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 Inm.

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) 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 composite material comprising nanoparticles and a polymeric material which incorporates a modifying moiety which improves the compatibility of the polymeric material for the nanoparticles compared to the compatibility in the absence of said modifying moiety.

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 modifying moiety may comprise any type of moiety which can be incoporated into the polymeric material, for example by being convalently or ionically bonded thereto

and which may increase the compatibility between the polymeric material and selected nanoparticles. In one embodiment, said modifying moiety may comprise a polar moiety. This may be covalently bonded into the polymeric material to improve compatibility with charged and/or polar nanoparticles. In another embodiment, said modifying moiety may be non-polar and/or organic in character. It may improve compatibility with carbon- containing 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.

Said modifying moiety may be covalently bonded in the polymeric backbone of the polymeric material, as part of an end capping moiety of the polymeric material and/or as part of a moiety pendant from the polymeric backbone of the polymeric material. In some embodiments, two different types of modifying moiety may be incorporated. For example, said polymeric material may include a modifying moiety which is part of an end capping moiety and a modifying moiety which is covalently bonded in the polymeric backbone or is pendant therefrom. Preferably, the polymeric material includes only ^" a single type of modifying moiety.

When said modifying moiety is covalently bonded in the polymeric backbone, it preferably includes two single covalent bonds to adjacent moieties in the backbone.

When said modifying moiety is part of an end-capping moiety, it preferably includes one single covalent bond to an adjacent moiety in the polymeric backbone.

Said modifying moiety may include fused aromatic rings. Such a modifying moiety preferably includes fused rings having (4n+2) π electrons, where n is an integer of 2 or greater. Integer n is preferably 2 or 3. Said fused rings preferably comprise at least two fused six-membered rings. Although the fused rings of said modifying moiety may include one or more heteroatoms, it preferably does not include any heteroatom. Preferably, the fused rings of said modifying moiety are made up of carbon atoms only.

Said modifying moiety may comprise an optionally- substituted naphthalenyl, anthracenyl or pyrenyl moiety, with optionally-substituted naphthalenyl and pyrenyl moieties being preferred.

Although such a modifying moiety could be substituted, for example with another aromatic and/or fused ring moiety, it is preferably unsubstituted. In this case, said modifying moiety suitably consists essentially of a said moiety which includes at least two fused aromatic rings as described.

When .the modifying moiety bonded in the polymeric backbone comprises a naphthalenyl moiety, said moiety is preferably bonded via its 1,5 - carbon atoms; when it comprises an anthracenyl moiety said moiety is preferably bonded via its 2,3- or 5,10- carbon atoms; and when it comprises a pyrenyl moiety, said moiety is preferably bonded via carbon atom on separate rings.

When the modifying moiety acting as an end-capping moiety comprises a naphthalenyl moiety, said moiety is preferably bonded to the backbone via its 1- or -5- carbon atoms; when it comprises an anthracenyl moiety, said moiety is preferably bonded via its 2, 3, 5 or 10 carbon atoms; and when it comprises a pyrenyl moiety, said moiety is preferably bonded via its 1- carbon atom.

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.

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 composite material may include up to 5wt% of said nanoparticles, for example 1 to 5 wt%, preferably 2 to 5wt% of nanoparticles.

Said polymeric material may include at least 90 mole %, suitably includes greater than 94 mole %, preferably includes greater than 96 mole %, especially includes 98

mole % or greater of repeat units which do not incorporate a said modifying moiety. Suitably up to 10 mole %, preferably up to 6 mole %, more preferably up to 4 mole %, especially up to 2 mole % of units, for example repeat units or end capping units, of said polymeric material incorporate said modifying moiety.

Thus, preferably, said composite material comprises nanoparticles in combination with a first type of polymeric material which does not incorporate a said modifying moiety and a second type of polymeric material which does incorporate a said modifying moiety, wherein suitably the first and second polymeric materials are essentially the same (i.e. any molecular weight differences are ignored) except that said second polymeric material comprises a form of said first polymeric material which has been modified by incorporation into the first polymeric material of a modifying moiety in the polymeric backbone or as an end group.

