HK1171039B - Synthesis method using ionic liquids - Google Patents

Abstract

The disclosures herein provide a process for conducting a nucleophilic aromatic substitution reaction in an ionic liquid and forming a polymeric material.

Description

Synthesis method using ionic liquid

Technical Field

The disclosure herein relates to the preparation of polymers using nucleophilic aromatic substitution reactions in ionic liquids. The present disclosure relates to the preparation of polymers belonging to the class of polyetherketones and polyethersulfones. More particularly the disclosure relates to the use of ionic liquids as a medium for the synthesis of polyetherketones, also known as Polyetheretherketones (PEEK), by solution or suspension polymerization.

Background

Polyetheretherketone (PEEK) is known at least from the Ashford's dictionary of Industrial Chemicals, 1994, wavelet Productions Ltd, p.733. The Victrex PLC is of the following repeating structureThe manufacturer of polyetheretherketone polymers.

Known industrial techniques for preparing PEEK from 4, 4' -difluorobenzophenone employ, for example, high temperature synthesis up to 300 ℃ in diphenylsulfone solvents.

However, the use of diphenyl sulfone as a solvent in this reaction is problematic because of the limitation of the solvent on the liquid range at lower temperatures. The use of diphenyl sulfone at room temperature leads to the formation of "toffee" or a high viscosity mixture of product and solvent when product separation occurs, since the solvent is a solid under those conditions. Diphenyl sulfone is also toxic and its use has environmental problems.

An alternative solvent for the industrial production of PEEK is N-methylpyrrolidone (NMP). EP1464662 to Mitsui includes a disclosure in which NMP is the solvent used. However, there are also problems associated with this solvent because it has a considerable vapor pressure at the temperatures required for the reaction. This means that high pressures are required and thus special high pressure process equipment is required. The use of relatively volatile solvents also means that the heat that can be introduced into the reaction is limited because reflux of the solvent needs to be avoided.

As indicated above, the known industrial synthesis of PEEK uses potassium carbonate as a base. This is because the corresponding sodium carbonate is not sufficiently soluble in the organic reaction solvent used. Potassium carbonate is more expensive than the corresponding sodium salt and therefore it would be beneficial to be able to use sodium carbonate as the base. It is known in the art that the type and particle size of the base used in the formation of PEEK is very important because of the low solubility of the base in conventional solvent media. WO2010046483 for example discusses the special need to avoid large particle-bearing sodium carbonate in the synthesis because of potential product contamination. This limitation can be avoided with the use of ionic liquid solvents.

Another feature of known industrial condensation polymerization is the problem related to the purity of the polymer produced. In the case of the above PEEK synthesis, the by-product potassium fluoride is largely insoluble in the solvent system used and is therefore entrapped in the PEEK polymer matrix as it is formed. The entrapped potassium fluoride is then very difficult to remove and this places a limit on the polymer purity that can be obtained via known industrial syntheses.

The reaction of hydroquinone with 4, 4' -difluorobenzophenone (nucleophilic aromatic substitution reaction) discussed above provides PEEK as a partially crystalline thermoplastic polymer. The polymers are characterized by their outstanding chemical and thermal resistance. The electrical insulation of the polymer is known to be similar to that of fluoropolymers. The use of PEEK includes cable insulation and plastic mechanical parts. Known processing methods applied to PEEK are extrusion and injection molding on conventional equipment.

One polyether sulfone polymer known in the art is synthesized as a reaction of a dihydric phenol with bis (4-chlorophenyl) sulfone, with elimination of sodium chloride to form a polyether:

nHOC₆H₄OH+n(ClC₆H₄)₂SO₂+nNa₂CO₃→[OC₆H₄SO₂C₆H₄]_n+2nNaCl+nH₂O+nCO₂

the dihydric phenol is typically bisphenol a or, as indicated above, hydroquinone. Polyethersulfones are engineering plastics possessing excellent thermal stability and mechanical strength. The structure and properties of a particular polyethersulfone known as PES are discussed in engineering thermoplastics (ISBN 0-8247-7294-6) Margolis J.M.Ed.Rigby R.B., chapter 9, 235.

