WO2008075009A1

WO2008075009A1 - Composite material

Info

Publication number: WO2008075009A1
Application number: PCT/GB2007/004824
Authority: WO
Inventors: Adam Chaplin; Brian Wilson; Alan Wood
Original assignee: Victrex Manufacturing Limited
Priority date: 2006-12-21
Filing date: 2007-12-17
Publication date: 2008-06-26
Also published as: GB0625484D0; TW200844120A

Abstract

A process for preparing a composite material which comprises a polymeric material, for example a polyaryletherketone, and nanoparticles, the process comprising dispersing nanoparticles in a fluid to prepare a nanoparticles dispersion in said fluid; contacting the dispersion with one or more monomers to prepare a mixture comprising nanoparticles and one or more monomers; and polymerising the monomers to produce a composite material comprising nanoparticles dispersed in the polymeric material which is formed.

Description

COMPOSITE MATERIAL

This invention relates to a composite material and particularly, although not exclusively, relates to a process for preparing a composite material which incorporates nanoparticles, for example fullerenes, in the form of, for example, nanotubes.

Fullerenes are molecular carbon species having at least 60 carbon atoms. Example of fullerenes include carbon nanotubes (SWNTs) and multi-walled carbon nanotubes

(MWNTs) . SWNTs include hollow molecules of pure carbon linked together in a hexagonally bonded network to form a hollow cylinder. The tubes are seamless with open or capped ends . The diameter of SWNTs is usually in the range 0.7 to 2nm and typically approximately lnm.

Composite materials which comprise thermoplastic polymers and carbon nanotubes have been proposed. For example, WO98/39250 describes in claim 122 a composite material which comprises a thermoplastic polymer in which a carbon nanotube material is embedded. Polyetheretherketone is referenced in a list of 12 polymer types. However, no details are included on how a composite of, for example, polyetheretherketone and carbon nanotubes may be prepared.

SWNTs and MWNTs (and other nanoparticles) often have a high aspect ratio and tend to stick to one another, which makes it difficult to disperse them in polyetheretherketone and/or difficult to provide composite materials with a high loading of such materials. It is an object of the present invention to address the above described problems.

According to a first aspect of the present invention, there is provided a process for preparing a composite material which comprises a polymeric material and nanoparticles, wherein the polymeric material is of a type which includes:

a) phenyl moieties; b) ketone and/or sulphone moieties; and c) ether and/or thioether moieties;

the process comprising the steps of:

(i) dispersing nanoparticles in a fluid to prepare a nanoparticles dispersion of nanoparticles in said fluid;

(ii) contacting the dispersion prepared in (i) with one or more monomers thereby to prepare a mixture comprising nanoparticles and one or more monomers wherein said one or more monomers is/are polymerisable to produce said polymeric material; (iii) polymerising the mixture prepared in (ii) to produce a composite material comprising nanoparticles dispersed in said polymeric material .

Nanoparticles may suitably be in accordance with the definition in PAS71 (issued by BSI, UK) which describes a nanoparticle as a particle having one or more dimensions of the order of lOOnm or less. Thus, nanoparticles described herein suitably have dimensions of less than lOOnm. In some embodiments, the nanoparticles may have dimensions of less than 50nm or even less than IOnm.

Said nanoparticles may be any type of such particles. They may be organic, inorganic or metals. Examples of nanoparticles include VGCF (Vapour Grown Carbon Fibre) , Zinc Silicate nanoparticles, Nano diamonds, Nano silicon, Nano metals (e.g. gold, iron oxide), Carbon nanotubes (single and multi walled), Fullerite, Fullerenes, Carbon Buckyballs/Buckypaper, Carbon nanotorus, Nano ceramic particles, Titanium dioxide nanoparticles, Endohedral fullerenes, Alumina nanoparticles, Magnetic materials such as Barium ferrite nanoparticles, Polymeric nanoparticles, Hydroxyaptite nanoparticles.

Said composite material may comprise a said polymeric material which defines a matrix and additional material distributed within the matrix wherein a major amount of said additional material is comprised of said nanoparticles.

When said nanoparticles comprise fullerene moieties, said fullerene moieties suitably include a major amount of carbon nanotubes. Said carbon nanotubes may be SWNTs or MWNTs. Said fullerene moieties preferably comprise or, more preferably, consist essentially of SWNTs.

Unless otherwise specified herein, where reference is made to a material include a "major amount" of a component, the specified component may be present at level of at least 60wt%, suitably at least 70wt%, preferably at least 80wt%, more preferably at least 90wt%, especially at least 95wt% of the total weight of the material and, preferably, the material consists essentially of the specified component.

