MXPA98002737A - Procedure for polymerizing acrilonitr - Google Patents

Abstract

This invention relates to a process for polymerizing acrylonitrile, comprising: (A) forming a polymerizable mixture consisting of acrylonitrile monomer, solvent and a metal catalyst, (B) contacting said mixture with an initiator, which initiator is selected from among the group consisting of sulfonyl halides, halopropionitriles, substituted halopropionitriles in the form of mono-adducts derived from sulfonyl halides and acrylonitrile, monoadducts derived from substituted sulfonyl halides and monomers other than acrylonitrile, or polymers containing end groups derived from sulfonyl halides, halopropionitriles , substituted halopropionitriles in the form of monoadducts derived from sulfonyl halides and acrylonitrile, or monoadducts derived from substituted sulfonyl halides and monomers other than acrylonitrile, and (C) polymerizing said acrylonitrile monomer to form a polymer composed of acrylonitrile. In one embodiment, the polymerizable mixture of step (A) further consists of at least one polymerizable acrylonitrile chromonomer and the polymer formed during step (C) is a copolymer or a multicomponent copolymer composed of acrylonitrile and said at least one other polymerizable chromonomer.

Description

PROCEDURE FOR. POLYMERIZING ACRILONITRIL TECHNICAL FIELD This invention relates to a process for polymerizing acrylonitrile. More specifically, this invention relates to a process for preparing acrylonitrile polymers and to multicomponent copolymers and copolymers consisting of acrylonitrile and at least one other polymerizable comonomer. Background of the Invention It is known how to polymerize acrylonitrile using radical and anionic reactions. These reactions are, however, uncontrolled and techniques are not available to precisely control the polydispersity and molecular weight of the polymer product. It would be advantageous to have a polymerization process in which precise control of the molecular weight could be obtained and achieve a narrow polydispersity. Such a procedure could result in polymers exhibiting highly uniform and reproducible properties based on obtaining well-defined polymeric structures. These advantages are achieved with the present invention. SUMMARY OF THE INVENTION This invention relates to a process for polymerizing acrylonitrile, consisting of: (A) forming a polymerizable mixture consisting of acrylonitrile monomer, solvent and a metal catalyst; (B) contacting said mixture with an initiator, said initiator being selected from the group consisting of sulfonyl halides, halopropionitriles, substituted halopropionitriles in the form of monoadducts derived from sulfonyl halides and acrylonitrile, monoadducts derived from substituted sulfonyl halides and monomers other than acrylonitrile, or polymers containing end groups derived from sulfonyl halides, halopropionitriles, substituted halopropionitriles in the form of monoadducts derived from sulfonyl halides and acrylonitrile, or monoadducts derived from substituted sulfonyl halides and monomers other than acrylonitrile, and (C) polymerizing said acrylonitrile monomer to form a polymer composed of acrylonitrile. In one embodiment, the polymerizable mixture of step (A) further consists of at least one polymerizable comonomer other than acrylonitrile and the polymer formed during step (C) is a copolymer composed of acrylonitrile and said at least one other polymerizable comonomer. DESCRIPTION OF THE PREFERRED EMBODIMENTS The monomer that is polymerized according to the inventive process can be acrylonitrile alone or acrylonitrile in combination with one or more polymerizable comonomers other than acrylonitrile. The other polymerizable comonomer can be any monomer or combination of monomers that is copolymerizable with acrylonitrile monomer. These include acrylonitrile derivatives, acrylates, methacrylates, acrylamides, vinyl esters, vinyl ethers, vinyl amides, vinyl ketones, styrenes, halogen-containing monomers, ionic monomers, acid-containing monomers, base-containing monomers, olefins and mixtures of two or more of these. The copolymers produced by the process of the invention can be random or alternating copolymers, block copolymers, graft copolymers or multiblock copolymers. They may have a comonomer content of up to about 99 mole% and, in one embodiment, up to about 90 mole% and, in one embodiment, up to about 75 mole% and, in one embodiment, up