When said modifying moiety is covalently bonded in the polymeric backbone or is pendent from the polymeric backbone, said modifying moiety suitably represents a modified repeat unit [A] of the polymeric material which is distributed amongst repeat units [B] . The ratio of the mole % of repeat units [B] to repeat units [A] in said polymeric material may be at least 5, preferably at least 20, more preferably at least 35, especially at least 50. The ratio may be less than 200, preferably less than 100, more preferably less than 75, especially less than 50. Repeat units [B] preferably do not include modifying moieties, for example fused aromatic rings. In preferred embodiments they consist essentially of:

(a) phenyl moieties

(b) ketone and/or sulphone moieties; and

(c) ether and/or thioether moieties.

Repeat unit [A] may differ from repeat unit [B] by the inclusion of a modifying moiety, for example said fused aromatic rings between a pair of ether and/or thioether moieties in repeat unit [A] .

It will be appreciated that when said modifying moiety is covalently bonded in or pendent from the polymeric backbone, the majority or all polymer chains in the polymeric material may include one or more repeat units [A] . However, the level of repeat units [A] is suitably selected so that the bulk properties of the polymeric material incorporating units [A] is not significantly different from the properties of the polymeric material in the absence of units [A] .

When said modifying moiety is part of an end-capping moiety, said composite material may include said polymeric material which includes said modifying moiety and a polymeric material (hereinafter "said unmodified polymeric material") which is not end-capped by said modifying moiety. The ratio of the mole % of unmodified polymeric material to said modified polymeric material in said composite material may be at least 5, preferably at least 20, more preferably at least 35, especially at least 40. The ratio may be less than 200, preferably less than 100, more preferably less than 75, especially less than 50. In preferred embodiments, both said modified polymeric

material and said unmodified material comprise a major amount of repeat units which include:

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

Preferably, the repeat units of said modified and unmodified materials are identical; the materials preferably only differ in the nature of the end-capping of the polymer chains .

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 C ₂ 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-O- 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

w // ° ^~ \ // (iv) ( _χ /)

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_i ₀ , especially C ₁ - 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, CyF _2y +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=CF ₂ , CN, NO ₂ 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 _f Ar,m _r 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

Of-cojfo-H-G- ^■ O-H-co-fo- -f ^E >ff(δ}]-m _E /A IV

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 z 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- rαoiety; (xvi) is selected from a l _f 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) , (ii) , (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 sulphone moieties and in conjunction with ether moieties. That is, in the preferred class, the polymeric material does not include repeat units which include -S- or aromatic groups other than phenyl. Preferred polymeric materials include:

(a) a polymer consisting essentially of units of formula IV wherein Ar represents moiety (iv), E and E ¹ 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 ¹ 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 (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 14O ⁰ C, suitably at least 144 ⁰ C, preferably at least 154°C, more preferably at least 160 ⁰ C, especially at least 164 ⁰ C. In some cases, the Tg may be at least 17O ⁰ C, or at least 190 ⁰ C or greater than 25O ⁰ C or even 300 ⁰ C.

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 25 ⁰ C on a solution of the polymer in concentrated sulphuric acid of density 1.84gcrα ^~3 , said solution containing Ig of polymer per 100cm ^'3 of solution. IV is measured at 25 ⁰ C on a solution of polymer in concentrated sulphuric acid of density 1.84gcm ³ , said solution containing O.lg of polymer per 100cm ³ 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 300 ⁰ C.

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

The invention extends to a composite material comprising nanoparticles, a first polymeric and a second polymeric material, wherein said first and second polymeric materials are essentially the same except that said second polymeric material comprises a modifying moiety in its polymeric backbone or as an- end group which modifying moiety is not included in said first polymeric material.

