Nylon Composition

Abstract

The polyamide comprises a plurality of amide units forming a polymer chain and an alkyl substituent on the amide group. The polyamide has an amide unit substitution in the polymer chain in an amount between about 0.1% and about 10% of amide units. A method for forming a polyamide composition includes providing a polyamide comprising a plurality of amide groups in a backbone structure, and modifying a portion of the plurality of amide groups in the backbone structure with one or more alkyl substituents to form a polyamide composition. The polyamide has an amide unit substitution in the backbone in an amount between about 0.1% and about 10% of amide units.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to and benefit of U.S. Provisional Patent Application No. 63 / 310,758, filed February 16, 2022, and entitled "NYLON COMPOSITIONS," the entirety of which is incorporated herein by reference. [Background technology]

[0002] background

[0002] Nylon can be produced by polymerization of amide units, and the type of nylon produced can be designated by the number of carbon atoms in the monomer units polymerized. The presence of amide units can make nylon less stable than other types of polymers (e.g., polyethylene). Instability can include thermal instability, which can make nylon difficult to process. Summary of the Invention [Means for solving the problem]

[0003] overview

[0003] In some embodiments, polyamides include a plurality of amide units forming a polymer chain and alkyl substituents on the amide groups, the polyamides having an amide unit substitution in an amount of between about 0.1% and about 10% of the amide units in the polymer chain.

[0004] In some embodiments, the poly-2-pyrrolidone polymer has the formula: [ka] wherein m can be 3 and R includes an alkyl substituent on the amide group. wherein the poly-2-pyrrolidone has a substitution of amide units in an amount of between about 0.1% and about 10% amide units in the poly-2-pyrrolidone.

[0005]

[0005] In some embodiments, a method of forming a polyamide composition includes providing a polyamide, the polyamide including a plurality of amide groups in a backbone structure of the polyamide, and modifying a portion of the plurality of amide groups in the backbone structure with one or more alkyl substituents to form a polyamide composition, the polyamide having substitution of amide units in an amount between about 0.1% and about 10% amide units in the backbone.

[0006]

[0006] These and other features will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings and claims. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Detailed Description

[0007] Various nylons or polyamides can be modified to obtain useful polymers. For example, poly-2-pyrrolidone can be produced by alkali-catalyzed polymerization of 2-pyrrolidone in the presence of various compounds such as carbon dioxide. The resulting polymer may, in some circumstances, be referred to as nylon 4, based on the polymerization of monomers containing four carbon atoms. Further modifications can be used to change the properties of the polypyrrolidone (e.g., melting temperature, decomposition temperature, molecular weight, functionalization, etc.), and the resulting material can exhibit improved biodegradation compared to other polymers, such as olefin-based polymers such as polyethylene, polypropylene, etc. To the extent that it can be formed from degradable materials, the environmental persistence of such polymers can be reduced compared to other polymers.

[0008]

[0008] The resulting polypyrrolidone can be formed into various forms and products that allow for a variety of end uses, such as sheets, films, filaments, ribbons, molded articles, and fibers.Due to its hydrophilicity, which is very similar to cotton and silk, polypyrrolidone fibers have long been recognized as having great commercial potential.For example, fabrics made of polypyrrolidone, in contrast to other currently available synthetic fibers, are easily dyed like cotton, can be ironed at cotton temperature, dissipate static charge easily, and have the comfort of cotton, silk, and wool, among others.

[0009]

[0009] Biodegradability is balanced with the ability to form useful articles from the polymer. Filaments can be melt spun from the polymer by extrusion from a spinneret to form filaments and fibers. In melt spinning, the polymer composition is extruded in molten conditions, generally at a melt temperature above about 270°C. This extrusion must be done carefully, as thermal degradation of the polymer can cause the polymer to revert to monomers. This can also cause bubbles, and can form voids or poxmarks in the extrudate or filament, with substantial product loss and increased process costs. In addition to reverting to monomers, molecular weight degradation also occurs during melt spinning, resulting in poly-2-pyrrolidone filaments with substantially lower molecular weights than the original polymer. If the initial polymer molecular weight is too low, or if the molecular weight degradation is too severe, the molecular weight of the filament will be insufficient for the filament to have sufficient tensile strength and fibrillation properties.

[0010]

[0010] In addition to melt spinning, solution spinning is one of the methods for forming useful articles from polymers. When solution spinning is used, the polymer is dissolved in a solvent to a high concentration, commonly called a dope, and then extruded into a non-solvent where precipitation occurs to form the article. Typical concentrations of the dope solution can be between 2.5% and 50% by weight, resulting in high concentration solutions ranging from 1000 centipoise to 1,000,000 centipoise or more, most preferably 5000 centipoise to 50,000 centipoise. Examples of solvents that can be used are acids, polar protic solvents, polar aprotic solvents, ionic liquids, fluorinated alcohols, etc.

[0011]

[0011] A further problem is that higher molecular weight (e.g., above about 120,000) polymers are more thermally stable, but also more viscous, making them more difficult to extrude. If extrusion at a lower temperature is attempted to avoid thermal decomposition, the material does not melt properly and produces fibers with substantially lower tensile strength. Therefore, in order to efficiently melt extrude polypyrrolidone, the thermal stability of the polymer and / or the extrudability of the polymer composition can be improved.