Ionic liquids or low temperature molten salts are known in the art as very low volatility solvents suitable for carrying out a series of chemical reactions. Polymerization in Ionic Liquids has been described previously, but these are mainly polymerizations giving amorphous polymers such as polymethyl methacrylate (PMMA) or polyolefins (Polymer Synthesis in Ionic Liquids, Haddlelton D.M., Welton T., Carmichael A.J., in Ionic Liquids Synthesis book; Wasser chemical P., Welton T., second edition, 2008, Wiley). These polymers typically have good solubility in a wide range of organic solvents, and thus the choice of the reaction solvent is not critical. Furthermore, these polymerization reactions are distinguished from the industrial syntheses discussed above, for example, in that they proceed via a free radical mechanism and not via a polycondensation mechanism, such as in the synthesis of PEEK. Limitations on the solvents used in the polycondensation reaction are known in the art. For example, PEEK is one of the highest melting semi-crystalline polymers that can be prepared and, as such, the oligomers produced during its formation have low solubility and crystallize from the reaction medium. In the case of polycondensation, it is known in the art that the molecular weight of the polymer formed is highly dependent on the solubility of the polymer in the solvent. EP1464662 states that the polymerisation is only carried out when the polymer formed is soluble in the solvent, and for PEEK which is known to show very low solubility in conventional solvents, since this polymer will deposit at low conversion. Polymer (Polymer)1988, 29, 1902 also states that the solubility of the polymers formed is a fundamental limitation to the use of traditional solvents in the formation of PEEK. Therefore, the choice of solvent for polycondensation is very critical and to date, ionic liquids have not been considered as useful solvents for the preparation of high molecular weight polymers such as PEEK.

Ionic liquids have been used in the art as solvents for nucleophilic aromatic substitution reactions for ether synthesis (see Welton t., newton i., Perez-Arlandis j.m., Organic Letters 2007, 9, 5247). However, it has not previously been thought that they can be used as solvents for polymer synthesis via nucleophilic aromatic substitution routes.

Summary of The Invention

The disclosure herein provides methods of conducting nucleophilic aromatic substitution reactions in ionic liquids and forming polymeric materials. Accordingly, in one aspect the present invention relates to the use of an ionic liquid as a solvent in a nucleophilic aromatic substitution reaction to form a polymeric material.

The present invention is based on the unexpected discovery that ionic liquids can be used as solvents for nucleophilic aromatic substitution polymerizations that produce high molecular weight polymers in an easy manner. Due to the low volatility of ionic liquids and their wide liquid range, the present invention overcomes the disadvantages associated with the use of traditional organic solvents. For example, the ionic liquid solvent is present in the liquid phase at the temperature required for the reaction, and thus overcomes the problems associated with the use of high pressures and temperatures. The ionic liquid solvent also remains in the liquid phase at the lower temperatures required for isolation of the product polymer, resulting in relatively easy solvent isolation.

One embodiment of the method of the present invention comprises: providing at least a portion of the first component (e.g., dihalide monomer) and a portion of the second component (e.g., diphenolic monomer) to a portion of the ionic liquid and forming a pre-reaction mixture; providing heat and agitation to the pre-reaction mixture during a time sufficient to allow sufficient reaction of the first and second components and separating the polymeric material.

The dihalide monomer used in the present invention is typically of the formula X-R¹-[C(O)-R²]_n-Y or X-R¹-S(O)₂-R²-Y, wherein;

x and Y are independently selected from F, Cl, Br and I. Preferably, X and Y are the same and are Cl or F. Most preferably X and Y are F.

R¹And R²Is an aryl group. Optionally, the aryl group is optionally further optionally substitutedPhenylene substituted with one or more groups selected from alkyl or halogen.

n is 1 or 2. Preferably n is 1.

X and Y are each attached to the radical R at any permissible position¹And R². At R¹And R²In the case of phenylene, X and Y may each be independently attached at the ortho, meta or para positions of the benzene ring. Preferably X and Y are each attached in the para position of the phenyl ring.

In a preferred embodiment, R¹And R²Is unsubstituted phenylene, X and Y are Cl or F and n is 1. More preferably, the dihalide monomer used in the present invention is selected from 4, 4 '-difluorobenzophenone, 4' -dichlorobenzophenone or bis (4-chlorophenyl) sulfone. Most preferably, the dihalide monomer is 4, 4' -difluorobenzophenone.

The diphenolic monomers used in the present invention are selected from compounds having two phenolic OH groups. The diphenolic monomers typically have the general formula HO-Ar-OH, wherein Ar is an aryl group that may contain up to three phenyl groups connected by a carbonyl functionality. For example, in one embodiment, Ar is-Ph-C (O) -Ph-and the product formed is PEKK. In another embodiment Ar is phenylene. The OH group can be attached to the aryl group at any permissible position. For example, in the case where Ar is phenylene, the OH groups may be ortho-, meta-or para-substituted on the phenyl ring relative to each other. Optionally, the diphenolic monomer is selected from hydroquinone (1, 4-benzenediol), resorcinol (1, 3-benzenediol), pyrocatechol (1, 2-benzenediol), or bisphenol a. Most preferably the diphenolic monomer is hydroquinone.