In the method, at least 0.05 wt% of nanoparticles, suitably at least 0.10wt%, preferably at least 0.15wt%, more preferably at least 0.20wt%, especially at least 0.25wt% of nanoparticles may be dispersed in said dispersion. The dispersion may include less than 2wt%, suitably less than lwt%, preferably less than 0.6wt%, more preferably less than 0.4wt%, especially 0.3wt% or less of nanoparticles. Preferably, at least 0.15wt% and less than 0.4wt% of nanoparticles are dispersed in said dispersion. The ratio of the weight of nanoparticles to the weight of fluid in said dispersion prepared in step (i) may be in the range 0.0015 to 0.0035, especially in the range 0.002 to 0.004.

Said fluid preferably comprises a major amount of an organic material which may have a melting point of at least 0⁰C, suitably of at least 15°C, preferably at least 40⁰C, more preferably of at least 80⁰C, especially at least 100⁰C. The melting point is suitably less than 300⁰C, preferably less than 25O⁰C, more preferably less than 200⁰C, especially less than 150⁰C. Said organic material may have a boiling point of less than 500⁰C, preferably less than 400°C. The boiling point may be greater than HO⁰C, preferably greater than 200⁰C.

Preferably, said fluid acts as a polymerisation solvent in step (ii) of the process - i.e. a solvent in which said one or more monomers used in step (ii) are dissolved or dispersed. Suitably, said fluid represents at least 50wt%, preferably at least 65wt%, more preferably at least 80wt%, especially at least 95wt% of the total wt% of solvent used in step (ii) . In the most preferred embodiment, said fluid in which the nanoparticles are dispersed in step (i) provides substantially the entirety of the solvent present during the polymerisation reaction of step ii) .

The identity of the fluid used in step (i) will depend on the identity of the one or more monomers and on details of the polymerisation reaction of step (iii) . Preferably, said fluid is a polar organic solvent.

Preferably, in step (i) , the nanoparticles are contacted with said fluid and then dispersed. The step preferably includes directing an oscillating energy source into the fluid. The step preferably uses ultrasound to sonicate the nanoparticles in said fluid and disperse them therein. Energy is preferably applied in step (i) for at least 30 minutes, preferably at least 1 hour, preferably at least 1.5 hours.

Step (i) may be carried out at a temperature greater than ambient temperature. Step (i) is preferably carried out at a temperature of less (preferably at least 5O⁰C less) than the boiling point of the fluid, with the fluid in the liquid state. The fluid may be maintained at the temperature for at least 0.5 hours, preferably at least 1 hour.

After the nanoparticles have been dispersed as described in step (i) , the dispersion may be cooled or allowed to cool, suitably to ambient temperature, in order to solidly said fluid with said nanoparticles dispersed therein. This may allow the dispersion to be easily stored prior to subsequent use. Alternatively, said dispersion may be used directly after step (i) without any intermediate solidification step.

Except where otherwise stated throughout this specification, any alkyl, akenyl or alkynyl moiety suitably has up to 8, preferably up to 6, more preferably up to 4, especially up to 2, carbon atoms and may be of straight chain or, where possible, of branched chain structure. Generally, methyl and ethyl are preferred alkyl groups and C₂ alkenyl and alkynyl groups are preferred.

Except where otherwise stated in this specification, optional substituents of an alkyl group may include halogen atoms, for example fluorine, chlorine, bromine and iodine atoms, and nitro, cyano, alkoxy, hydroxy, amino, alkylamino, sulphinyl, alkylsulphinyl, sulphonyl, alkylsulphonyl, amido, alkylamido, alkoxycarbonyl, haloalkoxycarbonyl and haloalkyl groups. Preferably, optionally substituted alkyl groups are unsubstituted.

Preferably, said polymeric material has a moiety of formula

and/or a moiety of formula

and/or a moiety of formula

wherein the phenyl moieties in units I, II, and III are independently optionally substituted and optionally cross- linked; and wherein m,r,s,t,v,w and z independently represent zero or a positive integer, E and E' independently represent an oxygen or a sulphur atom or a direct link, G represents an oxygen or sulphur atom, a direct link or a -O-Ph-0- moiety where Ph represents a phenyl group and Ar is selected from one of the following moieties (i) *, (i)**, (i) to (x) which is bonded via one or more of its phenyl moieties to adjacent moieties

or

Unless otherwise stated in this specification, a phenyl moiety may have 1,4- or 1,3-, especially 1,4-, linkages to moieties to which it is bonded.

In (i)*, the middle phenyl may be 1,4- or 1, 3-substituted.

Said polymeric material may include more than one different type of repeat unit of formula I; more than one different type of repeat unit of formula II; and more than one different type of repeat unit of formula III. Preferably, however, only one type of repeat unit of formula I, II and/or III is provided.

Said moieties I, II and III are suitably repeat units. In the polymeric material, units I, II and/or III are suitably bonded to one another - that is, with no other atoms or groups being bonded between units I, II, and III.

Where the phenyl moieties in units I, II or III are optionally substituted, they may be optionally substituted by one or more halogen, especially fluorine and chlorine, atoms or alkyl, cycloalkyl or phenyl groups. Preferred alkyl groups are Ci-io, especially C₁-.₄, alkyl groups.