[0012]

[0012] In some aspects, polypyrrolidones are disclosed herein that can reduce the melting temperature and / or increase the thermal stability, thereby improving the processability of the polymer. In some aspects, the disclosed methods and resulting polymers can reduce the melting point of the resulting polymer without affecting the decomposition temperature. Alternatively, it is possible to increase the decomposition temperature of the resulting polymer without affecting the melting point. This then allows the polymer to be more easily processed and molded into useful articles without degrading the polymer during the process.

[0013]

[0013] The present disclosure relates to various polyamide compositions that can be modified to improve processability while maintaining biodegradability. Although various nylons can be produced as provided herein, in some aspects, poly-2-pyrrolidone compositions modified to have improved thermal stability and methods of processing poly-2-pyrrolidone are described as examples. Other polyamides, such as nylon 3, nylon 4, nylon 6, proteins, and other types of nylons, such as nylon 2,2, nylon 3,3, etc., can also be modified as shown herein to improve properties such as lowering the melting point and / or increasing the decomposition temperature. In general, the modification techniques described herein can be used for any suitable polyamide.

[0014]

[0014] 2-pyrrolidone can be polymerized to form poly-2-pyrrolidone using any suitable technique. The polymerization method of 2-pyrrolidone to form poly-2-pyrrolidone (sometimes simply referred to herein as polypyrrolidone) can include polymerization of 2-pyrrolidone in the presence of an alkaline polymerization catalyst, optionally with an activator. Cationic ring-opening polymerization methods can also be used.

[0015] The polymer formed from 2-pyrrolidone has the structure: [ka] It is believed to be a linear polyamide that came to be known as nylon-4 having the formula: Here, n may range from about 200 to over 1,000,000, or in some embodiments may be as high as 100,000. In some embodiments, n may range as high as about 10,000 or as high as about 5000 depending on the type of nylon considered. More common formulations of nylons formed from common starting materials include: [ka] where when m is 1, the polyamide is nylon 2, when m is 2, the polyamide is nylon 3, and when m is 3, the polyamide is nylon 4, n can be any value previously described with respect to formula 1, and R can be hydrogen or another alkyl modification provided herein.

[0016]

[0016] In some embodiments, polypyrrolidone can be prepared by polymerizing 2-pyrrolidone with an alkaline polymerization catalyst in the presence of carbon dioxide (CO2). For example, polymerization can be carried out by bubbling CO2 through a mixture of 2-pyrrolidone and an alkali metal salt of 2-pyrrolidone, such as sodium or potassium pyrrolidonate, with the alkali metal pyrrolidonate acting as the alkaline polymerization catalyst. Polypyrrolidone can also be prepared by reacting CO2 with an alkali metal salt of 2-pyrrolidone to form an adduct of CO2 with the alkali metal pyrrolidonate, and then polymerizing the 2-pyrrolidone monomer in the presence of the adduct.

[0017]

[0017] In some embodiments, the polymerization of 2-pyrrolidone can be carried out using an alkaline polymerization catalyst in the presence of CO2. The 2-pyrrolidone monomer can be polymerized in the presence of an alkaline polymerization catalyst at a temperature between 18°C ​​and about 100°C, preferably between 25°C and 70°C, and most preferably between 25°C and 60°C, under pressures ranging from subatmospheric to superatmospheric. Bulk or suspension polymerization can be used.

[0018]

[0018] The alkaline polymerization catalyst may be any that is used in the polymerization of 2-pyrrolidone. Suitable alkaline polymerization catalysts are derivatives of alkali metals, such as hydroxides and oxides of alkali metals, for example potassium tert-butoxide. Alkaline metal alcoholates, such as sodium methylate, may also be used. In addition, oxides and hydroxides of alkaline earth metals, such as calcium and barium, may be used as catalysts. Also, organometallic compounds, preferably organometallic compounds that are strong bases, such as lithium, potassium, and sodium alkyls, such as butyl lithium, and aryls of alkali metals, such as sodium phenyl and sodium amide, may be used. The alkaline polymerization catalyst may be a quaternary ammonium base. In addition, as mentioned above, the catalyst may be an alkali metal hydride, such as sodium hydride. Certain alkali metal derivatives may be used, but many of them are undesirable. For example, alkali metal carbonates and alkaline earth metal hydroxides tend to be insoluble and therefore undesirable. Lithium hydroxide (monohydrate) is also insoluble in 2-pyrrolidone.

[0019] In some embodiments, non-ionic bases can also be used as catalysts. For example, the polymerization can be catalyzed by strong nitrogen and phosphorus-containing non-ionic bases. Effective catalysts or initiators can include non-ionic bases with a pKa of 30 or greater. Examples of useful non-ionic bases include polyaminophosphazenes, such as those having the structure: [ka] (In the formula, R 1 is (C1-C8) alkyl, where if alkyl is greater than C3 it may be branched or linear, R is Me or both R together are --(CH2)4--, and m, n, and y are independently 0 to 3. or preferably the specific phosphazene bases Px (x=1 to 7) as defined below.1 Groups include t-butyl, t-heptyl (--C(CH3)2C(CH2)3), and t-octyl (--C(CH3)2CH2C(CH2)3). Preferred R are methyl and --(CH2)4--. When a non-ionic base is used as the catalyst, the polymerization can be carried out at a temperature between about 25° C. and about 200° C., depending on the type of polyamide being polymerized. In general, the lower the monomer molecular weight, the lower the polymerization temperature.