to about 50 mole% and , in one embodiment, up to about 25 mol% and, in one embodiment, up to about 1 mol%. They can be straight chain or branched. In one embodiment, the polymer produced by the process of the invention is an acrylonitrile homopolymer. Acrylonitrile derivatives include alkyl-substituted acrylonitriles. Alkyl groups typically contain from 1 to about 20 carbon atoms and, in one embodiment, from 1 to about 10 carbon atoms and, in one embodiment, from 1 to about 5 carbon atoms. Examples include ethacrylonitrile and ethacrylonitrile. Acrylates include alkyl, aryl, and cyclic acrylates, such as methyl acrylate, ethyl acrylate, phenyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, isobornyl acrylate, and functional derivatives of these acrylates, such as acrylate. -hydroxyethyl, 2-chloroethyl acrylate and the like. These compounds typically contain from 1 to about 12 carbon atoms and, in one embodiment, from 1 to about 8 carbon atoms. Methyl acrylate and ethyl acrylate are preferred. The methacrylates include CLC- ^, aryl and cyclic alkyl methacrylates, such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, phenyl methacrylate, isobornyl methacrylate and functional derivatives of these methacrylates, such as 2-hydroxyethyl methacrylate, 2-chloroethyl methacrylate and the like. These compounds typically contain from 1 to about 12 carbon atoms and, in one embodiment, from 1 to about 8 carbon atoms. Methyl methacrylate is preferred. Acrylamides include acrylamide and its derivatives, including the N-substituted alkyl and aryl derivatives thereof. These include N-methylacrylamide, N, -dimethylacrylamide and the like. Vinyl esters include vinyl acetate, vinyl propionate, vinyl butyrate and the like, with vinyl acetate being preferred. Vinyl ethers include vinyl ethers having from 1 to about 8 carbon atoms, including ethyl vinyl ether, butyl vinyl ether, and the like. Vinyl amides include vinyl amides having from 1 to about 8 carbon atoms, including vinylpyrrolidone and the like. Vinyl ketones include vinyl ketones having from 1 to about 8 carbon atoms, including ethyl vinyl ketone, butyl vinyl ketone, and the like. Styrenes include styrene, indene and substituted styrenes represented by the formula CH-CHA wherein each of A, B, C, D, E and F is independently selected from hydrogen, Cx to C4 alkyl groups or alkoxy (especially methyl or methoxy groups), halogroups (especially chloro), thio, cyano, acid or ester groups carboxylic, or fluorinated alkyl having from 1 to about 4 carbon atoms. Halogen-containing monomers include vinyl chloride, vinyl bromide, vinyl fluoride, vinylidene chloride, vinylidene bromide, vinylidene fluoride, halogen-substituted propylene monomers and the like, with vinyl bromide and vinylidene chloride being preferred. . The ionic monomers include sodium vinylsulfonate, sodium styrene sulfonate, sodium methallylsulfonate, sodium acrylate, sodium methacrylate and the like, with sodium vinylsulfonate, sodium styrene sulfonate and sodium methallylsulfonate being preferred. Acid-containing monomers include acrylic acid, methacrylic acid, vinylsulfonic acid, itaconic acid and the like, with itaconic acid and vinylsulfonic acid being preferred. The base-containing monomers include vinylpyridine, N-aminoethylacrylamide, N-aminopropylacrylamide, N-aminoethyl acrylate, N-aminoethyl methacrylate and the like. Olefins include isoprene, butadiene, straight chain or branched C2 alpha olefins at about C8 such as ethylene, propylene, butylene, isobutylene, diisobutylene, 4-methylpentene-1, 1-butene, 1-hexene, 1-octene and the like , with ethylene, propylene and isobutylene 4-methylpentene-1, 1-butene, 1-hexene, 1-octene being preferred. The choice of comonomer or combination of comonomers depends on the properties that are desired for the resulting copolymer or multicomponent copolymer product. The selection of said comonomer (s) is within the knowledge of the art. For example, copolymers and multicomponent copolymers can be prepared with acrylonitrile, methacrylonitrile and styrene and / or indene, which are characterized by relatively high temperatures of thermal distortion and transition of the vitreous state. The multicomponent copolymers derived from acrylonitrile, methacrylonitrile and isobutylene generally have good flexibility. The multicomponent copolymers derived from acrylonitrile, methacrylonitrile and acrylates and / or methacrylates are characterized by higher