Preferred cycloalkyl groups include cyclohexyl and multicyclic groups, for example adamantyl.

Another group of optional substituents of the phenyl moieties in units I, II or III include alkyls, halogens, C_yF2y₊i where y is an integer greater than zero, O-R^q (where R^q is selected from the group consisting of alkyls, perfluoralkyls and aryls), CF=CF₂, CN, NO₂ and OH. Trifluormethylated phenyl moieties may be preferred in some circumstances .

Preferably, said phenyl moieties are not optionally- substituted as described.

Where said polymeric material is cross-linked, it is suitably cross-linked so as to improve its properties. Any suitable means may be used to effect cross-linking. For example, where E represents a sulphur atom, cross-linking between polymer chains may be effected via sulphur atoms on respective chains. Preferably, said polymeric material is not optionally cross-linked as described.

Where w and/or z is/are greater than zero, the respective phenylene moieties may independently have 1,4- or 1,3- linkages to the other moieties in the repeat units of formulae II and/or III. Preferably, said phenylene moieties have 1,4- linkages.

Preferably, the polymeric chain of the polymeric material does not include a -S- moiety. Preferably, G represents a direct link.

Suitably, "a" represents the mole % of units of formula I in said polymeric material, suitably wherein each unit I is the same; "b" represents the mole % of units of formula II in said polymeric material, suitably wherein each unit II is the same; and "c" represents the mole % of units of formula III in said polymeric material, suitably wherein each unit III is the same. Preferably, a is in the range 45-100, more preferably in the range 45-55, especially in the range 48-52. Preferably, the sum of b and c is in the range 0-55, more preferably in the range 45-55, especially in the range 48-52. Preferably, the ratio of a to the sum of b and c is in the range 0.9 to 1.1 and, more preferably, is about 1. Suitably, the sum of a, b and c is at least 90, preferably at least 95, more preferably at least 99, especially about 100. Preferably, said polymeric material consists essentially of moieties I, II and/or III.

Said polymeric material may be a homopolymer having a repeat unit of general formula

or a homopolymer having a repeat unit of general formula

or a random or block copolymer of at least two different units of IV and/or V

wherein A, B, C and D independently represent 0 or 1 and E, E ' , G, Ar,m, r, s, t, v, w and z are as described in any statement herein.

As an alternative to a polymeric material comprising units IV and/or V discussed above, said polymeric material may be a homopolymer having a repeat unit of general formula

or a homopolymer having a repeat unit of general formula

or a random or block copolymer of at least two different units of IV* and/or V*, wherein A, B, C, and D independently represent 0 or 1 and E, E', G, Ar, m, r, s, t, v, w and z are as described in any statement herein.

Preferably, m is in the range 0-3, more preferably 0-2, especially 0-1. Preferably, r is in the range 0-3, more preferably 0-2, especially 0-1. Preferably t is in the range 0-3, more preferably 0-2, especially 0-1. Preferably, s is 0 or 1. Preferably v is 0 or 1. Preferably, w is 0 or 1. Preferably 2 is 0 or 1.

Preferably, said polymeric material is a homopolymer having a repeat unit of general formula IV.

Preferably Ar is selected from the following moieties (xi)*, (xi)**,(xi) to (xxi) :

(xi)^**

In (xi)*, the middle phenyl may be 1,4- or 1,3- substituted. Preferably, (xv) is selected from a 1,2-, 1,3-, or a 1,5- moiety; (xvi) is selected from a 1,6-, 2,3-, 2,6- or a 2,7- moiety; and (xvii) is selected from a 1,2-, 1,4-, 1,5-, 1,8- or a 2,6- moiety.

One preferred class of polymeric 'material does not include any moieties of formula III, but suitably only includes moieties of formulae I and/or II. Where said polymeric material is a homopolymer or random or block copolymer as described, said homopolymer or copolymer suitably includes a repeat unit of general formula IV. Such a polymeric material may, in some embodiments, not include any repeat unit of general formula V.

Suitable moieties Ar are moieties (i)*, (i) , (ϋ), (iii) and (iv) and, of these, moieties (i)*, (i) and (iv) are preferred. Other preferred moieties Ar are moieties (xi)*, (xii), (xi) , (xiii) and (xiv) and, of these, moieties (xi) *, (xi) and (xiv) are especially preferred.

An especially preferred class of polymeric material are polymers (or copolymers) which consist essentially of phenyl moieties in conjunction with ketone and/or ether moieties. That is, in the preferred class, the polymeric material does not include repeat units which include -S-, - SO2- or aromatic groups other than phenyl. Preferred polymeric materials of the type described include:

(a) a polymer consisting essentially of units of formula IV wherein Ar represents moiety (iv) , E and E' represent oxygen atoms, m represents 0, w represents 1, G represents a direct link, s represents 0, and A and B represent 1 (i.e. polyetheretherketone) .