Another embodiment of the method of the invention comprises: providing a first component (e.g., a monophenolic monohalide monomer) to a portion of the ionic liquid and forming a pre-reaction mixture; heat and agitation are provided to the pre-reaction mixture during a time sufficient to allow sufficient reaction of the first component and the polymeric material is isolated.

Monophenols for use in the present inventionThe monohalide monomer typically has the formula X-R¹-[C(O)-R²]_n-OH or X-R¹-S(O)₂-R²-OH, wherein

X is selected from F, Cl, Br and I. Preferably, X is Cl or F. Most preferably, X is F.

R¹And R²Is an aryl group. Optionally, aryl is phenylene optionally further substituted with one or more groups selected from alkyl or halogen.

n is 1 or 2. Preferably n is 1.

X and OH are each attached to the radical R at any permissible position¹And R². At R¹And R²In the case of phenylene, X and OH may each be independently attached to the benzene ring at the ortho, meta or para positions. Preferably X and OH are each attached in the para position of the phenyl ring.

In a preferred embodiment, R¹And R²Is unsubstituted phenylene and X is F. More preferably, the monophenol monohalide monomer used in the present invention is 4-fluoro-4' -hydroxybenzophenone.

In one embodiment, a base is provided to the ionic liquid. For example, a base is provided to the ionic liquid along with the monomers to form a pre-reaction mixture. Typical bases used in the process of the invention are metal carbonates, bicarbonates or hydroxides. The metal cation of the metal carbonate may be selected from: rubidium, cesium, lithium, sodium or potassium. Preferred bases for use in the present invention are potassium carbonate and sodium carbonate.

The metal carbonate base used in the reaction and the byproduct metal salt produced in the reaction have improved solubility in the ionic liquid solvent used in the present invention. Thus, the use of an ionic liquid enables the use of the cheaper base sodium carbonate rather than the more expensive potassium carbonate. In addition, because the byproduct metal salts, e.g., potassium fluoride or sodium fluoride, produced are soluble in the ionic liquid and, therefore, do not contaminate the polymer product, the purity of the final product polymer is increased.

In some embodiments, the disclosure herein provides methods for conducting nucleophilic aromatic substitution reactions in ionic liquids and forming polymeric materials selected from polyetherketone and polyethersulfone polymers.

Polyetherketone polymers are a class of polymers whose repeating units each contain at least one ether and at least one ketone functional group. In one embodiment, the polymer repeat unit contains one ether and one ketone functional group. An example of such a polymer is PEK having the structure shown below:

optionally, the polymer repeat unit contains one ether and two ketone functionalities. An example of such a polymer is PEKK having the structure shown below:

preferably the polyetherketone polymer repeat units contain two ether and one ketone functional group. An example of such a polymer is PEEK, the structure of which is given below.

Polyethersulfone polymers are a class of polymers whose repeating units each contain at least one ether and at least one sulfonyl functionality. In one embodiment, the repeat unit contains one ether and one sulfonyl functionality. An example of such a polymer is PES, the structure of which is given below:

in another embodiment, the repeat unit contains two ether and one sulfonyl functionality. An example of such a polymer is PS, the structure of which is given below;

details of the preparation and use of PS are given in j.e.harris, Engineering Thermoplastics (Engineering Thermoplastics), marcel dekker 1985j.m. margolis editions, page 177 ff.

In some embodiments, the disclosure herein provides methods for conducting nucleophilic aromatic substitution reactions in ionic liquids and forming the polymeric material PEEK.

In some embodiments, the disclosure herein relates to the use of ionic liquids as solvents for the synthesis of PEEK by either solution or suspension polymerization.

In some embodiments, the disclosure herein relates to polymers (based on spectroscopic methods, e.g., NMR, IR, DSC) prepared in diphenyl sulfone with an ionic liquid and starting with hydroquinone and 4, 4' -difluorobenzophenone that are substantially identical in character.

Ionic liquids or low temperature molten salts are known in the art as very low volatility solvents suitable for carrying out a range of chemical processes. However, it has not previously been disclosed that ionic liquids can be used as solvents for carrying out polymeric nucleophilic aromatic substitution reactions, particularly in the synthesis of PEEK. Ionic liquids particularly useful in the present invention are those comprising nitrogen-containing heterocyclic cations. Possible ionic liquids are, for example, bis (trifluoromethanesulfonyl) imide 1-butyl-1-methyl-azepaneDicyandiamide 1-butyl-1-methyl-azepaneBis (trifluoromethanesulfonyl) imide 6-nitrogenSpiro [5, 6 ]]Dodecane; dicyandiamide 6-nitrogenSpiro [5, 6 ]]Dodecane; chlorinated 1-benzyl-3-methylimidazoleBis (trifluoromethanesulfonyl) imide 1-butyl-1, 3-dimethylpiperidineDicyandiamide 1-butyl-1, 3-dimethylpiperidineBis (trifluoromethanesulfonyl) imide 1-butyl-3-methylimidazoleChlorinated 1-hexyl-3-methylimidazoleBis (trifluoromethanesulfonyl) imide 1-ethyl-3-methylimidazoleTetrafluoroboric acid 1-butyl-3-methylimidazoleAcetic acid 1-ethyl-3-methylimidazoleThiocyanic acid 1-ethyl-3-methylimidazoleEthyl sulfate 1-ethyl-3-methylimidazoleAnd N, N-dimethylethanolamine acetate. Preferably the ionic liquid is bis (trifluoromethanesulfonyl) imide 1-butyl-3-methylimidazole

