ES2435801B1 - Procedure for obtaining a composite material consisting of carbon nanomaterial and polyether ether ketone - Google Patents

Abstract

Method for obtaining a composite material formed by carbon nanomaterial and polyether ether ketone. # The present invention relates to a process for obtaining a composite material formed by carbon nanomaterial (CNTs carbon nanotubes of the English carbon nanotubes or nanofibers Carbon CNFs from English carbon nanofibers or graphene) and polyether ether ketone (PEEK) based on the functionalization of the carbon nanomaterial with the monomers involved in the synthesis of PEEK. The carbon nanomaterial (CNTs, CNFs or graphene) is functionalized and incorporated at the beginning of the PEEK manufacturing process, taking part in the formation of the PEEK polymer structure, leaving the carbon nanomaterial bonded by covalent bonds to the polymer matrix, maximizing in this way the transfer of properties.

Description

DESCRIPTION

Procedure for obtaining a composite material consisting of carbon nanomaterial and polyether ether ketone.

The present invention relates to a process for obtaining a composite material consisting of 5 carbon nanomaterials (carbon nanotubes CNTs of English carbon nanotubes or carbon nanofibers CNFs of English carbon nanofibers or graphene) and polyether ether ketone (PEEK of English polyether ether ketone) based on the functionalization of the carbon material with the monomers that participate in the synthesis of PEEK.

Therefore, the invention could be framed in the area of composites and, in particular, in the field of functionalization of CNTs, CNFs or graphene.

BACKGROUND OF THE INVENTION

The incorporation of carbon nanomaterials (CNMs of the English carbon nanomaterials) in polymeric matrices, has been widely studied because it improves the mechanical, electrical and thermal properties of plastic materials and allows to extend the range of their applications. However, the integration of CNMs into polymeric matrices is generally complicated. A good dispersion of the reinforcement within the matrix is necessary, as well as a strong interfacial adhesion between the two phases of the compound so that the properties of the nanomaterials are effectively transferred to the polymer. CNMs have a great tendency to form agglomerates and, therefore, it is difficult to distribute them homogeneously in the polymer matrix.

The strategies generally used to solve these problems can be divided into i) Integration of the CNMs in a polymer solution, where ultrasound is used to improve the dispersion of the CNMs, ii) Solid phase mixing using grinding equipment to improve the dispersion and its subsequent shaping, iii) 25 Incorporation of the CNMs in the molten polymer by conventional extrusion techniques, conveniently modified and / or adapted to achieve an effective dispersion and iv) On-site polymerization in the presence of the CNMs, where they can be form covalent bonds between the matrix and the CNM and thereby maximize adhesion and transfer of properties to the polymer matrix.

 30

PEEK is a semi-crystalline and colorless thermoplastic polymer that offers a unique combination of high mechanical properties, temperature resistance and excellent chemical resistance. Due to its distinctive features, it is a suitable material for applications that require high mechanical performance under extreme conditions of temperature, chemical aggressiveness or high radiant energy. Consequently, it is used in all industries in general, and even more so in high-tech sectors, such as those in the aerospace, nuclear, chemical, electrical and food industries.

PEEK is obtained by polycondensation of bisphenolate with activated dihalides in the presence of a base. A typical reaction is that of 4,4-difluorobenzophenone with the hydroquinone disodium salt, which is generated in situ by deprotonation with sodium carbonate. The reaction is carried out around 300 ° C in 40 aprotic polar solvents, such as diphenylsulfone.

Scheme of the industrial synthesis of PEEK 45

The incorporation of CNMs in PEEK matrix reinforcement is currently an object of interest due to the enormous potential of these materials and because their incorporation is not immediate.

On the one hand, the lack of solubility of PEEK in conventional organic solvents makes it impossible to integrate 50 CNMs in solution. On the other hand, the processes of mixing in melting and mixing in solid state and later formed, even being the most studied, present technical difficulties due to having to be carried out at very high temperatures. Finally, the adhesion of the carbon nanomaterial to the matrix is not optimal.

The esterification of the reduced PEEK with oxidized CNMs gives good results, but its integration in the industrial production lines is complex since it requires, on the one hand, the reduction of the PEEK, on the other, the functionalization 55

of the CNMs with oxygenated groups and, finally, the reaction of the reduced PEEK with the functionalized CNMs ["Nanocomposite material reinforced with a polymer derivative grafted into a carbon material" A. M. Diez Pascual et al. WO2011 / 161294, "Novel nanocomposites reinforced with hydroxylated poly (ether ether ketone) -grafted carbon nanotubes" A. M. Diez Pascual et al. J. Mater. Chem. (2010) 20, 38, 8247-8256, “Grafting of Hydroxylated Poly (ether ether ketone) to the Surface of Single-Walled Carbon Nanotubes” A. M. Diez Pascual et al. 5 J. Mater. Chem. 20, 38, 8285-8296, 2010].