processing properties. Multicomponent copolymers derived from acrylonitrile, methacrylonitrile, base containing monomers and / or hydroxyl group-containing monomers are usually characterized by good coloration. The multicomponent copolymers derived from acrylonitrile, methacrylonitrile and halogen-containing monomers generally have good flame resistance characteristics. The solvent can be any material that is solvent for the polymer, copolymer or multicomponent copolymer product prepared by the process of the invention. These include o-, m- or p-phenylenediamine, N-formylhexamethyleneimine, N-nitrosopiperidine, maleic anhydride, chloromaleic anhydride, succinic anhydride, acetic anhydride, citraconic anhydride, β-butyrolactone, dioxanone, p-dioxanedione, ethylene oxalate. , ethylene carbonate, propylene carbonate, 2-oxazolidone, l-methyl-2-pyridone, 1,5-dimethyl-2-pyrrolidone, e-caprolactam, dimethylformamide (DMF), dimethylthioformamide, N-methyl-β-cyanoethylformamide, cyanoacetic acid, α-cyanoacetamide, N-methylacetamide, N, N-diethylacetamide, dimethylacetamide (DMA), dimethylmethoxyacetamide, N, N-dimethyl-α, α-trifluoroacetamide, N, N-dimethylpropionamide, N, N, N ', N' -tetramethyloxamide, hydroxyacetonitrile, water, mixtures of water with protic and aprotic organic solvents, supercritical fluids, chloroacetonitrile, chloroaceto-nitrile / water, β-hydroxypropionitrile, malonitrile, fumaro-nitrile, succionitrile, adiponitrile , bis (2-cyanoethyl) ether, bis (2-cyanoethyl) sulfide, bis (4-cyanobutyl) sulfone, 1,3,3,5-tetracyanopentane, nitromethane / water (94: 6), 1, 1, 1-trichloro-3-nitro-2-propane, tri (2-cyanoethyl) nitromethane, 3,4-nitrophenyl, methylene dithiocyanate, trimethylene dithiocyanate, sulfoxide dimethylene (SODM), tetramethylene sulphoxide, dimethylsulphone, ethylmethylsulfone, 2-hydroxyethylmethylsulfone, ethylene-1,2-bis (ethylsulfone), dimethyl phosphite, diethyl phosphite, sulfuric acid, nitric acid, p-phenolsulfonic acid, chloride concentrated aqueous lithium, concentrated aqueous zinc chloride, concentrated aqueous aluminum perchlorate, concentrated aqueous sodium thiocyanate, concentrated aqueous calcium thiocyanate, molten quaternary ammonium salts and their aqueous solutions and mixtures of two or more of these. A preferred solvent is ethylene carbonate. The metal catalyst can be any metal catalyst that is capable of entering a redox reaction with the initiator. Useful metals include Cu, Pd, Ni, Fe, Co, Sm, Zr, Mo, Pt, Re, Mn, W, Ru and Rh, or a mixture of two or more of these, being especially preferred the Cu. In one embodiment, the catalyst consists of a mixture of Cu (I) and Cu (II). The metal, which is initially in salt form (for example, halide, especially chloride or bromide, cyanide, acetate, etc.), is used in combination with an organic ligand-forming material that forms complexes with the metal. Examples of the organic ligand-forming material include 2,2'-bipyridine and its derivatives, which derivatives include those which are disubstituted with alkyl groups, carboxylic ester groups, cyano groups or fluorinated alkyl groups of 1 to about 20 carbon atoms and , in one embodiment, about 1 to about 10 carbon atoms. Examples include 4,4'-dialkyl-2,2'-bipyridines, such as 4,4'-dimethyl-2,2'-bipyridine, 4,4 '-dinonyl-2,2'-bipyridine and the like , as well as 4, 4'-dicarboxylic ester-2, 2'-bipyridines. The initiator is a sulfonyl halide, halopropionitrile, substituted halopropionitrile in the form of a monoadduct derived from a sulfonyl halide and acrylonitrile or a monoadduct derived from a substituted sulfonyl halide and a monomer other than acrylonitrile. Sulfonyl halides include chlorides and sulfonyl bromides. The sulfonyl halides include substituted and unsubstituted arylsulfonyl halides, halogenated and non-halogenated aliphatic sulfonyl hydrocarbon halides, halogenated sulfonyl halides and polymers containing sulfonyl halides. Substituted arylsulfonyl halides include the alkyl- or alkoxy-substituted arylsul-fonyl halides, wherein the alkyl and alkoxy substituents typically have from 1 to about 20 carbon atoms and, in one embodiment, from 1 to about 10 carbon atoms. The halogenated aliphatic sulfonyl hydrocarbon halides are typically constituted by bromine or chlorine atoms and the aliphatic portion typically contains from 1 to about 20 carbon atoms and, in one embodiment, from 1 to about 10 carbon atoms. Examples of useful arylsulfonyl halides include: ortho-, meta- or para-methylbenzenesulfonyl chloride; ortho-, meta- or para-methoxybenzenesulfonyl chloride; ortho-, meta- or para-chlorobenzenesulfonyl chloride; ortho-, meta- or para-fluorobenzenesulfonyl chloride; ortho-, meta- or para-bromobenzenesulfonyl chloride; ortho-, meta- or para-carboxylic ester benzenesulfonyl chloride, and the like. Examples of the halogenated aliphatic sulfonyl hydrocarbon halides include trichloromethylsulfonyl chloride, trifluoromethylsulfonyl chloride, and the like. Examples of the halogenated sulfonyl halides include sulfuryl chloride. The monoadduct which is in the form of a substituted halopropionitrile is an adduct formed by the reaction of any of the aforementioned sulfonyl halides with acrylonitrile monomer. The monoadduct derived from a substituted sulfonyl halide and a monomer other than acrylonitrile is an adduct formed by the reaction of any of the aforementioned sulfonyl halides with any of the polymerizable comonomers other than acrylonitrile mentioned above. Examples of adducts include monoadducts formed by the reaction of any of the aforementioned sulfonyl halides with acrylonitrile, styrene, methyl methacrylate, methyl butyrate, vinyl acetate, ethylene and the like. In one embodiment, the initiator is a polymer containing final groups derived from any of the sulfonyl halides, halopropionitriles, substituted halopropionitriles in the form of monoadducts derived from sulfonyl halides and acrylonitrile or monoadducts derived from substituted sulfonyl halides and monomers other than acrylonitrile precedents An example of said polymer to which said final groups can be attached is polyphenylene oxide. In the practice of the present invention, the polymerization process is carried out in solution, emulsion, suspension or in bulk, as a single phase or multiple phases. The pressure can be atmospheric, subatmospheric (for example, only 0.1 mm Hg) or superatmospheric (for example, from about 1 to about 20 atmospheres). In one embodiment, the concentration of the solvent is relatively low. Mass polymerizations are particularly advantageous. The present invention can be practiced as a semi-continuous or continuous process. Initially, the acrylonitrile monomer, the polymerizable comonomer (s) (if any) and the metal catalyst are mixed with the solvent. The content of monomers (acrylonitrile monomer and polymerizable comonomer (s), if any) is typically from about 50% to about 90% by weight and, in one embodiment, about 55% by weight. about 80% by weight of the copolymerizable reaction mixture. The solvent content is from about 10% to about 50% by weight and, in one embodiment, from about 20% to about 45% by weight, of the polymerizable reaction mixture. The polymerizable reaction mixture is placed in a reaction vessel. The reaction vessel is purged with an inert gas, such as nitrogen, argon and the like. In one embodiment, the purge of inert gas is continued throughout the polymerization reaction. The polymerizable reaction mixture is heated to a temperature in the range of about 40 ° C to about 120 ° C and, in one embodiment, about 50 ° C to about 100 ° C. The temperature of the polymerization reaction is maintained in this range throughout the entire process. The initiator is added to the polymerizable reaction mixture to initiate the polymerization reaction. The initiator is typically added to the reaction vessel as a single solution. The initiator is added the principle to maintain the desired polymerization rate, which can be determined by those skilled in the art. The amount of initiator that is required is determined by the molecular weight of the polymer to be prepared. The ratio of the molar concentration of monomer to the molar concentration of initiator determined when the conversion is complete is the degree of polymerization of the resulting polymer. This degree of polymerization multiplied by the molecular weight of the monomers determines the molecular weight of the polymer. In an embodiment, the molar ratio of initiator to metallic catalyst is critical and this ratio is from about 1:10 to about 10: 1 and, in one embodiment, from about 1: 1 to about 1: 0.3. Simultaneously, then or preferably immediately after the polymerization reaction has been initiated, the monomer feed containing acrylonitrile monomer and polymerizable comonomer (if any) is added in increments or continuously to the polymerization reaction mixture in the reaction vessel. reaction. The