[0020] The catalyst may be used in an amount of about 0.5 to about 50% or more by weight, preferably 5 to 30% by weight, and most preferably 8 to 20% by weight, based on the 2-pyrrolidone monomer.

[0021]

[0021] A preferred ratio of CO2 to alkaline polymerization catalyst has been found to be from about 2 to about 20 moles of catalyst per mole of CO2, or from about 4 to about 10 moles of catalyst per mole of CO2. The temperature at which the CO2 is added to the catalyst can be varied over a wide range, with results being obtained at temperatures ranging from 18°C ​​(near the freezing point of the solution of catalyst in monomer) to over 130°C, or between about 40°C and about 60°C.

[0022]

[0022] In some embodiments, the alkaline polymerization catalyst is an alkali metal salt of 2-pyrrolidone, such as sodium or potassium pyrrolidonate. When CO2 is bubbled into a reaction mixture of 2-pyrrolidone monomer and an alkali metal pyrrolidonate catalyst, an adduct of CO2 and the alkali metal pyrrolidonate is formed. It has been found that this adduct can be used for polymerization when the alkali metal pyrrolidonate is also present.

[0023]

[0023] CO2 can be bubbled into the mixture of 2-pyrrolidone monomer and alkali metal pyrrolidonate at a ratio of about one-quarter to about one mole of CO2 per mole of alkali metal pyrrolidonate, although more or less CO2 can be used. If a larger amount of CO2 is used, for example more than one-half mole of CO2 per mole of alkali metal pyrrolidonate, the additional CO2 may not be readily absorbed. If a smaller amount of CO2 is used, for example 2 moles of alkali metal pyrrolidonate per 0.5 moles of CO2, the reaction mixture will contain 2-pyrrolidone monomer, alkali metal pyrrolidonate, and CO2-alkali metal pyrrolidonate adduct. Generally, good results are obtained by stopping the addition of CO2 just before absolute saturation, but this is not essential. Best results are obtained by using somewhat less than 1 / 2 mole of CO2 per mole of alkali metal pyrrolidonate, for example, a ratio of 1 / 4 to 3 / 8 moles of CO2 per mole of pyrrolidonate. In either case, the reaction mixture is placed in a polymerization vessel and the monomers polymerized with or without further addition of CO2. If desired, the reaction between CO2 and the alkali metal pyrrolidonate can be carried out prior to contacting the bulk of the 2-pyrrolidone monomer.

[0024]

[0024] Although described herein as being carried out in the presence of CO2, the process can also be carried out without adding CO2 at all, where the remaining ingredients and conditions can remain the same. Even if no CO2 is added during the process, the polymerization will proceed as described, but on a much longer time scale and at a lower conversion.

[0025] In some embodiments, the polymerization of 2-pyrrolidone can be carried out in the following manner. First, the 2-pyrrolidone monomer is reacted with an alkali metal hydroxide, preferably NaOH or KOH, and the water formed during the reaction is removed by distillation to form in situ an anhydrous solution of the alkali metal salt of 2-pyrrolidone in the 2-pyrrolidone to be polymerized. The removal of water can be carried out under reduced pressure (e.g., pressure below atmospheric pressure of 14.7 psia) and at temperatures between 18°C ​​and 150°C, preferably between 25°C and 100°C, and most preferably between 25°C and 45°C. In the presence of water, adverse reactions can occur resulting in ring opening of the 2-pyrrolidone monomer and inhibiting the polymerization reaction. Instead of an alkali metal hydroxide, an alkali metal alcoholate, preferably NaOCH3 or KOCH3, can be used to form the alkali metal pyrrolidonate to form a solution of the alkali metal pyrrolidonate in 2-pyrrolidone. Any source of alkali metal can be used to form the pyrrolidonate, provided that no undesirable by-products are formed and the sensitive pyrrolidone ring is not destroyed. Undesirable by-products are those by-products that act as polymerization inhibitors. Sodium metal is an example of an alkali metal source that should not be used. After removing water from the reaction mixture, CO2 can be bubbled in to form an alkali metal pyrrolidnate-CO2 adduct in situ, thereby initiating polymerization. If desired, additional 2-pyrrolidone monomer can be added to the alkali metal pyrrolidonate solution prior to the introduction of CO2. Suitably, the 2-pyrrolidone monomer can be contacted with 0.01 to 10% by weight CO2 based on the weight of the 2-pyrrolidone monomer. For example, amounts of 0.2 to 6% by weight, or alternatively 0.5 to 3% by weight, based on the weight of the 2-pyrrolidone monomer can be used.