(b) a polymer consisting essentially of units of formula IV wherein E represents an oxygen atom, E' represents a direct link, Ar represents a moiety of structure (i) , m represents 0, A represents 1,

B represents 0 (i.e. polyetherketone) ;

(c) a polymer consisting essentially of units of formula IV wherein E represents an oxygen atom, Ar represents moiety (i)*, m represents 0, E' represents a direct link, A represents 1, B represents 0, (i.e. polyetherketoneketone) .

(d) a polymer consisting essentially of units of formula IV wherein Ar represents moiety (i) , E and E' represent oxygen atoms, G represents a direct link, m represents 0, w represents 1, r represents 0, s represents 1 and A and B represent 1. (i.e. polyetherketoneetherketoneketone) .

(e) a polymer consisting essentially of units of formula IV, wherein Ar represents moiety (iv) , E and E' represents oxygen atoms, G represents a direct link, m represents 0, w represents 0, s, r, A .and B represent 1 (i.e. polyetheretherketoneketone) .

(f) a polymer consisting essentially of units of formula IV, wherein E represents an oxygen atom, E' represents a direct link, Ar represents a moiety of structure (ii) , m represents 0, A represents 1, B represents 0 (i.e. polyethersulphone) .

(g) a polymer consisting essentially of units of formula V, wherein E and E' represent oxygen atoms, Ar represents moiety (xi)**, m represents 0, z represents 1, G represents a direct link, v represents 0, C and D represent 1 (i.e. polysulphone) .

Said polymeric material is preferably semi-crystalline. The level and extent of crystallinity in a polymer is preferably measured by wide angle X-ray diffraction (also referred to as Wide Angle X-ray Scattering or WAXS) , for example as described by Blundell and Osborn (Polymer 24 , 953, 1983) . Alternatively, crystallinity may be assessed by Differential Scanning Calerimetry (DSC) .

The level of crystallinity in said polymeric material may be at least 1%, suitably at least 3%, preferably at least 5% and more preferably at least 10%. In especially preferred embodiments, the crystallinity may be greater than 30%, more preferably 40%, especially 45%.

The glass transition temperature (T_g) of said polymeric material may be at least 140⁰C.

Said polymeric material may have an inherent viscosity (IV) of at least 0.1, suitably at least 0.3, preferably at least 0.4, more preferably at least 0.6, especially at least 0.7

(which corresponds to a reduced viscosity (RV) of least

0.8) wherein RV is measured at 25⁰C on a solution of the polymer in concentrated sulphuric acid of density 1.84gcrrf³, said solution containing Ig of polymer per lOOcirf³ of solution. IV is measured at 25°C on a solution of polymer in concentrated sulphuric acid of density 1.84gcm³, said solution containing 0. Ig of polymer per 100cm³ of solution.

The measurements of both RV and IV both suitably employ a viscometer having a solvent flow time of approximately 2 minutes .

The main peak of the melting endotherm (Tm) for said polymeric material (if crystalline) may be at least 300⁰C.

In preferred embodiments, said polymeric material is selected from polyetheretherketone and polyetherketone. In an especially preferred embodiment, said polymeric material is polyetheretherketone.

Said one or more monomers may be adapted to produce said polymeric material via an electrophilic or nucleophilic process. Examples of electrophilic processes are described in EP1170318 (Gharda) and the content of the aforementioned document as regards the polymer preparation process described is incorporated herein by reference. The aforementioned document describes self-condensation reactions of a single monomer.

Examples of nucleophilic processes are described in EP1879 (ICI) and the contents of the aforementioned document as regards the process are incorporated herein by reference.

Said fluid used in step (i) may be an aromatic sulphone, an optionally-substituted alkane or aryl sulphonic acid, HF, a fluorocarbon solvent or sulfolane. A said aromatic sulphone may be of formula

wherein R⁵¹ is a direct link, an oxygen atom or two hydrogen atoms (are attached to each benzene ring) and R⁵⁰ and R⁵² are, independently, hydrogen atoms or phenyl groups. Examples of sulphones include diphenylsulphone, dibenzothiophen dioxide, phenoxathiin dioxide, and 4- phenylsulphonyl biphenyl . Diphenyl sulphone is preferred. A said alkane or aryl sulphonic acid may be an optionally- substituted Ci-₂ sulphonic acid ■ or optionally-substituted benzene sulphonic acid. A said optionally-substituted acid may be halogenated especially with chlorine or fluorine atoms. Examples of the aforesaid include methane sulphonic acid, trifluoromethane sulphonic acid and trichloromethane sulphonic acid.

Said fluid is preferably selected from an aromatic sulphone, especially diphenyl sulphone and an optionally- fluorinated or chlorinated methane sulphonic acid, with unsubstituted methane sulphonic acid being preferred.