Another reported alternative deals with the functionalization of CNTs and CNFs with polyether ketone (PEK) with a structure similar to PEEK and which serves as a compatibilizer ["Carbon nanofibers and Nanotubes grafted with a hyperbranched poly (Ether-Ketone) and its derivates" L.S. Tan et al. Patent US 8, 173, 763, "Solubilization of Carbon 10 Nanofibers with a Covalently Attached Hyperbranched Poly (ether ketone)" Y.-D. H. Wang et al. Chemistry of Materials, 2008, 20 (4), 1502-1515.]. This method consists of a Friedel Kraft acylation in the presence of 2,4,6-trimethyl-phenoxy-benzoic acid using polyphosphoric acid (PPA) as Lewis acid.

This alternative has certain drawbacks. On the one hand, the high viscosity of the PPA makes the dispersion of CNTs and CNFs in the reaction medium very difficult, on the other, the elimination of the PPA once the functionalization is carried out requires huge amounts of water for its elimination, which It becomes total. Therefore, it is difficult to implement on an industrial scale and requires an additional final step of mixing with the PEEK.

Therefore, it is of interest to find a simple and easily implemented industrial process that incorporates CNTs, 20 CNFs or graphene in polymeric matrices of PEEK.

DETAILED DESCRIPTION OF THE INVENTION

The present invention describes a process for obtaining a composite material formed by carbon nanomaterial (CNTs or CNFs or graphene) and PEEK based on the functionalization of carbon material 25 with monomers 1 or 2 and its incorporation at the beginning of the PEEK synthesis process.

By "composite material" is meant, in the present invention, materials formed by two or more components distinguishable from each other, which possess properties that are obtained from combinations of their components, being superior to that of the materials that form them separately. 30

The term "carbon nanomaterial" (CNM of the English carbon nanomaterial) refers, in the present invention, to that carbon material whose size is nanometric. In the present invention this term encompasses carbon nanotubes, carbon nanofibers and graphene.

 35

In the present invention, the term "graphene" refers to an allotropic form of carbon consisting of a flat two-dimensional sheet formed by carbon atoms covalently bonded together in a hexagonal structure. The thickness of the graphene sheet is that of a single carbon atom and its variable surface according to the production method used.

 40

The term "carbon nanotubes" (CNT) refers, in the present invention, to an allotropic form of carbon, whose basic unit is a rolled graphite plane that forms a cylinder, forming tubes whose diameter is of the order of some nanometers. The structure can be considered as coming from a sheet of graphene rolled on itself. Depending on the degree of winding, and the way the original sheet is formed, the result can lead to nanotubes of different diameter and internal geometry. Four. Five

In the present invention, the term "carbon nanofibers" (CNF) refers to intermediate materials between micrometric fibers and CNTs.

The process of the present invention is not limited to a single type of CNT, it can be applied to any type of 50 CNTs, single layer, double layer or multiple layer CNTs.

"Single layer carbon nanotube" (single layer CNT or monolayer CNT), in the present invention, is understood as that CNT formed by a single tube. In English, single-layer carbon nanotubes are called single wall carbon nanotubes (SWCNTS), single-wall carbon nanotubes. 55

"Double layer carbon nanotube" (double layer CNT or double layer CNT), in the present invention, is understood as those CNT formed by two concentric nanotubes. In English, double-layer carbon nanotubes are called double wall carbon nanotubes (DWCNTs).

 60

The term "multi-layer carbon nanotube" (multi-layer or multi-layer CNT) refers to that CNT formed by several concentrically organized tubes. In English, multilayer carbon nanotubes are called multiple wall carbon nanotubes (MWCNT), multi-walled carbon nanotubes.

In the present invention, the carbon nanomaterial is incorporated into the PEEK matrix by an in situ polymerization carried out in the presence of CNTs or CNFs or graphene functionalized with the reaction monomers, which allows the incorporation of high nanomaterial loads of carbon maintaining a good dispersion within the matrix.