In some embodiments, the disclosure herein relates to the use of ionic liquids as solvents to synthesize PEEK by solution polymerization or suspension polymerization, and the ionic liquids used are those disclosed in and known from united states published patent application 2008/0296531a1 (published on 04/12/2008) to Whiston et al; the disclosure is incorporated herein by reference in its entirety, for example, bis (trifluoromethanesulfonyl) imide 1-butyl-1-methyl-azepaneDicyandiamide 1-butyl-1-methyl-azepaneBis (trifluoromethanesulfonyl) imide 6-nitrogenSpiro [5, 6 ]]Dodecane; dicyandiamide 6-nitrogenSpiro [5, 6 ]]Dodecane; bis (trifluoromethanesulfonyl) imide 1-butyl-1, 3-dimethylpiperidineAnd dicyandiamide 1-butyl-1, 3-dimethylpiperidine

In some embodiments, the disclosure herein relates to polyethersulfone synthesis and the use of ionic liquids.

In one embodiment, a monofunctional monomer is provided to the ionic liquid along with other reactants to form a pre-reaction mixture. Unlike dihalide, diphenol and monophenol monohalide monomers, monofunctional monomers have only one reactive group and are thus chain limiting additives used to introduce chain end groups in polymer synthesis. Suitable monofunctional monomers are therefore phenol and aryl monohalides such as 4-fluorobenzophenone or 4-chlorobenzophenone.

In another embodiment, the multifunctional monomer is provided to the ionic liquid with other reactants to form a pre-reaction mixture. Unlike dihalide, diphenol and monophenol monohalide monomers, polyfunctional monomers have more than two reactive groups and are thus chain branching agents used to introduce chain branching into polymer synthesis. Suitable polyfunctional monomers are therefore trihydroxybenzene and trihalobenzene species.

Brief Description of Drawings

Fig. 1 shows NMR spectra of PEEK samples prepared according to the methods of comparative example 1 and example 1.

Fig. 2 shows the diffuse reflectance FT IR spectra of PEEK samples prepared according to the methods of comparative example 1 and example 1.

FIG. 3 graphically illustrates the results of Differential Scanning Calorimetry (DSC) testing of the PEEK material of comparative example 1.

FIG. 4 graphically illustrates DSC results for the PEEK material of example 1.

FIG. 5 shows heating rate at 5 ℃ per minute at N₂Thermo-gravimetric analysis (TGA) results of the flow down. Temperatures in degrees celsius appear on the x-axis and percentages of the initial weight appear on the y-axis. The solid line curve gives the results for PEEK prepared by the method of example 1. Curve given by dotted lineThe results for PEEK prepared by the method of comparative example 1 using diphenyl sulfone are presented.

Detailed description of the invention

Although the following detailed description contains many specifics for the purpose of illustration, those skilled in the art will appreciate that many variations and modifications of the following details are within the scope of the invention.

Thus, the following embodiments of the invention are set forth without any loss of generality to, and without imposing limitations upon, the claimed invention. Before the present disclosure is described in greater detail, it is to be understood that this disclosure is not limited to particular embodiments described, as such may, of course, vary. It is also to be understood that the terminology used herein is used for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present disclosure will be limited only by the appended claims.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present disclosure, the preferred methods and materials are now described.

All publications and patents cited in this specification are herein incorporated by reference as if each individual publication or patent were specifically and individually indicated to be incorporated by reference and were incorporated herein by reference to disclose and describe the methods and/or materials in connection with which the publications were cited. The citation of any publication is for its disclosure prior to the filing date and should not be construed as an admission that the present invention is not entitled to antedate such publication by virtue of prior disclosure. Further, the dates of publication provided may be different from the actual publication dates which need to be independently confirmed.

As will be apparent to those of skill in the art upon reading this disclosure, each of the individual embodiments described and illustrated herein has discrete components and features that can be readily separated from or combined with the features of the other several embodiments without departing from the scope or spirit of the present disclosure. Any described method may be performed in the order of events described or in any other order that is logically possible.