[0026] Alternatively, the polymerization of 2-pyrrolidione can be carried out by reaction of the monomer with potassium tert-butoxide. This base, or a similar base, can be used in a similar process as described above, where other conditions and ingredients can be the same or similar. However, in the example where potassium tert-butoxide is used, removal of tert-butanol occurs as opposed to water. Apart from this, the reaction proceeds as described above.

[0027]

[0027] The amount of carbon dioxide can also be expressed as a mole percent of the moles of alkaline polymerization catalyst. For example, the amount of carbon dioxide is about 0.06-60 mole percent based on the moles of alkaline polymerization catalyst, although larger amounts, such as up to about 80 mole percent CO2 based on the moles of alkaline polymerization catalyst, have been used. Typically, the amount of CO2 on a molar basis will be 10-80 mole percent based on the moles of alkaline polymerization catalyst.

[0028]

[0028] CO2 can be introduced into the system other than by bubbling CO2 into the mixture of 2-pyrrolidone and alkaline polymerization catalyst. For example, the CO2 source can be a compound that transfers CO2 to the mixture of 2-pyrrolidone monomer and alkaline polymerization catalyst, provided that the anion remaining after loss of CO2 from the compound is not detrimental to the polymerization. Adducts of carbon dioxide and alkali metal or quaternary ammonium pyrrolidonates can be added to the mixture of 2-pyrrolidone monomer and alkaline polymerization catalyst with or without adding CO2 gas to the system, as is possible with adducts of CO2 and alkali metal or quaternary ammonium caprolactamates. These adducts are added to the system on the same weight basis as CO2. A convenient method for preparing the adducts is to bubble CO2 into an anhydrous mixture of pyrrolidonates and 2-pyrrolidone under vacuum until a sudden increase in pressure occurs, indicating that CO2 is no longer readily absorbed. The adducts are precipitated by adding benzene or another organic precipitant to the solution. A free-flowing, non-hygroscopic white powder is recovered from the precipitate. Alternatively, an organic precipitant can be added to the anhydrous solution of pyrrolidonate in 2-pyrrolidone prior to bubbling CO2 through the solution, in which case a precipitate forms as CO2 is absorbed. Because CO2 must react with the anhydrous pyrrolidonate, it is preferred to form the CO2-pyrrolidonate adduct by adding CO2 to the anhydrous solution of pyrrolidonate in 2-pyrrolidone, where the pyrrolidonate is formed in situ as described herein.

[0029]

[0029] In a similar method, an adduct of CO2 and caprolactamate is formed by bubbling CO2 through an anhydrous solution of caprolactamate in caprolactam and adding an organic precipitant either before or after the addition of CO2. Generally, temperatures above 90°C are avoided when caprolactamate is formed in situ.

[0030]

[0030] In some embodiments, carbon dioxide can be used as the sole polymerization activator, but other polymerization activators can be used together with carbon dioxide. Other activators that can be used together with carbon dioxide are acyl compounds, such as organic acyl peroxides, carboxylic acid anhydrides, lactones, lactides, N-acyl derivatives of lactams, acyl halides, and alcohol esters of carboxylic acids.

[0031]

[0031] In addition, any of the following activators can be used: carbon disulfide, N-substituted secondary amides, cyanuric chloride, organic isocyanates, adipimide, N-iminopyrrolidone, N-monocarbonylpyrrolidone and organic acid amides, aromatic carbonyls and organic acid amides, chlorine, bromine, N-bromopyrrolidone, or N-chloropyrrolidone, NO2 or organic nitrites, P2O5 and other oxides or group V elements, N,N-disubstituted ureas, halides and oxyhalides of sulfur and phosphorus, oxides of group VI elements, halosilanes, phosphorus dichloride benzene, phosphorus oxychloride benzene, phosphorus trichloride, thionyl chloride, and / or tetramethylammonium chloride. These activators can be used in the polymerization reaction instead of CO2 or together with CO2. They can be added before or preferably after the addition of CO2. For example, in the case of tetramethylammonium chloride, a CO2 adduct is formed, and then tetramethylammonium chloride is added to the solution and mixed thoroughly to carry out the polymerization.

[0032]

[0032] Generally, the polymerization can be carried out in the substantial absence of water, but anhydrous conditions are not critical. For example, the amount of water can be less than about 1% by weight of the 2-pyrrolidone monomer, or less than about 0.1% by weight of the 2-pyrrolidone monomer. The 2-pyrrolidone used during the polymerization can be substantially pure. For example, the 2-pyrrolidone monomer is purified by fractional distillation under reduced pressure, or by recrystallization, or by a combination thereof.

[0033]

[0033] The resulting polymerized polypyrrolidone can have the formula previously described as Formula 1. Other polyamides can also be used in the modification herein, where the more general formula for polyamides is shown in Formula 2. For example, nylon 3 can be made using ring-opening polymerization beta-propiolactam with a base as described herein, or acrylamide can be polymerized to produce the polyamide. Similarly, nylon-2 can be synthesized using polymerization of glycine N-carboxyanhydride (NCA), and any other suitable method. Other polyamides can be produced using any suitable method.