 5

During the process of the present invention, CNTs, CNFs and graphene are functionalized with each of the two monomers that are used in the PEEK polymerization reaction. These functional groups covalently bonded to the carbon material actively participate in the in situ polymerization reaction carried out with CNTs or CNFs or graphene functionalized with the respective monomers, which results in good dispersion and efficient transfer of material properties. carbon to the PEEK matrix. 10

The fact that monomers functionalized with CNTs or CNFs or graphene are used during the synthesis process of the NanoMaterial Carbon composite material (CNTs or CNFs or graphene) - PEEK, described in the present invention, greatly simplifies its industrial implementation because the lines of Existing production does not require substantial modifications. fifteen

In a first aspect, the invention relates to the process for obtaining a PEEK and carbon nanomaterial composite material comprising the polymerization of the monomer of formula (I)

 twenty

or the monomer of formula (II)

 25

with the compound of formula (III)

or the compound of formula (IV) respectively,

in the presence of a strong base and an aprotic polar solvent, where R1 and R4 are a monovalent cation respectively, and R2 and R3 are, independently, halogens.

By "halogen" is meant in the present invention bromine, chlorine, iodine or fluorine. 5

In a preferred embodiment, the monovalent cation is selected from the list comprising Na +, K + and Li +.

In another preferred embodiment, the carbon nanomaterial is selected from the list comprising CNF, SWCNTs, DWCNTs, MWCNTs and graphene. 10

In another preferred embodiment, the strong base is selected from the list comprising Na2CO3, K2CO3, KOH, NaOH and NH4OH.

In another preferred embodiment, the aprotic polar solvent is selected from the list comprising 1,2-15 dichlorobenzene, dimethylformamide (DMF), diphenylsulfone, dimethyl sulfoxide, acetonitrile, ethyl acetate, acetone and N-methyl pyrrolidone (NMP).

In another preferred embodiment, the duration of the polymerization has a value between 15 and 120 minutes.

 twenty

In another more preferred embodiment, the duration of the polymerization has a value between 45 and 90 minutes.

In another preferred embodiment, the polymerization temperature has a value between 100 ° C to 500 ° C.

In another more preferred embodiment, the polymerization temperature has a value between 250 ° C and 350 ° C. 25

In another preferred embodiment, the proportion of the carbon nanomaterial in the PEEK polymer matrix is between 0.05% (p) and 50% (p).

In another more preferred embodiment, the proportion of the carbon nanomaterial in the PEEK polymer matrix is between 0.1% (p) and 15% (p).

The second aspect of the invention relates to the process for obtaining the monomer of formula (I) by a sequence of reactions comprising the following steps:

 35

a) Functionalization reaction of the carbon nanomaterial with 4-aminophenol in the presence of a nitrite and a solvent to give the compound of formula (V).

b) Obtaining the functionalized monomer of formula (I) from the reaction of the compound of formula (V) with a strong base.

In a preferred embodiment, the nitrite of step a) is isoamyl nitrite.

 5

In another more preferred embodiment, the solvent of step a) is selected from the list comprising dimethylformamide (DMF) and N-methyl pyrrolidone (NMP).

In another preferred embodiment, the nitrite of step a) is sodium nitrite.

 10

In another more preferred embodiment, the solvent of step a) is hydrochloric acid.

In another preferred embodiment, step a) is performed at a temperature of 20 ° C to 90 ° C.

In another more preferred embodiment, step a) is performed at a temperature of 40 ° C to 70 ° C. fifteen

In another preferred embodiment, the reaction time of step a) has a duration between 1 and 24 hours.

In another more preferred embodiment, the reaction time of step a) has a duration between 10 and 15 hours.

In another preferred embodiment, the strong base of step b) is selected from the list comprising Na2CO3, K2CO3, KOH, NaOH and NH4OH.

 25

In another preferred embodiment, the reaction time of step b) has a duration between 1 and 72 hours.

In another more preferred embodiment, the reaction time of step b) has a duration between 36 and 60 hours. 30

The third aspect of the invention relates to the process for obtaining the monomer of formula (II) is obtained from the reaction of the monomer of formula (I) with the compound of formula (III) in the presence of a solvent.

In a preferred embodiment, the solvent is selected from the list comprising N-methyl pyrrolidone (NMP), diphenylsulfone, chloroform and dichloromethane.

In another preferred embodiment, the reaction time lasts between 1 and 24 hours.

In another more preferred embodiment, the reaction time lasts between 2 and 12 hours. 40

In another preferred embodiment, the reaction is carried out at a temperature of 50 ° C to 250 ° C.

In another more preferred embodiment, the reaction is carried out at a temperature of 90 ° C to 200 ° C.