Embodiments of the present disclosure will employ, unless otherwise indicated, techniques of chemistry, polymer chemistry, and the like, which are within the knowledge of one of ordinary skill in the art. These techniques are fully described in the literature.

The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how the methods disclosed and claimed herein can be performed, and how the compositions and compounds disclosed and claimed herein can be used. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.) but some errors and deviations should be accounted for. Unless otherwise indicated herein, the term "a" or "an" is used interchangeably,

the parts are as follows by weight,

the temperature is in DEG C, and

pressure is in units of atmospheric pressure.

The standard temperature and pressure are defined as 25 ℃ and 1 atmosphere.

Before the embodiments of the present disclosure are described in detail, it is to be understood that this disclosure is not limited to particular materials, reagents, reaction materials, manufacturing processes, etc., as such may, unless otherwise specified, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting. It is also possible in the present disclosure that the steps may be performed in a different order, where logically possible.

As used herein, for both the specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a support" includes a plurality of supports. In this specification and in the claims that follow, reference will be made to a number of terms that shall be defined to have the following meanings unless a contrary intention is apparent.

Definition and testing method

Ionic liquids are liquids that contain substantially only ions, i.e., molten salts, although some ionic liquids are in dynamic equilibrium, with the majority of the liquid being composed of ions rather than molecular species. In the art, the term "ionic liquid" is used to refer to such salts having a melting point below 100 ℃. Such ionic liquids are sometimes also referred to as Room Temperature Ionic Liquids (RTILs). Ionic liquids are typically salts of bulky and unsymmetrical organic cations. For example, US7,157,588 teaches compositions based on N-substituted pyrrolidones with pendant ammonium cations separated from the pyrrolidone ring by alkyl spacers of different lengths. WO 2006/136529 teaches pyrazoles alkylsulfatesAnd a process for their preparation. WO 2008/150842 describes a broad class of ionic liquids containing heterocyclic nitrogen-containing cations.

The term "ionic liquid" as used in the context of the present invention refers to a salt having a melting point below about 100 ℃. Optionally, the ionic liquid used in the present invention comprises an organic cation. The organic cation is a cation containing at least one carbon atom. Typically, the organic cation contains at least one alkyl group. Conveniently, the ionic liquid comprises an asymmetric organic nitrogen-containing cation. In one aspect, the ionic liquid used in the present invention comprises an organic anion. The organic anion is an anion containing at least one carbon atom. Typically, the organic anion is an anion containing at least one carbon atom, but does not include a carbonate anion or a bicarbonate anion. On the other hand, the ionic liquid used in the present invention includes an organic cation and an organic anion, wherein the organic cation and anion are the same as defined above.

The process of the invention may use a single ionic liquid or a mixture of two or more ionic liquids. Typically, one or two, typically only one, ionic liquid is used.

Thus in one embodiment the ionic liquid comprises one or more cations selected from: 1-alkylpyridines(N-alkylpyridines)) (ii) a Alkyl-or polyalkyl-pyridinesAlkyl-or polyalkyl-guanidinium salts (especially tetraalkylguanidinium salts); imidazoleAlkyl-or polyalkyl-imidazoles(especially 1, 3-dialkylimidazoles)) (ii) a Ammonium (NR)₄ ⁺) Alkyl-or polyalkyl-ammonium (especially tetraalkylammonium); alkyl-or polyalkyl-pyrazolesAlkyl-or polyalkyl-pyrrolidines(especially dialkylpyrrolidines)) (ii) a Alkyl-or polyalkyl-piperidines(especially 3-methylpiperidine)) (ii) a Alkyl-or polyalkyl-azepaneAlkyl or polyalkyl-azaAlkyl oxygenAnd alkyl sulfonium. Each R group of the ammonium cation may be independently selected from: hydrogen, hydroxyl, alkyl ether, alkyl ester, alkyl amide, alkyl carboxylic acid, aryl or sulfonate. Examples include N-ethylpyridineN-methyl-N-alkylpyrrolidineSuch as N-butyl-N-methylpyrrolidineN-methyl-N- (butyl-4-sulfonic acid) pyrrolidine1-alkyl-3-alkylimidazolesSuch as 1-butyl-3-methylimidazole(BMIM; also known as N-methyl-N' -butylimidazole)) (ii) a 1-alkyl-3-arylimidazolesSuch as 1-methyl-3-benzylImidazole1-methyl-3-ethylimidazoleAnd trimethyl- (2-hydroxyethyl) ammonium.