[0034]

[0034] To improve the stability of the resulting polypyrrolidone, the structure of the polypyrrolidone can be modified to some extent to change the properties of the polymer. In some embodiments, the amide groups on the backbone structure of the polypyrrolidone can be modified between about 0.1% and about 10%, or between about 0.2% and about 8%, or between about 0.5% and about 5%. As used herein, percent modification refers to the number-average modification of amide units or groups on the polypyrrolidone backbone.

[0035] The resulting substituted polypyrrolidone has the formula: [ka] where n is as shown in formula 1, m is the same as in formula 1, and any of R1, R2, and R3 can include hydrogen or alkyl substituents. Other suitable substituents for substitution as R can include methoxy, methylol, methyl-methoxy, and the like. In some embodiments, this can result in R=MeOH, MeOMe, MeOEt, or MeOR. In various embodiments, R can be any alkyl group with appropriate substituents. In some embodiments, oxygen, sulfur contained in the repeat unit can be incorporated or used to modify the properties of the polymer. Although various methyl groups are shown, these groups can also include EtOH, EtOMe, which are included in the group defined by alkyl group herein. As used herein, the term "alkyl" can refer to both straight and branched chain alkyl groups, including alkylene. Exemplary alkyl groups include, for example, methyl, methylene (--CH2--), ethyl, isopropyl, n-butyl, t-butyl, hexyl, decyl, tetradecyl, 4-methylhexadecyl, eicosyl, and the like. The term alkyl includes lower alkyl groups, where "lower alkyl" means an alkyl group having 1 to 6 carbon atoms.

[0036] In some embodiments, the R group can be a reactive group. For example, the R group can be an epoxy, an isocyanate, or a similar reactive entity. The ability to modify the backbone with such groups can be achieved in the same manner as described herein, and the reactive groups can change the chemical properties of the resulting polymer.

[0037]

[0037] As shown in Formula 2, the modification can be associated with the amide groups in the polypyrrolidone, and the remaining groups, such as carboxyl groups, can be less modified, and in some embodiments, the carboxyl groups can have less than 0.1% modification in the final polypyrrolidone composition.

[0038] The polypyrrolidone modification process can be carried out by contacting poly-2-pyrrolidone (Formula 1) with a base to deprotonate the amide backbone, followed by an alkylating agent under reactive conditions. Alternatively or in addition, the polymer can be reacted with formaldehyde, with or without exposure to an alcohol or thiol, to modify the amide backbone. This process is typically carried out at a temperature in the range of about 18°C ​​to about 265°C for about 0.1 to about 120 hours. Typically, about 0.1 to 10 moles of modifier are used per mole of polypyrrolidone. The base polymer can be contacted as a finely divided powder to maximize contact between the polymer and the modification solution. Additionally, the base polymer can be dissolved in a suitable solvent for the reaction. Such suitable solvents are organic acids such as formic acid, fluorinated alcohols (hexafluoroisopropanol), polar protic solvents (DMF), polar aprotic solvents (DMSO, DMAc, NMP), or any solvent in which both the polymer and the reactants are soluble. The reaction rate is generally temperature dependent, and therefore shorter reaction times can be used with higher reaction temperatures, and vice versa. Thus, the degree of substitution can be controlled by adjusting the reaction time and temperature as well as the above reaction conditions.

[0039]

[0039] Suitable modifiers that can be used to modify the polypyrrolidone described in this specification include, but are not limited to, formaldehyde, paraformaldehyde, methyl iodide, methanol, ethanol, sodium hydride, and the like.

[0040] In some embodiments, the polypyrrolidone may be modified, for example, at one or more end caps in addition to the backbone modification. In these embodiments, the polypyrrolidone is reacted with certain alkanolamines or alkylene polyamines [e.g., NH2(CH2) nNH2]. Under very mild conditions, such as contact with water at room temperature, the end groups of polypyrrolidone can become unstable and open.

[0041]

[0041] Endcapping can cap one or more termini, such as any carboxyl end group. When direct capping of the end groups is used, the molecular weight of the product approaches (but is generally slightly less than) the weight average molecular weight of the starting polymer. The capping process of the present invention can be carried out by contacting the polypyrrolidone with an alkanolamine at a temperature in the range of about 20°C to 100°C, preferably about 25°C to 80°C, for about 0.5 to 50 hours, preferably about 1 to 30 hours, before or after any backbone modification.

[0042] The amount of capping agent can be selected to obtain the desired amount of end-capping. In some embodiments, between 1 and 2 moles of capping agent per mole of polymer can be used. At a 2:1 molar ratio between capping agent and polypyrrolidone, theoretically both ends of the polypyrrolidone are capped. However, in some embodiments, an excess of capping agent (e.g., a ratio of capping agent to polypyrrolidone of more than 2:1) can be used to ensure sufficient contact with the polymer. Thus, typically about 2 to 10 grams, preferably about 2 to 4 grams of capping agent can be used per gram of polymer. Alternatively, a suitable inert organic diluent or inert organic solvent for the capping agent can be advantageously used to reduce the amount of alkanolamine and / or alkylenediamine required to maximize polymer contact and facilitate handling.