Preferably, a said aromatic sulphone is used as a solvent in a nucleophilic process and a said methane sulphonic acid is used in an electrophilic process .

Polymers having units I, II, III, IV, IV*, V and/or V* may be prepared by: (a) polycondensing a compound of general formula

with itself wherein Y¹ represents a halogen atom or a group -EH and Y² represents a halogen atom or, if Y¹ represents a halogen atom, Y² represents a group E¹H; or

(b) polycondensing a compound of general formula

with a compound of formula

and/or with a compound of formula

wherein Y¹ represents a halogen atom or a group -EH (or - E¹H if appropriate) and X¹ represents the other one of a halogen atom or group -EH (or -E¹H if appropriate) and Y² represents a halogen atom or a group -E¹H and X² represents the other one of a halogen atom or a group -E¹H (or -EH if appropriate) .

(c) optionally copolymerizing a product of a process as described in paragraph (a) with a product of a process as described in paragraph (b) ;

wherein the phenyl moieties of units VI, VII and/or VIII are optionally substituted; and Ar, m, w, r, s, z, t, v, G, E and E' are as described above except that E and E' do not represent a direct link;

the process also optionally comprising cross-linking a product of the reaction described in paragraphs (a) , (b) and/or (c) to prepare said polymer.

Preferably, where Y¹, Y², X¹ and/or X² represent a halogen, especially a fluorine, atom, an activating group, especially a carbonyl or sulphone group, is arranged ortho- or para- to the halogen atom.

Preferred halogen atoms are fluorine and chlorine atoms, with fluorine atoms being especially preferred. Preferably, halogen atoms are arranged meta- or para- to activating groups, especially carbonyl groups. Wherein the process described in paragraph (a) is carried out, preferably one of Y^α and Y² represents a fluorine atom and the other represents an hydroxy group. More preferably in this case, Y¹ represents a fluorine atom and Y² represents an hydroxy group. Advantageously, the process described in paragraph (a) may be used when Ar represents a moiety of structure (i) and m represents 1.

When a process described in paragraph (b) is carried out, preferably, Y¹ and Y² each represent an hydroxy group. Preferably, X¹ and X² each represent a halogen atom, suitably the same halogen atom.

Compounds of general formula VI, VII and VIII are commercially available (eg from Aldrich U. K) and/or may be prepared by standard techniques, generally involving

Friedel-Crafts reactions, followed by appropriate derivatisation of functional groups. The preparations of some of the monomers described herein are described in P M Hergenrother, B J Jensen and S J Havens, Polymer 2_9, 358

(1988), H R Kricheldorf and ϋ Delius, Macromolecules 2_2,

517 (1989) and P A Staniland, Bull, Soc, Chem, BeIg., ^8

(9-10), 667 (1989).

After preparation of said polymer, it is preferably isolated and solvent (s) used in the polycondensation removed so that the level of such solvents is less than 5 wt%, preferably less than lwt% of the level thereof during the polycondensation.

Preferably in step (ii) all of the monomers required to prepare said polymeric material are contacted with the dispersion prepared in step (i) in a receptacle. Whilst additional solvent may be added to facilitate the polymerisation, preferably a major amount of the total amount of solvent used in the polymerisation reaction is provided by the fluid present in the dispersion prepared in step (i) . In step (iii) , polymerisation of the mixture may be carried out at an elevated temperature, suitably with agitation.

In a preferred embodiment, step (ii) of the process involves contacting the dispersion prepared in step (i) with at least one bisphenol (e.g. hydroquinone) at least one aromatic dihalide (e.g. 4, 4' -difluorobenzophenone) , suitably in the presence of an alkali metal carbonate or bicarbonate and in the presence of a solvent which suitably is made up of a major amount of said fluid used to prepare said dispersion.

At the end of the polymerisation, the composite material prepared may be isolated by standard techniques. It may be formed into a powder or granules.

Said composite material may include at least 0.1 wt%, preferably at least 0.2wt%, more preferably at least 0.3wt% of nanoparticles for example fullerene moieties, especially SWNTs. Advantageously, the process of the first aspect may be used to make composite materials having up to 20wt% of nanoparticles, for example 1 to 20 wt%, preferably 2 to 5wt% of nanoparticles.

In one embodiment, said composite material may comprise a major amount of a single polymeric material all of which is suitably prepared in step (ii) . In another embodiment, said composite material may comprise polymeric material prepared in step (ii) and other polymeric material introduced into the composite material in another step. Thus, the process of the first aspect may include the optional step of contacting, in a step additional to step (ii) , a further polymeric material with said nanoparticles in order to form said composite material. In the optional step, the further polymeric material may be the same or different to the polymeric material prepared in step (ii) . Preferably, a major amount of polymeric material (s) in the composite comprises a said polymeric material prepared in step (ii) .