A variety of different anions can be employed, including inorganic anions and macro-organic anions. In one embodiment, the anion of the one or more ionic liquids is selected from one or more of the following: halides (conveniently chloride, bromide or iodide), nitrates, alkyl-or alkyl-polyalkoxysulfonates, hydrogen sulfonates, hexafluorophosphates and tetrafluoroborates, and other anions based on nitrogen, phosphorus, sulfur, boron, silicon, selenium, tellurium, halogens, and oxyanions of metals. Suitable anions include, but are not limited to, tetrafluoroborate (BF)₄ ^-) Bis (trifluoromethanesulfonyl) imide (NTf)₂ ^-) Hydrogen Sulfate (HSO)₄ ^-) Mesylate, triflate, methoxyethylsulfonate, 2-methoxyethylsulfonate, ethoxyethanesulfonate, 2-ethoxyethanesulfonate, (methoxypropoxy) propylsulfonate, 1- (1-methoxypropoxy) -propylsulfonate, (methoxyethoxy) -ethanesulfonate, 1- (1-methoxyethoxy) -ethanesulfonate, methyl (diethoxy) ethanesulfonate, 1-methyl (diethoxy) ethanesulfonate, toluene-4-sulfonate, trifluoromethanesulfonyl, carboxylate, formate, acetate, carbonate, bicarbonate, dicyanimide, trifluoroacetate, and bis (trifluoromethanesulfonyl) imide.

The process of the present invention comprises providing heat to the pre-reaction mixture during a time sufficient to allow sufficient reaction of the monomer components. The temperature and time required for the monomer components to react sufficiently will be readily apparent to those skilled in the art of polymer chemistry.

Typical temperatures for this reaction range from 150 ℃ to 400 ℃. Optionally, the reaction is carried out at a temperature in the range of 200 ℃ to 400 ℃. Conveniently, a temperature in the range of 250 ℃ to 350 ℃ is used. In one embodiment, during the course of the reaction, the temperature is raised, in stages, or continuously, to a level such that the final polymer is in solution at any intermediate stage. Optionally the reaction temperature may be started at 200 ℃ and subsequently increased to 250 ℃, optionally after a set period of time or as required by the solubility of the polymer formed at those temperatures, it is further increased to 320 ℃.

Typically the time sufficient to allow sufficient reaction of the monomers is at least 1 hour, optionally at least 2 hours, optionally at least 3 hours, optionally at least 4 hours.

As mentioned above, the reaction may be carried out at different temperatures for different periods of time. In one embodiment, the reaction may be carried out at 200 ℃ for 2 hours and then the temperature is raised to 250 ℃ for another 2 hours. Optionally, the reaction is carried out at 200 ℃ for 1 hour, 250 ℃ for another 1 hour and then at 320 ℃ for another 1 hour.

When a product Relative Viscosity (RV) of at least 1.05 is reached, adequate reaction of the monomer components is evident. In one embodiment, adequate reaction of the monomer components is evident when the product has an RV of at least 1.1, 1.2, 1.3, 1.4, or 1.5.

As used herein, the term aryl means a carbocyclic aromatic group, such as phenyl or naphthyl (optionally phenyl).

The aryl group may be substituted with more than one substituent, where possible substituents include: an alkyl group; an aryl group; arylalkyl (e.g., substituted and unsubstituted benzyl, including alkylbenzyl); halogen atoms and halogen-containing groups such as haloalkyl (e.g. trifluoromethyl) or haloaryl (e.g. chlorophenyl); a hydroxyl group; carboxy (e.g., carboxaldehyde, alkyl-or aryl-carbonyl, carboxy, carboxyalkyl or carboxyaryl); amides and nitriles. Optionally aryl is unsubstituted.

The Relative Viscosity (RV) was measured as follows: 1g of polymer was dissolved in 100cm³96-In 98% sulfuric acid (1.84 g/cm)³Density of (d). The flow time t of the freshly prepared solution through a U-tube viscometer is measured at 25 DEG.C_s. The flow time t of the sulfuric acid solvent was similarly measured_o(ideally about 120 seconds flow time). From RV ═ t_s/t_oThe RV is calculated.

Characterization of polymer solutions and particle dispersions is well known to those skilled in the art. As used herein, Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) is a technique to collect and analyze scattered IR energy. DRIFTS is used for the measurement of fine particles and powders and is not difficult because no sample preparation sampling is required. As known to those skilled in the art, the IR beam enters the sample and either reflects off the surface of the particle or transmits through the particle. The IR energy reflected off of the surface is typically lost. An IR beam passing through a particle may either be reflected off or transmitted through the next particle. This transmission-reflection event can occur multiple times in the sample, increasing the optical path length. The scattered IR energy is finally collected by a spherical mirror focused on the detector. As a result, the detected IR light partially absorbed by the particles of the sample contains sample information.