combined weight of the unreacted acrylonitrile monomer and unreacted comonomer (if any) in the polymerization mixture at any time is generally not greater than about 10% by weight and, in one embodiment, is not greater than about 10% by weight. about 7% by weight and, in one embodiment, is not more than about 5% by weight based on the total weight of the polymerizer mixture. The molar ratio of the acrylonitrile monomer to the comonomer (s), if any, in the monomer feed is fixed and constant through the polymerization process, resulting in a homogeneous multi-component polymer, copolymer or copolymer. The polymer composition is essentially the same as the composition of the monomer feed. The polymerizing mixture is stirred continuously or intermittently by any known method, either stirring, shaking or the like. Preferably, the polymerization mixture is stirred continuously.

The reaction is continued until the polymerization has proceeded to the desired degree, generally from about 40% to about 90% conversion and, in one embodiment, from about 70% to about 95% conversion. The polymerization reaction is stopped by cooling, adding an inhibitor, such as diethylhydroxylamine, 4-methoxyphenol and the like, and discontinuing the monomer feed. At the conclusion of the polymerization reaction, the polymer product is separated from the reaction medium using known techniques. These include precipitation using non-solvents, coagulation by freezing, coagulation with salts, etc. An advantage of an embodiment of this invention is that the polymerization process can be carried out with a relatively low concentration of solvent and, therefore, the steps of the process for separating the polymer from the reaction medium are relatively simple and less expensive than with the techniques used in this field. The number average molecular weight, Mn, of the multi-component polymers, copolymers and copolymers produced by the process of the invention typically ranges from about 200 to about 6 million and, in one embodiment, from about 2,000 to about 1 million and, in one embodiment , between approximately 20,000 and approximately 200,000. The Mp / Mn ratio typically varies between about 1.01 and about 2.5 and, in one embodiment, between about 1.1 and about 1.3. An advantage of the process of the invention is that the molecular weight and the Mp / Mn ratio can be precisely controlled. The multicomponent polymer, copolymer or copolymer prepared by the process of the invention can be further processed by centrifugation, casting, extrusion and the like. Lubricants, dyes, bleaching agents, plasticizers, pseudoplasticizers, pigments, delustrants, stabilizers, static agents, antioxidants, reinforcing agents, fillers and the like can be combined with the polymer. These polymers can be used in numerous applications, such as for use as fibers, sheets, films, pipes, tubes, emptied articles and the like. The multicomponent polymers, copolymers and copolymers produced by the process of the invention provide the particular advantage of being useful in applications that require a high gas barrier and solvent resistance, such as packaging for food and oily products, solvent containers, coatings of plugs, protection of sensitive substances and retention of vital components and / or fragrances / odors. The temperature-controlled thermal distortion properties of these polymers allow their use in a variety of applications, including "hot-fill" and sterilization and electrical applications. The controlled clarity through the crystallinity and the control of the size of the crystal provide an added receptivity to these polymers. The higher hardness exhibited by these polymers enhances their use in the manufacture of parts of equipment and frames resistant to solvents. The greater crystallinity and orientation that can be achieved with these polymers are highly beneficial and make possible the manufacture of fibers and films with superior performance. Not wishing to be bound by any theory, we believe that the initiator used in the inventive process (eg, sulfonyl halide) creates an active species (radicals) that can initiate a controlled chain polymerization process. The role of the catalyst is to activate the initiator (that is, to reduce the activation energy of the initiation and, therefore, the temperature at which it is initiated). Conventional radical polymerizations are accompanied by chain termination and transfer reactions and, therefore, molecular