According to a second aspect of the invention, there is provided a method of making a composite material which comprises contacting nanoparticles, for example fullerene

moieties with a polymeric material which incorporates a modifying moiety which includes fused aromatic rings.

Said nanoparticles and/or fullerene moieties and said polymeric material may have any feature described according to said first aspect.

In the method, initial contact of said nanoparticles and polymeric material preferably take place during a polymerisation process in which said polymeric material is prepared prior to isolation of said polymeric material. In a first embodiment, the method includes contacting said nanoparticles with a precursor compound which is subsequently incorporated into said polymeric material. Said precursor compound may be a monomer or an end-capping precursor. In a second embodiment, said polymeric material may be prepared but not isolated and said nanoparticles may be contacted with the polymeric material and, thereafter, the composite material is isolated.

In said first embodiment, said nanoparticles may be contacted with a mixture comprising all the precursors of moieties necessary to prepare said polymeric material. The mixture may also include a solvent or solvents used in the polymerisation reaction to produce the polymeric material. Preferably, the method includes: (i) dispersing said nanoparticles in a fluid to prepare a nanoparticles dispersion of nanoparticles in said fluid; and (ii) subsequently contacting the dispersion prepared with one or more precursors (e.g. one or more monomers) which are polymerisable to prepare said polymeric material. The mixture prepared in step (ii) may then be polymerised to prepare said polymeric material.

Preferably, said dispersion used in step (i) includes a monomer or end-capping precursor which incorporates a precursor of said modifying moiety for example fused aromatic rings and is arranged to define the modifying moiety in the polymeric material. Preferably, the only type of material in the dispersion used in step (i) which is subsequently incorporated into the polymeric material is a precursor of said modifying moiety for example a material which incorporates fused aromatic rings.

In the first embodiment, at least 0.05 wt% of nanoparticles, for example fullerene moieties, suitably at least 0.10wt%, preferably at least 0.15wt%, more preferably at least 0.20wt%, especially at least 0.25wt% of such nanoparticles may be dispersed in said dispersion prepared in step (i) . The dispersion may include less than 15wt%, suitably less than 10wt%, preferably less than 5wt%, more preferably less than lwt%, especially 0.5wt% or less of said 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.

Suitably, . at least 0.15wt%, preferably at least 0.3wt%, more preferably at least 0.5wt%, especially at least 0.8wt% of said monomer or end-capping precursor is incorporated in the dispersion prepared in step (i) . The dispersion may include less than 6wt%, suitably less than 3wt%, preferably less than 1.8wt%, more preferably less than 1.2wt%, of said monomer or end-capping precursor.

Preferably at least 0.5wt% and less than 2wt% of said monomer or end-capping precursor is provided in said dispersion.

Said fluid used in step (i) preferably comprises a major amount of an organic material which may have a melting point of at least 0 ⁰ C, suitably of at least 15 ⁰ C, preferably at least 4O ⁰ C, more preferably of at least 8O ⁰ C, especially at least 100 ⁰ C. The melting point is suitably less than 300 ⁰ C, preferably less than 25O ⁰ C, more preferably less than 200 ⁰ C, especially less than 150 ⁰ C. Said organic material may have a boiling point of less than 500 ⁰ C, preferably less than 400 ⁰ C. The boiling point may be greater than HO ⁰ C, preferably greater than 200 ⁰ C.

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 (or end-capping precursor) 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 fullerene moieties 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 (ii) . Preferably, said fluid is a polar organic solvent.

Preferably, in step (i) , the nanoparticles, for example fullerene moieties are contacted with said fluid and said monomer or end-capping precursor which incorporates modifying moieties, for example fused aromatic rings 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 50 ⁰ C 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 solidify said fluid with said dispersed nanoparticles 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.

In said second embodiment, the polymeric material prepared, at an elevated temperature, and suitably still in the presence of fluids, for example solvents used in the polymerisation, is preferably contacted with said nanoparticles, for example fullerene moieties. The nanoparticles are preferably dispersed in the fluid in the

manner described above according to said first embodiment and, suitably, said fluid in which they are dispersed is the same as used in the polymerisation.