According to a second aspect of the invention, there is provided a process for preparing a second composite material which comprises a first polymeric material and x wt% of nanoparticles (eg nanotubes) , wherein x wt% refers to the wt% of nanoparticles in the second composite material, the process comprising:

i) selecting a first composite material comprising said first polymeric material and y wt% of nanoparticles, wherein y refers to the wt% of nanoparticles in the first composite material and wherein y is greater than x; ii) contacting said first composite material with further polymeric material in order to prepare said second composite material.

Said first polymeric material may be any of the polymeric materials described according to the first aspect. Said first polymeric material is preferably melt processible. Its degradation temperature is suitably higher than its melting point (suitably by at least 10°C, preferably by at least 2O⁰C) so that it can be extruded without significant degradation. Said first polymeric material is preferably a polyaryletherketone (especially selected from polyetheretherketone, polyetherketone and polyetherketoneketone) , a polyarylethersulphone

(especially polyethersulphone) or polysulphone. In the most preferred embodiment said first polymeric material is polyetheretherketone .

Said further polymeric material may be any of the polymeric materials described according to the first aspect. Said further polymeric material is preferably melt processible. Its degradation temperature is suitably higher than its melting point (suitably by at least 1O⁰C, preferably by at least 20⁰C) so that it can be extruded without significant degradation. Said further polymeric material may be selected from polyaryletherketones, polyarylether sulphones, polyetherimides and PBI provided the selected material is melt processible.

In one embodiment, said first polymeric material and said further polymeric material may be the same. For example, both may be polyetheretherketone. In this case, the process of the second aspect may be used to adjust the level of nanoparticles in the first composite material to a desired level. In another embodiment, said first and said further polymeric materials may be different. For example, said first polymeric material could be a polyaryletherketone, especially polyetheretherketone and said further polymeric material could be a polyetherimide.

Said second composite material may be prepared by melt processing said first and second polymeric materials together at a temperature in the range 300 to - 400⁰C, preferably in the range 340 to 400⁰C, more preferably in the range 340 to 380⁰C.

The difference between y and x may be at least 2wt%, more preferably at least 3wt%, especially at least 4wt%. The value for y may be less than 10wt%, preferably less than 8wt%, more preferably less than 6wt%, especially less than 5.5wt%.

x may be in the range 0.05 to lwt%, preferably in the range 0.1 to 0.5wt%.

In the process of the second aspect, the ratio of the weight of said first composite material to that of said further polymeric material contacted in step (ii) is suitably less than 1, is preferably less than 0.75 and more preferably is less than 0.5. The ratio may be at least 0.05, preferably at least 0.1.

In step (ii) said first composite material and further polymeric material are preferably contacted at an elevated temperature, suitably of greater than 50⁰C, preferably greater than 100⁰C, more preferably greater than 200⁰C, especially at greater than 300⁰C. The temperature preferably does not exceed 500⁰C, more preferably does not exceed 45O⁰C .during step (ii) .

Preferably, step (ii) includes the use of an extruder, for example a twin-screw extruder. Thus, step (ii) preferably involves subjecting said first composite material and said further polymeric material to an elevated temperature and high shear. The process of the second aspect may involve blending one or more fillers with the polymeric materials. Examples of fillers include fibrous fillers, such as inorganic fibrous materials such as glass fiber, asbestos fiber, silica fiber, alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber and potassium titanate fiber and high-melting organic fibrous materials such as polyamide, fluorocarbon resins, polyester resins and acrylic resins. Other fillers may be non-fibrous fillers such as mica, silica, talc, alumina, kaolin, calcium sulfate, calcium carbonate, titanium oxide, ferrite, clay, glass powder, zinc oxide, nickel carbonate, iron oxide, quartz powder, magnesium carbonate and barium sulfate. The non-fibrous fillers are generally in the form of powder or flaky particles .

Preferably, the process of the second aspect does not include incorporation of fillers.

The invention extends to a composite material prepared in the process of the first or second aspects.

The invention extends to a composite material comprising polyetheretherketone and at least 0.1 wt% of nanoparticles for example fullerene moieties.

Said composite material may include at least 0.5 wt%, preferably at least 1 wt%, more preferably 1 to 20 wt%, especially 1 to 5 wt% of nanoparticles.

The invention extends to a composite material comprising a first polymeric material (suitably as described above, preferably polyetheretherketone) , a further polymeric material (suitably as described above, preferably polyetherimide) and nanoparticles .

The composite materials described herein may be used for producing materials with improved thermal, electrical and wear characteristics. They may be used to produce materials with improved mechanical properties, surface finish, lower diffusion rates and improved recyclability.

Some composite materials described herein (e.g. which includes fullerene moieties) may be used in electrostatic discharge (ESD) or as anti-static applications. The invention extends to the use of a composite material described for electrostatic discharge or in an anti-static application. The invention extends to an ESD tube or ESD film for example for a photocopier or printer; a wafer carrier, for example a silicon wafer carrier; a chip carrier tray, for example a silicon chip carrier tray; or a test socket for example for testing silicon chips, incorporating a composite material as described herein.