weight can not be controlled, the polydispersity and the structure of the polymer end groups. With the present invention, on the other hand, the specific combination of initiator and catalyst employed solves these problems. In the first step of the initiation, the catalyst reduces the radical initiator (for example, the sulfonyl halide is reduced to a sulfonyl radical) through a redox process and, as a result, the catalyst is oxidized. The reduced initiator (eg, sulfonyl radical) can react with the monomer (eg, acrylonitrile monomer) or react with the oxidized catalyst to regenerate the starting radical initiator (eg, sulfonyl halide). This is a reversible procedure. This procedure of reversible creation and termination of radicals takes place not only during the initiation phase of the procedure, but also during the propagation phase of the process. This creates a reversible completion reaction. This completion reaction provides a rapid exchange between the active propagating radicals, which, in one embodiment, are extremely low in concentration, and the growing chains terminated in inactive halide. Under these circumstances, the propagating radicals react predominantly with the monomer (propagation) and end with the catalyst (reversible completion) and thus suppress conventional procedures of irreversible completion and chain transfer. When these conventional side reactions are eliminated, the polymerization process becomes controlled and, therefore, behaves like a polymerization process in vivo. The first requirement of a polymerization process in vivo requires a quantitative initiation reaction and, at the same time, an initiation reaction, which is faster than the propagation reaction. The second requirement is the absence of reactions of irreversible completion and chain transfer. Under these conditions, the molecular weight of the polymer can be designed in advance, since it is determined by the ratio between the concentration of the monomer and the initiator. Since the initiation is faster than the propagation and which is quantitative, the resulting polymer has one end of the chain derived from the radical part of the initiator and one end of the chain derived from the halide group of the initiator. If the radical initiator has two, three or more halide groups (for example, sulfonyl halide groups), the growth of the polymer can be in two, three or more directions and, as a result, star polymers, block copolymers can be formed , graft copolymers, polymers and branched and hyperbranched copolymers. The end of the polymer chain derived from the halide group can be used for the initiation of a second polymerization with a different monomer to obtain block copolymers or star block copolymers. The end of the polymer chain derived from the radical part of the initiator can be used for other reactions, including block copolymerizations. The following examples are given for the purpose of illustrating the invention. Unless otherwise indicated, in the following examples, as well as throughout the specification and claims, all parts and percentages are by weight, all temperatures are in degrees Celsius and all pressures are atmospheric. Example 1 The following ingredients are introduced successively into a 25 ml Schlenk tube equipped with magnetic stirrer and septum: 3.4 mg of CuBr, 8 mg of 2,2'-bipyridine and 2 ml of acrylonitrile (AN). 2 ml of ethylene carbonate (EC) are heated to 80 ° C and added to the mixture. The mixture is stirred for 5 min, after which 4 ml of 2-bromopropionitrile (BPN) is injected. The molar ratio of AN to BPN is 560/1. Oxygen is removed using four freeze-pump-thaw cycles. The polymerization is carried out at 60 ° C for 61 hours. The polymerization mixture is diluted with 2 ml of dimethylformamide (DMF). The polymer is precipitated by adding 5 ml of methanol and 5 ml of tetrahydrofuran (THF) to the Schlenk tube. The precipitate is filtered and dried to obtain 1 g of polyacrylonitrile (White bread. The conversion is 62%. The Mn is 30,000 and the Mp / Mp is 1.17 (per CPG in DMF at 40 ° C and using polyethylene glycol (PEG) standards). Example 2 The polymerization of Example 1 is repeated, except for the fact that the initiator is 2-chloropropium-nitrile (CPN) instead of BPN. The amounts used of materials are as follows: 11 mg of CuCl, 34 mg of 2,2'-bipyridine, 2 ml of AN, 1 ml of EC and 20 μl of 2-chloropro-pionitrile (NPC). The molar ratio of AN to CPN is 130/1.