Said polymeric material which incorporates a modifying moiety may be prepared via an electrophilic or nucleophilic process. Electrophilic processes such as those described in EP 1170318 (Gharda) and nucleophilic processes such as described in EP 1879 (ICI) may be modified so that a said precursor compound which incorporates a precursor of said modifying moiety is included with one or more other monomers used in the polymerisation .

Polymers having units I, II, III, IV, IV*, V and/or V described above may be prepared by:

(a) polycondensing a compound of general formula

with itself wherein Y ¹ represents a halogen atom or a group -EH and Y ² represents a halogen atom or, if Y ¹ represents a halogen atom, Y ² represents a group E ¹ H; or

(b) polycondensing a compound of general formula

with a compound of formula

and/or with a compound of formula

wherein Y ¹ represents a halogen atom or a group -EH (or - E ¹ H if appropriate) and X ¹ represents the other one of a halogen atom or group -EH (or -E ¹ H if appropriate) and Y ² represents a halogen atom or a group -E ¹ H and X ² represents the other one of a halogen atom or a group -E ¹ H (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.

When said modifying moiety represents a modified repeat unit [A] of the polymeric material, a monomeric precursor of said repeat unit [A] may be polycondensed with said compounds of formulae VI, VII and/or VIII referred to. Said monomeric precursor may be of formula Y ³ - [A] -Y ⁴ ' wherein Y ³ and Y ⁴ independently represent hydrogen or halogen atoms .

Preferably, where Y ¹ , Y ² , X ¹ , X ² , Y ³ and/or Y ⁴ 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 ¹ and Y ² represents a fluorine atom and the other represents an hydroxy group. More preferably in this case, Y ¹ represents a fluorine atom and Y ² 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. The monomeric precursor of said repeat unit [A] used may have one of Y ³ and Y ⁴ representing a fluorine atom and the other representing a hydrogen atom. It should be appreciated

that the hydrogen atom will be bonded to an oxygen atom in the adjacent repeat unit [A] .

When a process described in paragraph (b) is carried out, preferably, Y ¹ and Y ² each represent an hydroxy group.

Preferably, X ¹ and X ² each represent a halogen atom, suitably the same halogen atom. Y ³ and Y ⁴ of the monomeric precursor used may represent the same atoms and preferably both represent hydrogen atoms so that the monomeric precursor preferably includes hydroxyl groups.

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 U Delius, Macromolecules 21_ _r 517 (1989) and P A Staniland, Bull, Soc, Chem, BeIg., _98_ (9-10), 667 (1989).

When said modifying moiety is part of an end-capping moiety, said end-capping moiety may be represented by moiety [C] and said end-capping precursor may be of formula Y -[C] wherein Y ⁵ represents a hydrogen or halogen atom, paid precursor may be polycondensed with said compounds of formulae VI, VII and/or VIII referred to. Preferably, Y ⁵ represents a hydrogen atom so that the said end-capping precursor includes a single hydroxyl group (and preferably no other functional group which can participate in the polycondensation) .

The mole % of said monomeric precursor Y ³ - [A] -Y ⁴ or said end-capping precursor Y ⁵ - [C] relative to the total moles of monomers (or other moieties) incorporated into the polymeric material in the polycondensation reactions described, is preferably less than 5 mole %, more preferably less than 4 mole %, especially 2.5 mole % or less. The mole % is preferably greater than 0.25 mole %, especially greater than 0.5 mole %.

Polycondensation as aforesaid may be carried out in a solvent which 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 R ⁵¹ is a direct link, an oxygen atom or two hydrogen atoms (are attached to each benzene ring) and R ⁵⁰ and R ⁵² 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-T 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. 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.

Said solvent is preferably diphenyl sulphone.