 Four. Five

The compounds of the present invention may include isomers, depending on the presence of multiple bonds (eg, Z, E), including optical isomers or enantiomers, depending on the presence of chiral centers. The individual isomers, enantiomers or diastereoisomers and mixtures thereof fall within the scope of the present invention. The individual enantiomers or diastereoisomers, as well as mixtures thereof, can be separated by conventional techniques. fifty

Throughout the description and the claims the word "comprises" and its variants are not intended to exclude other technical characteristics, additives, components or steps. For those skilled in the art, other objects, advantages and features of the invention will be derived partly from the description and partly from the practice of the invention. The following examples and figures are provided by way of illustration, and are not intended to be limiting of the present invention.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1. Scheme of the functionalization of CNTs with the monomers that participate in the synthesis of PEEK 60

Figure 2. FTIR spectrum of the first stage of functionalization 1.

Figure 3. TGA of the product obtained in the first stage of functionalization1.

Figure 4. FTIR spectra of the starting CNTs, of the product obtained in stage 1 and of the product of stage 2 of functionalization 1.

Figure 5. Scheme for obtaining PEEK and CNM / PEEK composites by in situ polymerization with CNTs, CNFs or graphene functionalized with the PEEK precursor monomers. 5

Figure 6. Thermograms of the PEEK oligomers obtained by in situ polymerization.

EXAMPLE 10 A schematic of the functionalization of CNTs with the monomers that participate in the synthesis of PEEK is shown in Figure 1.

 fifteen

Reaction of the anchoring of the phenolic groups to the surface of the CNTs. First stage of functionalization 1.

In a type reaction, 250 mg of CNTs previously dispersed in the reaction solvent (DMF 100 mL) are mixed in an ultrasonic bath (30 min) with 25 mmol of 4-aminophenol and 2 mL of isoamyl nitrite. The reaction is heated at 60 ° C for 12 h to obtain the functionalized CNTs (phenol groups) as indicated in the scheme. The product obtained is filtered with a 0.1 micron pore size Ominopore membrane and washed with DMF and methanol. The product obtained is dried in the oven at 60 ° C. The product obtained weighs about 373 mg.

The material obtained at this stage was characterized by FTIR and thermogravimetry confirming the presence of the phenolic groups on the surface of the CNT. The FTIR spectrum confirmed the anchoring of the phenol group (1017 cm-1) as can be seen in Figure 2. The TGA data allowed to calculate the reaction performance (11% weight gain corresponding to the functional groups Figure 3).

Conversion of phenolic groups anchored to CNTs to phenolates. Second stage of functionalization 1. 30 Functionalization with monomer number 1

The phenol groups are transformed into phenolates in a sodium carbonate solution. In a 100 mg type reaction of functionalized CNTs are dispersed in 100 mL of a 0.05 M sodium carbonate solution sonicating for 30 min. The reaction is kept under stirring for 48h. After the time has elapsed, it is filtered and washed thoroughly with water. About 105 mg of dry product are obtained.

The material obtained was characterized by FTIR and TGA. The FTIR spectrum shows the disappearance of the band 40 to 1017 cm-1 associated with the vibration of OH indicating complete conversion to phenolate (Figure 4).

Anchoring reaction of dihalides to the surface of the CNTs. Functionalization with monomer number 2

For the functionalization of the CNTs with monomer number 2, the material functionalized with monomer 1 was obtained. Obtained as described above and reacted with 4,4-difluorobenzophenone (DFBP) used in the synthesis of PEEK. The reaction scheme is attached below. 5

200ml of a 2mg / ml dispersion of phenolate in NMP was reacted with 400 mg of DFBP at 160 ° C at three different reaction times: 2, 4 and 12 hours.

The reaction mixture is filtered under vacuum using a 0.1 µm OMNIPORE filter. The precipitate is washed with DMF (200 ml) and with MeOH (400 ml).

 fifteen

The product obtained is dried in an oven at 60 ° C for 24 hours.

The material obtained at this stage was characterized by FTIR and thermogravimetry confirming the presence of fluorinated groups on the surface of the CNT.

 twenty

Obtaining CNM / PEEK composite materials through in situ polymerization.

The scheme for obtaining CNM / PEEK composite materials through in situ polymerization with CNTs, CNFs or graphene functionalized with the PEEK precursor monomers is shown in Figure 5.

 25

The materials obtained showed a markedly improved thermal stability due to the effective transfer of properties of the CNMs to the matrix.

Also noteworthy is the possibility of obtaining composite materials that have a good dispersion with loads of 5, 10, 15 and 25%, and even higher, which are not possible by mixing methods in melt.