[0043] Suitable alkanolamine capping agents that can be used include, but are not limited to, alkanolamines having 2-12 carbon atoms, preferably 2-6 carbon atoms, and at least one hydroxyl and one amino substituent, each substituted at different carbon atoms. The alkanolamine may be optionally substituted with a total of up to and including 5 hydroxyl and / or amino substituents substituted at different carbon atoms. It is important that the carbon atom contains only one substituent, because compounds having a carbon atom with two amino substituents, or two hydroxyl substituents, or one amino and one hydroxyl substituent, are unstable and are expected to degrade either during the initial process and / or in the polymer after melt spinning. Suitable alkanolamine species that can be used include, for example, ethanolamine, 3-aminopropanol, 10-aminodecanol; 4-amino-2-ethyl-butanol; 2-hydroxy-4-aminobutanol, 2,4-diaminobutanol, 2-hydroxymethyl-5-aminopentanol, and the like.

[0044] Suitable alkylene polyamines that can be used in the capping process include, for example, alkylene polyamines having 2 to 12 carbon atoms, preferably 2 to 6 carbon atoms, substituted with 2 to 5 amino substituents at different carbon atoms, and optionally 1 to 3 hydroxyl substituents at different carbon atoms, up to a total of 5 (including 5) such substituents. Suitable alkylene polyamine species include, for example, ethylene diamine, hexamethylene diamine, dodecylene diamine; 1,5-diamino-2-methylpentane; 1,2,4-triaminobutane; 1,5-diamino-3-hydroxyhexane; 1,2,6-triamino-4-3-hydroxyethylhexane, and the like. In terms of thermal stability of the capped polymer product for a particular molecular weight, generally the best results are obtained using alkanolamines, especially ethanolamines. When alkylene polyamines are used, it is preferred to use alkylene diamines such as ethylene diamine and hexamethylene diamine.

[0045] Additionally, various cyclic lactams, such as caprolactam, laurolactam, etc., can be used in the capping process.

[0046]

[0046] End capping can improve thermal stability, which can facilitate melt extrusion, particularly melt spinning, of the compositions of the present invention at temperatures within the range of 260°C to 285°C, or below about 280°C, or below 275°C.

[0047]

[0047] Modification of polypyrrolidone can result in the modified polymer having a lower melting temperature. In some embodiments, the melting temperature can be reduced by between about 0.1 and about 20°C, or between about 1 and about 10°C, compared to the base polypyrrolidone.

[0048] The resulting modified polyprrolidone can have a melting temperature of between about 220° C. and about 400° C., or between about 245° C. and about 260° C. In some embodiments, the modified polyprrolidone (e.g., based on backbone or end cap modifications) can have a decomposition temperature of at least about 200° C., or at least about 300° C., or between about 290° C. and about 330° C.

[0049]

[0049] The temperature difference between the melting temperature and the decomposition temperature can be increased, allowing a larger temperature range for forming useful articles. In some embodiments, this temperature difference can be between about 10°C and about 60°C, which can be greater than the difference between the melting temperature and the decomposition temperature of unmodified polypyrrolidone.

[0050]

[0050] Although described herein with respect to nylon 4, any suitable polyamide composition can be modified as shown herein. In particular, the same backbone and end-capping process can be used with other nylons, such as nylon 2, nylon 3, nylon 6, etc. In some aspects, the modifications shown herein can be used with proteins. In some aspects, proteins can be considered functionalized nylon 2, and these compounds can be both from natural sources and produced using new bioengineering techniques. The resulting protein chemistry can follow the polypyrrolidones described herein. In general, the decomposition temperatures of nylon 2, nylon 3, and proteins can be lower than the melting points of these polymers. Using the modification techniques shown herein can allow for a sufficient reduction in melting point and / or an increase in decomposition temperature to allow the polymer and protein to be more easily processed using any of the methods described herein. EXAMPLES

[0051] Working Example

[0051] Having generally described the present disclosure, the following examples are provided to illustrate the practice and advantages of specific embodiments of the present disclosure. It should be understood that these examples are provided for illustrative purposes and are not intended to limit the present specification or claims in any manner.

[0052] Example 1 Example 1: In this example, 0.5 g of polypyrrolidone was dissolved in 17 mL of formic acid at 60° C. 57 mg of paraformaldehyde was suspended in 680 mg of methanol at 60° C. An additional 680 mg of methanol was also incubated at 60° C. After the polypyrrolidone was completely dissolved in the formic acid, the paraformaldehyde solution was added rapidly. Thus, the formic acid solution containing polypyrrolidone, paraformaldehyde, and methanol was reacted at 60° C. for 5 minutes. After this time, the additional 680 mg of methanol was added rapidly to the solution and allowed to react for 30 minutes. After this reaction time, the solution was added dropwise into 350 mL of cold acetone. The precipitate was then removed and immersed in 150 mL of clean acetone for 10 minutes, removed, and dried at 50° C. The melting point of this sample was 259° C. and the decomposition temperature was 313° C. The melting point and decomposition temperatures of the starting polypyrrolidone were 267° C. and 288° C., respectively.

[0053] Example 2 Example 2: The same reaction conditions as in Example 1 were used, except that 100 mg of paraformaldehyde was suspended in 680 mg of methanol. In addition, the reaction time after addition of the paraformaldehyde suspension was 10 minutes. This sample exhibited a melting point temperature of 226°C and a decomposition temperature of over 304°C.