Differential Scanning Calorimetry (DSC) is a thermal analysis technique used herein to quantify the difference between the amount of heat required to increase the temperature of a sample and a reference as a function of temperature. As known to those skilled in the art, both the sample and the reference are maintained at approximately the same temperature throughout the experiment. The temperature program used for DSC analysis causes the sample holder temperature to increase linearly as a function of time. The reference sample should have a well-defined heat capacity over the temperature range to be scanned. Here, and as known to those skilled in the art, DSC can be applied to polymer phase transitions involving energy changes or heat capacity changes, such as melting, glass transition, or exothermic decomposition.

Nuclear magnetic resonance spectroscopy (NMR) is a spectroscopic technique well known to those skilled in the art and is used herein to characterize the polymers prepared herein. Both FT-NMR and conventional techniques may be employed in the teachings of the present disclosure.

Thermogravimetric analysis, or TGA, is a thermal analysis technique used herein to quantify the relationship between changes in polymer weight and changes in temperature. As known to those skilled in the art, these analyses rely on the high accuracy of the following three measurements: weight, temperature and temperature variations. TGA as used herein is commonly used in studies and tests to determine specific characteristics of polymers, such as their degradation temperature, moisture uptake, levels of inorganic and organic components in materials, and solvent residues.

Examples

The following examples are provided to illustrate the present invention. The examples are not intended to limit the scope of the invention and should not be so interpreted.

It should be noted that ratios, concentrations, amounts, and other numerical data may be expressed herein in a range format. It is to be understood that such range format is used for convenience and brevity, and thus, should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a concentration range of "about 0.1% to about 5%" should be interpreted as: not only are concentrations of about 0.1% to about 5% by weight specifically mentioned included, but individual concentrations (e.g., 1%, 2%, 3%, and 4%) and subranges (e.g., 0.5%, 1.1%, 2.2%, 3.3%, and 4.4%) within the indicated ranges are also included. The term "about" can include ± 1%, ± 2%, ± 3%, ± 4%, ± 5%, ± 8% or ± 10% of the modified value or values. Further, the phrase "about 'x' to 'y'" includes "about 'x' to about 'y'".

Example 1

Hydroquinone (1.691g, 15.3) was purged by vacuum/nitrogen recycle using Schlenk line6mmol), 4-difluorobenzophenone (3.347g, 15.34mmol), ground potassium carbonate (2.144g, 15.51mmol) and the ionic liquid bis { (trifluoromethyl) sulfonyl } amine 1-butyl-3-methylimidazole(15 mL). The mixture was stirred under a nitrogen atmosphere and heated at 200 ℃ for 1 hour, and then at 250 ℃ for another 1 hour and finally at 320 ℃ for another 1 hour. The resulting brown slurry was cooled to room temperature and mixed with acetone (40 mL). The resulting suspension was stirred vigorously. The resulting product powder was collected by filtration, washed with water (3 × 20mL), and then with an acetone/methanol mixture (1: 1 by weight, 3 × 20 mL). The product was next dried under a stream of air and then dried under high vacuum at 140 ℃ for 12h to give a brown solid (3.684g, 83%). The product was characterized by Differential Scanning Calorimetry (DSC) under a nitrogen atmosphere at a 10 ℃/minute heating/cooling rate, and the melting point was obtained as the exothermic peak in the second heating cycle (m.p. ═ 326 ℃). The relative viscosity (RV ═ 1.44) was measured in a viscometer of the D' type as a solution in sulfuric acid (1% by weight). The product is also passed through¹H n.m.r. in D as solvent₂SO₄And analyzed using diffuse reflectance FT-IR.

Example 2

A mixture of hydroquinone (1.652g, 15.00mmol), 4-difluorobenzophenone (3.273g, 15.00mmol) and ground potassium carbonate (2.103g, 15.22mmol) in the ionic liquid bis { (trifluoromethyl) sulfonyl } amine 1-butyl-3-methylimidazole as solvent was reacted as in example 1(15 mL). The reaction was carried out at a temperature of 200 ℃ for 2 hours and then at 250 ℃ for another 2 hours. The resulting white reaction product slurry was then treated the same as in example 1 to give a white solid (4.090g, 95% yield). The product was characterized identically to that in example 1 (m.p. ═ 329 ℃, rv. ═ 1.32).

Example 3

A mixture of hydroquinone (1.003g, 10.02mmol), 4-dichlorobenzophenone (2.517g, 10.02mmol) and ground potassium carbonate (1.399g, 10.12mmol) was reacted in the same manner as in example 1 with ionic liquid bis { (trifluoromethyl) sulfonyl } amine 1-butyl-3-methylimidazole as solvent(10 mL). The resulting brown product slurry was then treated the same as in example 1 to give a white solid (2.150g, 74% yield). The product was characterized as in example 1 (RV ═ 1.23).

The 1H NMR, ftir (drift), DSC and TGA data for example 1 and comparative example 1 are compared in figures 1, 2, 3, 4 and 5. They demonstrate similar properties of the products formed using either method.