The composite materials obtained were studied by thermogravimetry and solid-state magnetic resonance imaging to determine the formation of bonds between the CNM and the matrix. Figure 6 shows the TGA thermograms of PEEK oligomers obtained according to the previous scheme. In said thermograms 35 the significant increase in thermal stability can be seen due to the presence of functionalized CNMs.

Claims (29)

1. Process for obtaining a material composed of polyether ether ketone and carbon nanomaterial comprising the polymerization of the monomer of formula (I)  5 or the monomer of formula (II)  10 with the compound of formula (III) or the compound of formula (IV) respectively,  fifteen in the presence of a strong base and an aprotic polar solvent, where R1 and R4 are a monovalent cation respectively, and R2 and R3 are independently halogens. 2. A method according to the preceding claim, wherein the monovalent cation is selected from the list comprising Na +, K + and Li +. 3. The method according to any of the preceding claims, wherein the carbon nanomaterial is selected from the list comprising carbon nanofibers, single layer carbon nanotubes, double layer carbon nanotubes, multiple layer carbon graphene nanotubes . 4. Method according to any of the preceding claims, wherein the strong base is selected from the list comprising Na2CO3, K2CO3, KOH, NaOH and NH4OH. 10 5. The method according to any of the preceding claims, wherein the aprotic polar solvent is selected from the list comprising 1,2-dichlorobenzene, dimethylformamide, diphenylsulfone, dimethyl sulfoxide, acetonitrile, ethyl acetate, acetone and N-methyl pyrrolidone.  fifteen 6. Method according to any of the preceding claims, wherein the duration of the polymerization has a value between 15 and 120 minutes. 7. Method according to the preceding claim, wherein the duration of the polymerization has a value of between 45 and 90 minutes. twenty 8. Method according to any of the preceding claims, wherein the polymerization temperature has a value between 100 ° C to 500 ° C 9. Method according to the preceding claim, wherein the polymerization temperature has a value of between 250 ° C and 350 ° C. 10. Method according to any of the preceding claims, wherein the proportion of carbon nanomaterial in the composite material is between 0.05% (p) and 50% (p).  30 11. Method according to the preceding claim, wherein the proportion of carbon nanomaterial in the composite material is comprised between 0.1% (p) and 15% (p). 12. Method according to any of the preceding claims, wherein the monomer of formula (I) is obtained by a sequence of reactions comprising the following steps: a) Functionalization reaction of the carbon nanomaterial with 4-aminophenol in the presence of a nitrite and a solvent to give the compound of formula (V).  40 b) Obtaining the functionalized monomer of formula (I) from the reaction of the compound of formula (V) with a strong base. 13. Method according to the preceding claim, wherein the nitrite of step a) is isoamyl nitrite  Four. Five 14. Method according to claim 12, wherein the nitrite of step a) is sodium nitrite. 15. A process according to claim 13, wherein the solvent of step a) is selected from the list comprising dimethylformamide (DMF) and N-methyl pyrrolidone (NMP).  fifty 16. Process according to claim 14, wherein the solvent of step a) is hydrochloric acid. 17. Method according to any of claims 12 to 16, wherein step a) is carried out at a temperature of 20 ° C to 90 ° C. 18. Method according to the preceding claim, wherein step a) is performed at a temperature of 40 ° C to 5 70 ° C. 19. Method according to any of claims 12 to 18, wherein the reaction time of step a) has a duration of between 1 and 24 hours.  10 20. Method according to the preceding claim, wherein the reaction time of step a) has a duration between 10 and 15 hours. 21. Method according to any of claims 12 to 20, wherein the strong base of step b) is selected from the list comprising Na2CO3, K2CO3, KOH, NaOH and NH4OH. fifteen 22. Method according to any of claims 12 to 21, wherein the reaction time of step b) has a duration of between 1 and 72 hours. 23. The method according to the preceding claim, wherein the reaction time of step b) has a duration between 36 and 60 hours. 24. Process according to any of claims 12 to 23, wherein the monomer of formula (II) is obtained from the reaction of the monomer of formula (I) with the compound of formula (III) in the presence of a solvent. 25 25. A process according to the preceding claim, wherein the solvent is selected from the list comprising N-methyl pyrrolidone, diphenylsulfone, chloroform and dichloromethane. 26. Method according to any of claims 24 to 25, wherein the reaction time has a duration between 1 and 24 hours. 27. Method according to the preceding claim, wherein the reaction time lasts between 2 and 12 hours.  35 28. A method according to any one of claims 24 to 27, wherein the reaction is carried out at a temperature of 50 ° C to 250 ° C. 29. A method according to the preceding claim, wherein the reaction is carried out at a temperature of 90 ° C to 200 ° C. 40