Any feature of any aspect of any invention or embodiment described herein may be combined with any feature of any aspect of any other invention or embodiment described herein mutatis mutandis.

Specific embodiments of the invention will now be described by way of example.

The following are referred to hereinafter: SWNTs - refers to "single-walled nanotubes" obtained from Carbon Nanotechnologies Inc (CNI) of Houston, USA.

MWNTs - refers to "multi-walled carbon nanotubes" obtained from Hyperion Catalysis of Cambridge, USA.

BDF - refers to 4 , 4' -difluorobenzophenone .

Unless otherwise stated, all materials are available from and/or were used as received from Aldrich, UK.

Example 1 - Preparation of diphenylsulphone/SWNT dispersion

A jacketed glass reactor was charged with diphenyl sulphone (49g) and SWNTs (0.144g). The contents were heated to 140⁰C (eg using hot oil circulation) and sonicated in an ultrasonic bath for a period of 2 hours . The flask was then allowed to cool under sonication conditions, until the solvent had solidified. The contents were then allowed to cool further under ambient conditions .

Example 2 - Preparation of composite of polyetheretherketone and SWNTs

A 250ml flanged flask fitted with a -ground gl^~a^~ss Quickfit lid, stirrer/stirrer guide, nitrogen inlet and outlet was charged with 4, 4' -difluorobenzophenone (22.2βg, 0.102 mole), hydroquinone (ll.Olg, 0.1 mole) and the solid diphenylsulphone dispersion from Example 1 and purged with nitrogen for over 1 hour. The contents were then heated under a nitrogen blanket to between 140 and 150⁰C to form an almost colourless solution. While maintaining a nitrogen blanket, dried sodium carbonate (lO.βlg, 0.1 mole) and potassium carbonate (0.278g, 0.002 mole) was added. The temperature was raised to 200⁰C and held for 1 hour; raised to 250⁰C and held for 1 hour; raised to 315⁰C and maintained for 1 hour.

The reaction mixture was allowed to cool, milled and washed with acetone and water. The resulting polymer was dried in an air oven at 120⁰C producing a grey powder containing 0.5wt% of SWNTs in the composite. The polymer had a melt viscosity at 400⁰C, lOOOsec^"1 of 0.50 kNsm^"2.

Example 3 - Preparation of composite of polyetherketone and 5WNTS

The procedure of Example 1 was repeated except the diphenylsulphone/SWNT dispersion was not allowed to cool, but the reactor was fitted with a stirrer/stirrer guide, nitrogen inlet and outlet and charged with 4,4'- difluorobenzophenone (22.2βg, 0.102 mole), 4,4'- dihydroxybenzophenone (21.42g, 0.1 mole), and purged with nitrogen for over 1 hour. The contents were then heated under a nitrogen blanket to between 140 and 150⁰C to form an almost colourless solution. While maintaining a nitrogen blanket, dried sodium carbonate (10.81g, 0.102 mole) was added. The temperature was raised- gradually to 315⁰C over 2 hours then maintained for 1 hours .

The reaction mixture was allowed to cool, milled and washed with acetone and water. The resulting polymer was dried in an air oven at 120⁰C producing a grey powder containing 0.5wt% of SWNTs in the composite. The polymer had a melt viscosity at 400⁰C, lOOOsec^"1 of 0.54 kNsrrf².

Example 4 - Preparation of composite of polyethersulphone and SWNTs

A 250ml flanged flask fitted with a ground glass Quickfit lid, stirrer/stirrer guide, nitrogen inlet and outlet was charged with 4, 4' -dichlorodiphenylsulphone (29.54g, 0.102 mole), 4, 4 ' -dihydroxydiphenylsulphone (25.03g, 0.10 mole), and the solid diphenylsulphone/SWNT dispersion from Example 1 and purged with nitrogen for over 1 hour. The contents were then heated under a nitrogen blanket to between 140 and 150⁰C to form an almost colourless solution. While maintaining a nitrogen blanket, dried potassium carbonate (13.99g, 0.102 mole) was added. The temperature was raised to 180⁰C, held for 0.5 hours, raised to 205⁰C, held for 1 hour, raised to 225°C, held for 2 hours, raised to 265°C, held for 0.5 hours, raised to 28O⁰C and held for 2 hours.

The reaction mixture was allowed to cool, milled and washed with acetone/methanol (30/70) and water. The resulting polymer was dried in an air oven at 120⁰C producing a grey powder containing 0.5wt SWNTs.