Said composite material of the first aspect may include said polymeric material which incorporates a said modifying moiety (hereafter "said modified polymeric material") and another polymeric material which may be formed in a polymerisation reaction in which said modified polymeric material is formed. Additionally, said composite material may include a further polymeric material. A composite material (hereinafter "second composite material") may be prepared from said composite material (hereafter "first composite material") as described according to said third aspect below.

The invention extends to a method of preparing a polymeric material which incorporates a modifying moiety, the method comprising polycondensing compounds of formulae VI, VII and/or VIII with either: a monomeric precursor of a said repeat unit [A] ; or a said end-capping precursor of formula Y ⁵ - [C] .

According to a third aspect of the invention, there is provided a method of making a second composite material which -comprises : ^{* ~}

i) selecting a first composite material according to said first aspect which includes nanoparticles and a said polymeric material (hereinafter "said modified polymeric material"); and

ii) contacting said first composite material with further polymeric material in order to prepare said second composite material.

The method of the third aspect may be used to reduce the wt% of nanoparticles in said first composite material and/or to incorporate into said first composite material different types of polymers.

Said modified polymeric material in said first composite material may be any of the polymeric materials described herein, for example, according to the first aspect. Said modified polymeric material is preferably melt processible. Its degradation temperature is suitably higher than its melting point (suitably by at least 10 ⁰ C, preferably by at least 20 ⁰ C) so that it can be extruded without significant degradation. Said modified polymeric material preferably includes aryletherketone (especially from etheretherketone, etherketone and etherketoneketone) , arylethersulphone (especially ethersulphone) and polysulphone repeat units. In the most preferred embodiment said modified polymeric material includes etheretherketone repeat units.

Said further polymeric material is preferably melt processible. Its degradation temperature is suitably higher than its -melting -point (suitably by ^" at least 1O ⁰ C, preferably by at least 20 ⁰ C) 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 modified polymeric material and said

further polymeric material may be substantially the same. For example, both may substantially be polyetheretherketone (albeit said modified polymeric material will incorporate modifying moieties) . In this case, the process of the third aspect may be used to adjust the level of nanoparticles moieties in the first composite material to a desired level. In another embodiment, said modified and said further polymeric materials may be different. For example, said modified polymeric material could substantially be a polyaryletherketone (albeit modified by incorporation of modifying moieties) , 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 400 ⁰ C, preferably in the range 340 to 400 ⁰ C, more preferably in the range 340 to 38O ⁰ C.

In the process of making said second composite, 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 5O ⁰ C, preferably greater than 100 ⁰ C, more preferably greater than 200 ⁰ C, especially at greater than 300 ⁰ C. The temperature

preferably does not exceed 500 ⁰ C, more preferably does not exceed 450 ⁰ C 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 described 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.

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

According to a fourth aspect of the present invention, there is provided any novel polymeric material described

herein. Said polymeric material preferably incorporates a modifying moiety as described.

Said polymeric material may be as described according to said first aspect. In a preferred embodiment, said polymeric material comprises:

(A) a repeat unit [A] which incorporates a modifying moiety (e.g. fused aromatic rings) and a repeat unit [B] which does not include said modifying moiety (e.g. any fused aromatic rings) , wherein the ratio of the mole % of repeat units [B] to repeat units [A] in said polymeric material is at least 5 and is preferably in the range 35 to 75; or

(B) a repeat unit [B] which includes an end-capping moiety which incorporates a modifying moiety.

Repeat unit [B] preferably only includes:

(a) phenyl moieties;

(b) ketone and/or sulphone moieties; and

(c) ether and/or thioether moieties.

Repeat unit [B] is preferably selected from: aryletherketone (especially etheretherketone, etherketone

_ and etherketeneketone) units o ^' r ^{"" "} arylethersulphone

(especially ethersulphone) units. The most preferred units are etheretherketone units.

Said modifying moiety of the fourth aspect may be as described in any statement herein. It is preferably

selected from optionally-substituted naphthalenyl, anthracenyl and pyrenyl moieties.

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 may be used in electrostatic discharge (ESD) or in 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 - thre 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 of Houston USA.