Comparative example 1

A mixture of hydroquinone (1.106g, 10.04mmol), 4-difluoro-benzophenone (2.192g, 10.05mmol) and ground potassium carbonate (1.400g, 10.13mmol) was reacted as in example 1 but with diphenyl sulfone (6.09g) as solvent. The gray solid mixture thus obtained was crushed at 100-120 ℃ and then cooled with liquid nitrogen and ground into a fine powder, which was then treated in the same manner as the post-treatment in example 1 to give a gray solid (2.775g, 96%). The product was characterized identically to that in example 1 (m.p. ═ 335 ℃, rv.: 2.48).

Comparative example 2

A mixture of hydroquinone (1.100g, 9.990mmol), 4-dichloro-benzophenone (2.510g, 10.00mmol) and ground potassium carbonate (1.490g, 10.78mmol) was reacted as in example 1, but using diphenylsulfone (7.02g) as the solvent. The grey solid mixture was then treated the same as in the work-up in example 4 to give a grey solid (2.785g, 97%). The product was characterized identically to that in example 1 (m.p.: 328 ℃, RV ═ 2.00).

Comparative examples 1 and 2 were carried out according to the disclosure of European patent document EP 0001879B 2 (published under the name ICI Ltd., 1989-11-23).

Many variations and modifications may be made to the above-described embodiments. It is intended to include all such modifications and alterations herein within the scope of this disclosure, and to be protected by the following claims.

Claims (20)

1. Use of an ionic liquid as a solvent in a nucleophilic aromatic substitution reaction to form a polymeric material, wherein the polymeric material is selected from polyetherketone and polyethersulfone polymers.

2. Use according to claim 1, wherein the nucleophilic aromatic substitution reaction comprises the steps of:

providing at least a portion of the first component and a portion of the second component to a portion of the ionic liquid to form a pre-reaction mixture;

providing heat and agitation to the pre-reaction mixture for a time sufficient to allow the components to react sufficiently, and separating the polymeric material.

3. The use of claim 2, wherein the first component comprises a dihalide monomer and the second component comprises a diphenolic monomer.

4. Use according to claim 1, wherein the nucleophilic aromatic substitution reaction comprises the steps of:

providing at least a portion of the components comprising the monophenolic monohalide monomer to a portion of the ionic liquid and forming a pre-reaction mixture;

providing heat and agitation to the pre-reaction mixture for a time sufficient to allow sufficient reaction of the monomer components, and separating the polymeric material.

5. Use according to any one of claims 3 to 4, wherein a base is provided into the ionic liquid together with the monomer.

6. Use according to claim 1, wherein the polymeric material is selected from PEEK, PEK, PEKK, PES or PS.

7. Use according to claim 6, wherein the polymeric material is PEEK.

8. Use according to claim 2, wherein a monofunctional monomer is provided to the ionic liquid to form the pre-reaction mixture.

9. Use according to claim 2, wherein a multifunctional monomer is provided into the ionic liquid to form the pre-reaction mixture.

10. A method of conducting a nucleophilic aromatic substitution reaction in an ionic liquid and forming a polymeric material, the method comprising contacting reactants in an ionic liquid, wherein the polymeric material is selected from polyetherketone and polyethersulfone polymers.

11. The method of claim 10, wherein the reactants comprise a portion of the first component and a portion of the second component, and these components are provided to a portion of the ionic liquid to form a pre-reaction mixture.

12. The method of claim 11, wherein the first component comprises a dihalide monomer and the second component comprises a diphenolic monomer.

13. The method of claim 10, wherein the reactants comprise a portion of the monophenolic monohalide monomer provided to a portion of the ionic liquid to form the pre-reaction mixture.

14. The method of any one of claims 11 to 12, wherein performing the nucleophilic aromatic substitution reaction comprises:

providing heat and agitation to the pre-reaction mixture for a time sufficient to allow the components to react sufficiently, and separating the polymeric material.

15. The method of claim 13, wherein performing the nucleophilic aromatic substitution reaction comprises providing heat and agitation to the pre-reaction mixture for a time sufficient to allow the components to react sufficiently, and separating the polymeric material.

16. The method of any one of claims 12 to 13, wherein a base is provided into the ionic liquid with the monomer.

17. The method of claim 10, wherein the polymer material is selected from PEEK, PEK, PEKK, PES, or PS.

18. The method of claim 17, wherein the polymer material is PEEK.

19. The method of claim 11, wherein monofunctional monomers are provided to the ionic liquid along with other reactants to form the pre-reaction mixture.

20. The method of claim 11, wherein a multifunctional monomer is provided to the ionic liquid with other reactants to form the pre-reaction mixture.