • the ability to print nanodispersions using inkjet printing more generally facilitates the production of a variety of electrical and electrochromic devices of varying sizes and shapes.
  • Choice of a flexible substrate would for example allow production of a curved electrochromic dimming mirror.
  • the pH of monomer and polymer solutions was measured using a TPS Instruments Model 900-P pH meter.
  • the synthesised nanodispersed materials were separated from the synthesis solution using a Beckman (J2-MC, rotor JAlO) centrifuge.
  • Reverse phase HPLC with a Waters Bondapak C18 column and a Linear UVIS 200 UV recorder ( ⁇ max 258 nm) was used to determine residual aniline. UV-vis spectra were recorded using a Shimadzu UV-1601 spectrophotometer. Cyclic voltammetry (CV) was carried out in a three electrode cell using a glassy carbon working electrode with platinum mesh auxiliary and Ag/AgCl (3M NaCl) reference electrodes using an E-Corder 401 interface and Potentiostat (EDAQ) . Conductivity measurements were performed on dried films of about 10 ⁇ m thickness drop cast onto glass slides from 5% w/v dispersion solutions using a JANDEL four-point probe resistivity system (model RM2) .
  • PMAS was chemically synthesised by polymerisation of MAS in the presence of ammonium persulfate as oxidant.
  • PMAS was synthesised under similar conditions reported previously2 using 0.025 mol (5g) MAS dissolved in 50 mL water, adding approximately 1.5 mL NH3 (28% w/w) slowly to pH 4.
  • 0.031 mol (7.14 g) (NH4) 2 S 2 O 8 (APS) dissolved in 25 mL
  • water was added dropwise to the monomer solution over 30 min at 5-10 °C. The reaction mixture was stirred overnight at the same temperature to complete the reaction.
  • the polymer was purified by a tangential flow diafiltration system using the procedure developed previously. 2
  • the dispersion was diluted six times in water and purified using a centrifuge at 4100 rpm for 15 min. The precipitate was then redispersed in water. The centrifugation/redispersion cycle was repeated 3 times until a pH of about 4 was obtained in the supernatant. UV-vis spectra obtained for the supernatant after filtering (0.2 ⁇ m) to remove any particulate interferences . PAn/HCl dispersion was prepared under identical conditions but in the absence of PMAS.
  • the UV-vis spectra of PAn/PMAS, PMAS and HCl doped polyaniline dispersions were obtained ( Figure IA) .
  • the spectrum of PAn/HCl exhibited broad bands at ca. 330-440 nm and a broad palaron peak centred at 755 nm, consistent with a compact coil-like conformation for polyaniline.
  • the spectrum of PMAS showed a band at 330 nm, attributed to ⁇ - ⁇ * transitions, and a sharp peak at 474 nm assigned as the lower wavelength polaron band.
  • the broad absorption at wavelengths longer than 700 nm have been attributed to a delocalized polaron transition, with the presence of the latter peak suggesting an extended coil- like conformation for PMAS.
  • the PMAS template forces its own backbone conformation on the nascent (forming) polyaniline due to the anilinium cation associating with the sulfonates moieties of the PMAS prior to polymerisation.
  • the resultant material was conformationally trapped, thereby attaining the observed spectral aspects of PMAS .
  • PAn/HCl C I4 H H N 2 CI dimer unit
  • the elemental analysis was: C 58.4, H 5.0, N 11.0, Cl 5.5.
  • a low doping level of 0.2 was estimated for the PAn/HCl material.
  • Elemental analysis of PAn/PMAS was: C 44.65, H 3.8, N 8.0, S 10.2, Cl 0.4.
  • the ratio of PMAS to PAn was estimated to be 1.5. This analysis assumes that no free SO 4 2" from the reduced APS was present in the purified composited after the repeated and rigerous washing and UV- vis analysis of the supernantant .
  • Nanofibres of polyaniline having diameters between 30 - 50 nm and lengths varying from 500 nm to several micrometers have been obtained from interfacial polymeriation or rapidly mixing the reagents , l ⁇ 9t12 TEM images were obtained by drop casting PAn/HCl or PAn/PMAS onto grids from dilute dispersions, Figure 3. Nanofibrillar structures with diameters of 50-80 nm were obtained for both PAn/HCl and PAn/PMAS. However, the polymerisation of aniline in the presence of PMAS resulted in the additional formation of spherical nanoparticles having diameters between 20 and 100 nm.
  • a dilute aqueous dispersion of PAn/HCl nanofibres prepared by the above method was only stable for 3-5 hours.
  • Pan/HCl and Pan/PMAS composite were drop cast onto separate glassy carbon electrodes, forming insoluble coatings after air drying over a day. Cyclic voltammetry studies were then carried out on the resultant films ( Figure 2) . Two typical redox couples [A 1 ZA 1 ' and B x /B"i) with anodic peaks at 0.37 V and 0.86 V (vs Ag/AgCl) were obtained for the Pan/HCl film.
  • PMAS is a water-soluble derivative of polyaniline which itself shows electroactivity either in solution 2 or in composite films resulting from complexation with other materials.
  • the second redox couple (B 2 /B' 2 ) was attributed to the interconversion of emeraldine to the pernigraniline state of PMAS. [15 ' 1S]
  • the third redox pair (C 2 /C 2 ) was assigned to the transformation of the Pan emeraldine state to the pernigraniline form.
  • PMAS was present the observed redox couples were more clearly defined with respect to the ,Pan/HCl films prepared under equivalent conditions. It is hypothesised that this enhancement may be as a result of the more conductive nature of the nanocomposites , as discussed below.
  • Electroactive PAn/PMAS nanoparticles with very high dispersion stability and high conductivity have been prepared with well defined nanofibres and nanoparticles of diameters between 20 and 100 nm, as observed by TEM.