MWNTs - refers to "multi-walled carbon nanotubes" obtained from the same source as the SWNTs.

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 end group modified polyetheretherketone

A 250ml flanged flask fitted with a ground glass 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), 1-hydroxypyrene

(0.44g, 0.002 mole) and diphenylsulphone (49g) and purged with nitrogen for over 1 hour. The contents were then heated under a nitrogen blanket to between 140 and 150 ⁰ C to form an almost colourless solution. While maintaining a nitrogen blanket, dried sodium carbonate (10.6Ig, 0.1 mole) and potassium carbonate (0.278g, 0.002 mole) was added. The temperature was raised to 200 ⁰ C and held for 1 hour; raised to 250 ⁰ C and held for 1 hour; raised to 300 ⁰ C and SWNTs (0.144g) were added. The temperature was then raised to 315°C 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 120 ⁰ C producing a grey powder containing 0.5wt% of SWNTs in the composite. The polymer had a melt viscosity at 400 ⁰ C, lOOOsec ^"1 of 0.50 kNsπf ² .

Example 2 - Preparation of end group modified polyetheretherketone

The procedure in Example 1 was repeated except the quantity of 1-hydroxypyrene was increased (0.88g, 0.004 mole) . The final product had a melt viscosity at 400 ⁰ C, lOOOsec ^"1 of 0.40 kNsitf ² .

Example 3 - Preparation of composite of polyetherketone and SWNTs by pre-dispersion

Step (i)

A jacketed glass reactor was charged with diphenyl sulphone (49g), 1-hydropyrene (0.44g, 0.002mol) and SWNTs

(0.144g). The contents were heated to 140 ⁰ C (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 may then be allowed to cool further under ambient conditions.

Step (ii)

A 250ml flanged flask fitted with a ground glass Quickfit lid, stirrer/stirrer guide, nitrogen inlet and outlet was charged with 4, 4' -dif-luorobenzophenone (22.26g, ^*" 0.102 mole), 4, 4' -dihydroxybenzophenone (21.42g, 0.1 mole), and the diphenylsulphone/1-hydroxypyrene/SWNT dispersion prepared in step (i) and purged with nitrogen for over 1 hour. The contents were then heated under a nitrogen blanket to between 140 and 150 ⁰ C 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 315 ⁰ C 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 120 ⁰ C producing a grey powder containing 0.5wt% of SWNTs in the composite. The polymer had a melt viscosity at 400 ⁰ C, lOOOsec ^"1 of 0.51 kNsrtf ² .

Example 4 - Preparation of composite of end group modified polyethersulphone and SWNTs by pre-dispersion

The procedure in Example 3 step (i) was repeated except the 1-hydroxypyrene (0.44g, 0.002 mole) was replaced with 1-naphthol (0.29g, 0.002 mole) to produce a diphenylsulphone/1-naphthol SWNT dispersion.

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 diphenylsulphone/1-naphthol dispersion and purged with nitrogen for over 1 hour. The contents were then heated under a nitrogen blanket to between 140 and

145 ⁰ C 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 180 ⁰ C, held for 0.5 hours, raised to 205 ⁰ C, held for 1 hour, raised to 225°C, held for 2 hours, raised to

265 ⁰ C, held for 0.5 hours, raised to 280 ⁰ C 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 120 ⁰ C producing a grey powder containing 0.5wt SWNTs.

Example 5 - Preparation of composite of polyetheretherketone with main chain modification and SWNTs by post-dispersion

A 250ml flanged flask fitted with a ground glass Quickfit lid, stirrer/stirrer guide, nitrogen inlet and outlet was charged with 4, 4' -difluorobenzophenone (22.26g, 0.102 mole), hydroquinone (ll.Olg, 0.1 mole), 1,5- dihydroxynaphthalene (0.32g, 0.002 mole) and diphenylsulphone (49g) and purged with nitrogen for over 1 hour. The contents were then heated under a nitrogen blanket to between 140 and 150 ⁰ C 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 200 ⁰ C and held for 1 hour; raised to 250 ⁰ C and held for 1 hour; raised to 300 ⁰ C and SWNTs (0.144g) were added. The temperature was then raised to 315°C 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 120 ⁰ C producing a grey powder containing 0.5wt% of SWNTs in the composite. The polymer had a melt viscosity at 400 ⁰ C, lOOOsec ^"1 of 0.48 kNsrrf ² .