[0054] Example 3 Example 3: The reaction conditions were the same as above, except that 159 mg of paraformaldehyde was suspended in 680 mg of methanol. This sample exhibited a melting point temperature of 218° C. and a decomposition temperature of over 303° C.

[0055] Example 4 Example 4: 1.07 g of polypyrrolidone was added to a vial containing 1.6 g of formic acid, 1.07 g of paraformaldehyde, and 5.4 mL of methanol. The vial was shaken by hand, sealed, and placed in a 50° C. oven for 119 hours. The sample was then washed with excess 1:1 acetone:water, filtered, and then washed with excess acetone. The sample was allowed to dry. The sample showed a melting point temperature of 263° C. and a decomposition temperature of 306° C.

[0056] Example 5 Example 5: Polymerization of pyrrolidione to polypyrrolidone was carried out by mixing 11.2 g of pyrrolidone with 0.869 g of KOH at 110° C. under N2 until the KOH was completely dissolved. The sample was then further stirred for at least 10 minutes after complete dissolution. Dehydration was performed by short path distillation to remove approximately 10% by volume to ensure dryness. The reaction was then cooled to <60° C. under N2 atmosphere, followed by bubbling CO2 through the solution, which produced a cloudy yellow suspension. This was then placed in a scintillation vial and placed in a 50° C. oven for at least 8 hours. After reaction, the solid polypyrrolidone was removed from the vial, mechanically crushed to small pieces, washed with excess water, and dried. The melting point temperature was 263° C.

[0057] Example 6 Example 6: Polymerization conditions similar to Example 5, except that 1.422 g of tetramethylammonium chloride (previously dried) was added and stirred for 5 minutes after CO2 was added to the solution. The completed solution was then transferred to a vial and placed in a 50°C oven and allowed to react for at least 8 hours. Purification was carried out as in Example 5. The melting point temperature of this sample was 264°C and the decomposition temperature was 282°C.

[0058] Example 7 Example 7: The purified sample from Example 6 was dissolved in formic acid and precipitated in water. The sample was then filtered and washed with excess water to neutralize the solution. The polypyrrolidone was then dried. This sample has a melting point temperature of 266°C and a decomposition temperature of 299°C.

[0059] Example 8 Example 8: Polymerization of pyrrolidone was carried out similarly to Examples 5 and 6, except that 1.477 g of potassium tert-butoxide was used instead of KOH. After purification, the sample had a melting point temperature of 267° C. and a decomposition temperature of 285° C.

[0060] Example 9 Example 9: The polymer from Example 8 was dissolved in formic acid and purified as in Example 7. This sample had a melting point of 264°C, a decomposition temperature of 294°C.

[0061] Example 10 Example 10: 1 g of polypyrrolidone was mixed with 3 g of ethanolamine. The vial was kept at 150°C for 40 minutes. The vial was then cooled and the polymer was washed with excess water and dried. This sample has a melting point temperature of 268°C and a decomposition temperature of 304°C.

[0062] Example 11 Example 11: A sample of the melting point reduced polypyrrolidone (Example 2) was then reacted with ethanolamine to alter the endcapping (as in Example 10). This sample then exhibited a melting point temperature of 231°C, with a decomposition point of over 321°C.

[0063] Certain compositions and methods are described, specific aspects of which include, but are not limited to, the following:

[0064]

[0064] In a first aspect, the polyamide comprises a plurality of amide units forming a polymer chain and alkyl substituents on the amide groups, the polyamide having an amide unit substitution in an amount of between about 0.1% and about 10% amide units in the polymer chain.

[0065] A second aspect can include the polyamide of the first aspect, wherein the polymer chains include end caps, at least a portion of the end caps including alkyl substituents.

[0066] A third aspect can include the polyamide of the first or second aspect, wherein the alkyl substituents are methyl, ethyl, or butyl groups.

[0067]

[0067] A fourth aspect may include the polyamide of any one of the first to third aspects, wherein the polymer is biodegradable.

[0068] A fifth aspect can include the polyamide of any one of the first to fourth aspects, wherein the polymer is in the form of a sheet, film, filament, ribbon, shaped article, fabric, or fiber.

[0069]

[0069] A sixth embodiment can include the polyamide of any one of the first to fifth embodiments, wherein the polymer has a melting point between 220°C and about 400°C.

[0070]

[0070] A seventh embodiment can include the polyamide of any one of the first to sixth embodiments, wherein the polymer has a decomposition temperature of at least about 200°C.

[0071]

[0071] An eighth embodiment can include the polyamide of any one of the first to seventh embodiments, wherein the temperature difference between the melting temperature and the decomposition temperature of the polymer is at least about 20°C.

[0072]

[0072] A ninth aspect can include the polyamide of any one of the first to fifth aspects, in which the polyamide is nylon 2, nylon 3, nylon 4, nylon 6, or a protein.

[0073] In a tenth embodiment, the poly-2-pyrrolidone polymer has the formula: [ka] wherein m is 3 and R contains an alkyl substituent. wherein the poly-2-pyrrolidone has an amide group substitution in an amount of about 0.1% to about 10% amide groups in the poly-2-pyrrolidone.