  • the UV-vis spectra of the PAn/PMAS composite in water and in alkaline media confirm the presence of both PAn and PMAS in the nanocomposite.
  • the high S/Cl molar ratio obtained from elemental analysis and the high conductivity of the composite indicate that PMAS is the dominant dopant.
  • the ratio of PMAS to PAn is 1.5, indicating that there is sufficient PMAS to dope the PAn in the emeraldine state, with excess sulfonate groups providing a stabilising effect in the resultant dispersion.
  • MWNTs were dispersed in PMAS using ultrasonic treatment.
  • Solution of PMAS at concentration ⁇ 1 mg/ml were sonicated with a Branson Digital Ultrasonic Sonifier 450 D (400 W, 3 mm tapered microtip) for 2, 5, 10, 30 and 60 mins at 16W in pulsed mode (2s on, Is off) .
  • the final aniline-to-APS molar ratio was 4:1, while the MWNT: aniline weight ratios were 0.1, 0.2, 0.4, 0.6, 1.35 and 2.7. (loading fractions of 3.4%, 6.6%, 12.4%, 17.5%, 32% and 64 % of MWNT in PMAS respectively) .
  • the dispersion was diluted six times in water and purified using a centrifuge at 4100 rpm for 15 min. The precipitate was then redispersed in water. The centrifugation/redispersion cycle was repeated 3 times until a pH of about 4 was obtained in the supernatant.
  • PMAS functions in a dual role as a nanotube stabilizer and as a molecular dopant during aniline polymerisation which results in the formation of PAn/PMAS-MWNT composites.
  • the MWNT loading fraction is calculated as follows . Carbon nanotubes are stabilized in 80 mg PMAS for MWNT: aniline weight ratios 0.1, 0.2, 0.4, 0.6, 1.35 and 2.7. Hence a MWNT: aniline weight ratio of 0.1 corresponds to a MWNT loading fraction of 3.4%, e.g. 3.75 mg MWNT in ⁇ 110 mg polymeric material. (It was found that 70% of aniline starting amount (37mg) is consumed during polymerisation. ) Structure
  • FIG. 10 A TEM image of an evaporated dispersion of a Pan/PMAS-MWNT dispersion is shown in Figure 10. 1 (PAn) : 2.2 (PMAS) : 1.7 (CNT) ] .
  • Sheet resistance and electrical conductivity Film thickness of free standing films prepared by drop casting was determined by Mitutoyo digital micrometer. Conductivity measurements (Table 2) were carried out using a JANDEL four-point probe resistivity system (model RM2) .
  • Thermogravimetrix analysis shows that the polymers decomposition pattern is augmented by a nanotube decomposition step, which increases with loading fraction.
  • optical and electrical properties of highly conducting but light absorbing materials such as carbon nanotube are affected by the amount of nanotubes deposited as demonstrated using line patterning. Increasing the concentration reduces both R 3 (more electrical pathways) and transmittance [T, more light absorbed) . This is demonstrated by increasing the number of printed layers, the MWNT loading fraction and spacing between deposited drops. Figure 13 shows that increasing the number of prints to 3 improves the electrical sheet resistance by a factor 2.5, at a cost of 20% in optical transparency.
  • Nanotube dispersions (concentration 10mg/ml, temperature 25 0 C, viscosity 5.5 CP, and surface tension 72 mN/m) were inkjet printed using a Dimatrix materials deposition system (Fuji film Dimatrix) . Patterns were deposited onto flexible transparent poly (ethylene terephtalate) (PET) , Hewlett-Packard glossy photo paper, Platinized indium tin oxide coated glass (Pt-ITO) , and gold coated poly (vinylidene fluoride) (Au-PVDF) (see Figure 13) for examples .
  • PET flexible transparent poly
  • Pt-ITO Platinized indium tin oxide coated glass
  • Au-PVDF gold coated poly (vinylidene fluoride)
  • PAn/PMAS/CNT electrode was tested with a standard ProDOT coating on the opposing electrode in an electrochromic device.
  • PAn/PMAS vs ProDOT, PMAS and PMAS/Prussian Blue electrodes were also produced and tested.
  • the transmissitivity of the electrode combinations were studied in the forward and reverse potential states .
  • the PMAS based electrodes were deposited by spin-coating, with the aim to deposit approximately enough materials to produce an initial absorbance of circa 70% T for the PMAS electrode by itself.
  • Panels A through D of Figure 16 illustrate the difference in transmissitivity (T) as a function of wavelength of each electrode combination when in the forward and reverse potential states.
  • the PAn/PMAS/CNT electrode (with a 6% loading of CNT used in combination with a ProDOT electrode produced highly desirable spectral qualities, dipping in transmission around the 550nm region on darkening, where the human eye is most sensitive (Panel A of Figure 16) .
  • PAn/PMAS/CNT the change in transmittance range at 550nm was approximately 47% (67% down to 20%) . This is compared to a 42% change in transmittance for PAn/PMAS (Panel B) , 38% for PMAS (Panel C) and 20% for PMAS/Prussian Blue (Panel D) .

Abstract

L'invention concerne un nanocomposite polymère électriquement conducteur comprenant un premier polymère conducteur et un second polymère conducteur qui joue le rôle d'un dopant du premier polymère conducteur. L'invention concerne également un procédé permettant de préparer le nanocomposite polymère et son utilisation dans des dispositifs optiques et électrochimiques, y compris des dispositifs électrochromes. Par exemple, le nanocomposite polymère peut se trouver sous forme d'une nanodispersion qui peut être imprimée avec une imprimante à jet d'encre permettant la fabrication de dispositifs électroactifs et électrochromes par des méthodes de traitement bobine à bobine.
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