After 2 hours at 100 ° C, the conversion is 56% (yield = 0.90 g). The Mn is 6,000 and Mp / Mn is 1.15 (per CPG in DMF at 40 ° C and using PEG standards). EXAMPLE 3 The polymerization of Example 1 is repeated, except for the fact that the initiator is p-methoxybenzenesulfonyl chloride (CMBS) instead of BPN and that the catalyst is CuCl / 2, 2'-bipyridine instead of CuBr / 2,2'-bipyridine. The molar ratio of AN to CMBS is 100/1. The molar ratio of CuCl to 2,2'-bipyridine is 1/2. The polymerization is carried out for 20 hours. The polymerization temperature and the CMBS / CuCl molar ratio vary as indicated below. The results are the following: Example 4 The polymerization of Example 1 is repeated except that the comonomer is polymerized with the AN and CMBS is used as the initiator in place of BPN. The comonomer is MA (methacrylate), E (styrene), MAM (methyl methacrylate) or MAN (methacrylonitrile), as indicated below. The molar ratio of AN to comonomer is 10.1 / 0.7. The molar ratio of CuBr to 2, 2'-bipyridine (bpi) is 0.5 / 1. The molar ratio of AN / CMBS / CuBr / bpi is 100/1 / 0.5 / 1. The polymerization is carried out for 16 hours at 100 ° C. The results are as follows: Having explained the invention in relation to its preferred embodiments, it is to be understood that various modifications thereof will be apparent to those skilled in the art upon reading the specification. Therefore, it is to be understood that the invention described herein is intended to cover such modifications insofar as they fall within the scope of the appended claims.

Claims (10)

1. CLAIMS 1. A process for polymerizing acrylonitrile, comprising: (A) forming a polymerizable mixture consisting of acrylonitrile monomer, solvent and a metal catalyst; (B) contacting said mixture with an initiator, said initiator being selected from the group consisting of sulfonyl halide, halopropionitrile, substituted halopropionitrile in monoadduct form derived from a sulfonyl halide and acrylonitrile, a monoadduct derived from a sulfonyl halide substituted and a monomer other than acrylonitrile, or polymers containing end groups derived from sulfonyl halides, halopropionitriles, substituted halopropionitriles in the form of monoadducts derived from sulfonyl halides and acrylonitrile, or monoadducts derived from substituted sulfonyl halides and monomers other than acrylonitrile; (C) polymerizing said acrylonitrile monomer to form a polymer composed of acrylonitrile. The method of claim 1, wherein said polymerizable mixture of step (A) further comprises at least one polymerizable comonomer other than acrylonitrile and the polymer formed in step (C) is a copolymer composed of acrylonitrile and at least one other polymerizable comonomer. 3. The process of claim 2, wherein said polymerizable comonomer is a derivative of acrylonitrile, acrylate, methacrylate, acrylamide, vinyl ester, vinyl ether, vinyl amide, vinyl ketone, styrene, halogen-containing monomer, ionic monomer, acid-containing monomer , monomer containing base, olefin or mixture of two or more of these. 4. The process of claim 2, wherein said polymerizable comonomer is selected from the group consisting of methyl acrylate, ethyl acrylate, methyl methacrylate, methacrylonitrile, vinyl acetate, styrene, ethylene, propylene, isobutylene, 4-methylpenteno- 1, 1-butene, 1-hexene, 1-octene and mixtures of two or more of these. The process of claim 1, wherein said solvent is selected from the group consisting of o-, m- or p-phenylenediamine, N-formylhexamethiinimine, N-nitrosopiperidine, maleic anhydride, chloromaleic anhydride, succinic anhydride, acetic anhydride , citraconic anhydride, β-butyrolactone, dioxanone, p-dioxanedione, ethylene