Example 6 - Preparation of composite of polyetheretherketone with main chain modification and SWNTs by pre-dispersion

Step (i)

A jacketed glass reactor was charged with diphenyl sulphone (49g) , 1,5 dihydroxynaphthalene (0.32g, 0.002mol) and SWNTs (0.144g). The contents were heated to 140 ⁰ C (eg using hot oil circulation) and were 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 may then be allowed to cool further under ambient conditions.

Step (ii)

A 250ml flanged flask fitted with a ground glass Quickfit lid, stirrer/stirrer guide, nitrogen inlet and outlet was charged with 4, 4' -difluorobenzophenone (22.2βg, 0.102 mole), 4, 4' -dihydroxybenzophenone (21.42g, 0.1 mole), and the diphenylsulphone/dihydroxynaphthalene/SWNT dispersion prepared in step (i) and purged with nitrogen for over 1 hour. The contents were then heated under a nitrogen blanket to between 140 and 150 ⁰ C to form an almost colourless solution. While maintaining a nitrogen blanket, dried sodium carbonate ^' (10.8Tg, 0.102 mole) was added. The temperature was raised gradually to 315 ⁰ C over 2 hours then 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 120 ⁰ C producing a grey powder

containing 0.5wt% of SWNTs in the composite. The polymer had a melt viscosity at 400 ⁰ C, lOOOsec ^"1 of 0.51 kNsrrf ² .

Example 7 - Compounding polyetheretherketone/SWNT composite with further polyetheretherketone

The procedures of Example 3 was repeated except the 4,4'- dihydroxybenzophenone was replaced with hydroquinone on a scale to produce 200g of the PEEK compound containing 5 wt% SWNTs. The PEEK/SWNT compound (10Og) was blended separately with polyetheretherketone (PEEK™ 450P, Victrex pic) (90Og) and (190Og) using a ZSK 25 WLE Twin Screw Extruder to produce compounds containing 0.5 and 0.25wt% SWNTs.

Example 8 - Compounding polyetherketone/SWNT composite with further polyetherketone and polyetherimide

The procedure of Example 3 was repeated on a scale to produce 20Og of the PEK compound containing 5 wt% SWNTs.

The PEK/SWNT compound was blended with polyetherketone

(PEEK HT™ 22P, Victrex pic) (120Og) and Polyetherimide

(Ultem 1000 from General Electric Company) (60Og) using a

ZSK 25 WLE Twin Screw Extruder to produce a compound containing 0.25wt% SWNTs.

Example 9 , - Preparation - of - en ^' d gro ^' up modified polyetheretherketone and MWNTs

The procedure of Example 1 was repeated except the SWNTs (0.144g) were replaced with MWNTs (0.144g) producing a PEEK/MWNT compound containing 0.5wt% MWNTs.

Example 10 - Preparation of composite of_ polyotheretherketone and MWNTs

The procedure of Example 3 was repeated except the diphenylsulphone/SWNT dispersion prepared in step (i) was replaced by a diphenylsulphone/MWNT dispersion.

The resulting PEEK/MWNT compound was dried in an air oven at 120 ⁰ C producing a grey powder containing 0.5wt% of MWNTs. The compound had a melt viscosity at 400 ⁰ C, lOOOsec ^"1 of 0.47 kNsrrf ² .

By processes analogous to the processes in the aforementioned examples, composite materials may be prepared comprising other types of nanoparticles in combination with polymeric materials modified for compatibility therewith.

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.