Example 5 - Reprocessing of polyetheretherketone/SWNT composite with further polyetheretherketone

The procedures of Examples 1 and 2 were repeated on a scale to produce 20Og of the polyetheretherketone compound containing 5 wt% SWNTs. Separate lOOg samples of the polyetheretherketone/SWNT compound were blended with polyetheretherketone (PEEK™ 450P, Victrex pic) (90Og and 190Og respectively) using a ZSK 25 WLE Twin Screw Extruder, having a barrel temperature from 200⁰C to 39O⁰C, to produce composites containing 0.5 and 0.25wt% SWNTs respectively.

Example 6 - Reprocessing of polyetheretherketone/SWNT composite with polyetherimide and polyetheretherketone

The procedures of Example 1 and 2 were repeated on a scale to produce 20Og of the polyetheretherketone compound containing 5 wt% SWNTs. The polyetheretherketone/SWNT compound was blended with polyetheretherketone (PEEK™ 450P, Victrex pic) (120Og) and Polyetherimide (ϋltem 1000 from General Electric Company) (60Og) using a ZSK 25 WLE Twin Screw Extruder as for Example 5 to produce a compound containing 0.5wt% SWNTs.

Example 7 - Preparation of diphenulsulphone/MWNT dispersion

The procedure of Example 1 was repeated except the SWNTs (0.144g) were replaced with MWNTs (0.144g) producing a diphenylsulphone/MWNT dispersion .

Example 8 - Preparation of composite of polyetheretherketone and MWNT,s

The procedure of Example 2 was repeated except the solid diphenylsulphone/SWNT dispersion prepared in Example 1 was replaced by the solid diphenylsulphone/MWNT dispersion prepared in Example 7. The resulting polyetheretherketone/MWNT compound was dried in an air oven at 12O⁰C producing a grey powder containing 0.5wt% of MWNTs. The compound had a melt viscosity at 400⁰C, lOOOsec-¹ of 0.47 kNsm-².

By processes analogous to the processes in the aforementioned examples, composite materials may be prepared comprising other types of nanoparticles.

The invention is not restricted to the details of the foregoing embodiment ( s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings) , or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1. A process for preparing a composite material which comprises a polymeric material and nanoparticles, wherein the polymeric material is of a type which includes:

the process comprising the steps of:

2. A process according to claim 1, wherein said composite material comprises a said polymeric material which defines a matrix and additional material distributed within the matrix wherein a major amount of said additional material is comprised of said nanoparticles.

3. A method according to claim 1 or claim 2, wherein at least 0.05 wt% and less than 2wt% of nanoparticles are provided in said dispersion.

4. A material according to any preceding claim, wherein said fluid comprises a major amount of an organic material having a melting point of at least O⁰C and less than 500⁰C.

5. A process according to any preceding claim, wherein said fluid acts as a polymerisation solvent in step (ii) of the process.

6. A process according to any preceding claim, wherein said fluid represents at least 50wt% of the total wt% of solvent used in step (ii) .

7. A method according to any preceding claim, wherein, in step (ii), the nanoparticles are contacted with said fluid and dispersed by directing an oscillating energy source in to the fluid.

8. A material according to any preceding claim, wherein said polymeric material is a homopolymer having a repeat unit of formula

or a homopolymer having a repeat unit of general formula

or a homopolymer having a repeat unit of general formula

or a homopolymer having a repeat unit of general formula

or a random or block copolymer of at least two different units of IV and/or V; or at least two different units of IV* and/or V*; wherein A, B, C, D independently represent 0 or 1 and wherein m, r,s,t,v,w and z independently represent zero or a positive integer, E and E' independently represent an oxygen or a sulphur atom or a direct link, G represents an oxygen or sulphur atom, a direct link or a -O-Ph-0- moiety where Ph represents a phenyl group and Ar is selected from one of the following moieties (i)*, (i)**, (i) to (x) which is bonded via one or more of its .phenyl moieties to adjacent moieties

<^«n /^~° Λ /^~°Λ > (iv) (\ />

9. A material according to any preceding claim, wherein said polymeric material is selected from polyetheretherketone, polyetherketone, polyetherketoneketone , polyetherketoneetherketoneketone, polyetheretherketoneketone, polyethersulphone and polysulphone.

10. A process according to any preceding claim, wherein said polymeric material comprises polyetheretherketone,

11. A method according to any preceding claim, wherein said composite material includes 1 to 20wt% of nanoparticles .

12. A method according to any preceding claim, wherein said composite material comprises a major amount of a single polymeric material all of which is prepared in step

11

13. A process for preparing a second composite material which comprises a first polymeric material and x wt% of nanoparticles, wherein x wt% refers to the wt% of nanoparticles in the second composite material, the process comprising:

14. A process according to claim 13, wherein said first polymeric material comprises a polyaryletherketone, a polyarylethersulphone or polysulphone; and said further polymeric material comprises a polyaryletherketone, polyarylethersulphone, polyetherimide or PEI.

15. A composite material comprising polyetheretherketone and at least 0.1wt% of nanoparticles .

16. A composite material comprising a first polymeric material, a further polymeric material and nanoparticles.