oxalate, ethylene carbonate, propylene carbonate, 2-oxazolidone, 1-methyl-2-pyridone, 1,5-dimethyl-2-pyrrolidone, e- caprolactam, dimethylformamide (DMF), dimethylthioformamide, N-methyl-β-cyanoethylformamide, cyanoacetic acid, α-cyanoacetamide, N-methylacetamide, N, N-diethylacetamide, dimethylacetamide (DMA), dimethylmethoxyaceta ida, N, N-dimethyl- a, a, a-trifluoroacetamide, N, N-dimethylpropionamide, N, N, N ', N' -tetramethyloxamide, hydroxy-acetonitrile, water, mixtures of water with protic and aprotic organic solvents, supercritical fluids, chloroacetonitrile, chloroacetonitrile / water, ß-hydroxypropionitrile, malonitrile, fumaronitri lo, succionitrile, adiponitrile, bis (2-cyanoethyl) ether, bis (2-cyanoethyl) sulfide, bis (4-cyanobutyl) sulfone, 1,3,3,5-tetracyanopentane, nitromethano-water (94: 6) , 1, 1, l-trichloro-3-nitro-2-propane, tri (2-cyanoethyl) nitromethane, 3,4-nitrophenyl, methylene dithiocyanate, trimethylene dithiocyanate, dimethylene sulfoxide (SODM), tetramethylene sulfoxide, dimethylsulphone, ethylmethylsulfone, 2-hydroxyethylmethylsulfone, ethylene-1,2-bis (ethylsulfone), dimethyl phosphite, diethyl phosphite, sulfuric acid, nitric acid, p-phenolsulfonic acid, concentrated aqueous lithium chloride, concentrated aqueous zinc, concentrated aqueous aluminum perchlorate, concentrated aqueous sodium thiocyanate, concentrated aqueous calcium thiocyanate, molten quaternary ammonium salts and their aqueous solutions and mixtures of two or more of these. 6. The process of claim 1, wherein said solvent is ethylene carbonate. The method of claim 1, wherein said metal catalyst consists of Cu, Pd, Ni, Fe, Ru, Rh, Co, Sm, Zr, Mo, Re, Mn, or a mixture of two or more of these. The method of claim 1, wherein said metal catalyst is copper complexed with 2,2'-bipyridine or a derivative thereof. The method of claim 1, wherein said initiator is 2-bromopropionitrile, 2-chloropro-pionitrile, a monoadduct derived from a sulfonyl chloride and acrylonitrile, a monoadduct derived from a substituted sulfonyl chloride and a monomer other than acrylonitrile, an arylsulfonyl halide, a substituted arylsulfonyl halide, an aliphatic hydrocarbon halide, a halogenated sulfonyl halide or a non-halogenated aliphatic sulfonyl hydrocarbon halide. The process of claim 1, wherein said initiator is trichloromethylsulfonyl chloride, trifluoromethylsulfonyl chloride or sulfuryl chloride. SUMMARY OF THE INVENTION This invention relates to a process for polymerizing acrylonitrile, comprising: (A) forming a polymerizable mixture consisting of acrylonitrile monomer, solvent and a metal catalyst; (B) contacting said mixture with an initiator, the initiator of which is selected from the group consisting of sulfonyl halides, halopropionitriles, substituted halopropionitriles in the form of monoadducts derived from sulfonyl halides and acrylonitrile, monoadducts derived from substituted sulfonyl halides and monomers other than acrylonitrile; or polymers containing end groups derived from sulfonyl halides, halopropionitriles, substituted halopropionitriles in the form of monoadducts derived from sulfonyl halides and acrylonitrile, or monoadducts derived from substituted sulfonyl halides and monomers other than acrylonitrile, and (C) polymerizing said monomer from acrylonitrile to form a polymer composed of acrylonitrile. In one embodiment, the polymerizable mixture of step (A) further consists of at least one polymerizable comonomer other than acrylonitrile and the polymer formed during step (C) is a copolymer or multi-component copolymer composed of acrylonitrile and said at least one other polymerizable comonomer.