[0074] An eleventh embodiment can include the polymer of the tenth embodiment, wherein R is a methyl group, an ethyl group, or a butyl group.

[0075]

[0075] A twelfth embodiment can include the polymer of the eleventh embodiment, wherein the polymer has a melting point between 220°C and about 400°C.

[0076]

[0076] A thirteenth embodiment can include the polymer of any one of the tenth through twelfth embodiments, wherein the polymer has a decomposition temperature of at least about 200°C.

[0077]

[0077] A fourteenth embodiment can include the polymer of any one of the tenth to thirteenth embodiments, wherein the temperature difference between the melting temperature and the decomposition temperature of the polymer is at least about 20°C.

[0078]

[0078] The fifteenth aspect may include the polymer of any one of the tenth to fourteenth aspects, wherein the polymer is biodegradable.

[0079]

[0079] A sixteenth aspect can include the polymer of any one of the tenth to fifteenth aspects, wherein the polymer is in the form of a sheet, film, filament, ribbon, shaped article, fabric, or fiber.

[0080]

[0080] In a seventeenth aspect, a method for forming a polyamide composition includes providing a polyamide, the polyamide including a plurality of amide groups in a main chain structure of the polyamide; and modifying a portion of the plurality of amide groups in the main chain structure with one or more alkyl substituents to form a polyamide composition, the polyamide having amide unit substitution in an amount of between about 0.1% and about 10% amide units in the main chain.

[0081]

[0081] An eighteenth aspect is a polyamide composition comprising: [ka] wherein R includes alkyl substituents on the amide groups of multiple amide groups. The method of the seventeenth aspect may include the method of the seventeenth aspect having the following formal:

[0082] In a nineteenth embodiment, the polyamide composition has the formula: [ka] wherein n is between 200 and 100,000, m is between 1 and 11, and any of R1, R2, and R3 may contain hydrogen or alkyl substituents. The method of the seventeenth aspect may include the method of the seventeenth aspect,

[0083]

[0082] A twentieth aspect can include the method of any one of the seventeenth to nineteenth aspects, wherein the carboxyl groups in the polyamide have less than 0.1% modification in the polyamide composition.

[0084]

[0083] A twenty-first aspect can include any one of the methods of the seventeenth through twentieth aspects, in which modifying a portion of the amide groups in the backbone structure with one or more alkyl substituents includes: contacting the polyamide with a modifier; deprotonating a portion of the amide groups; and alkylating the portion of the amide groups to form a polyamide composition.

[0085]

[0084] A twenty-second aspect may include the method of the twenty-first aspect, wherein modifying a portion of the multiple amide groups in the backbone structure with one or more alkyl substituents further includes dissolving the polyamide in a solvent before contacting the polyamide with the modifier.

[0086] A twenty-third aspect may include the method of the twenty-first or twenty-second aspects, wherein the modifier comprises a base, formaldehyde, paraformaldehyde, methyl iodide, methanol, ethanol, sodium hydride, or any combination thereof.

[0087]

[0086] A 24th aspect can include any one of the methods of the 17th to 25th aspects, in which modifying a portion of the multiple amide groups is carried out at a temperature in the range of 18°C ​​to about 265°C for a time period between about 0.1 to about 120 hours.

[0088]

[0087] A twenty-fifth aspect can include the method of any one of the seventeenth to twenty-fourth aspects, further including modifying a portion of the end caps of the polyamide composition.

[0089]

[0088] A twenty-sixth aspect may include the method of the twenty-fifth aspect, wherein modifying a portion of the end cap includes modifying the end cap using a capping agent, and the capping agent includes an alkanolamine, an alkylene polyamine, a cyclic lactam, or any combination thereof.

[0090] It should further be understood that the present description is not limited to the specific methods, compounds, materials, manufacturing techniques, uses, and applications described herein, as these may vary. It should also be understood that the terms used herein are used only for the purpose of describing certain embodiments, and are not intended to limit the scope of the present system and method. It should be noted that, when used in this specification and the appended claims (in this application or any application derived therefrom), the singular forms "a", "an", and "the" include plural references unless the context clearly indicates otherwise. Thus, for example, a reference to "an element" is a reference to one or more elements, including equivalents thereof known to those skilled in the art. Any conjunctions used should be understood in their most inclusive sense possible. Thus, the word "or" should be understood as having the definition of logical "or" rather than logical "exclusive or" unless the context clearly requires otherwise. Structures described herein should also be understood to mean functional equivalents of such structures. Language that can be interpreted to express approximation should be so understood unless the context clearly indicates otherwise.

[0091]

[0090] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this description belongs. Although preferred methods, techniques, devices, and materials are described, any methods, techniques, devices, or materials similar or equivalent to those described herein can be used to practice or test the present system and method. It should be understood that structures described herein can also refer to functional equivalents of such structures. The present system and method are described in detail with reference to their embodiments as shown in the accompanying drawings.

[0092]

[0091] Further variations and modifications will be apparent to persons skilled in the art upon reading the present disclosure. Such variations and modifications may include equivalent and other features which are already known in the art and which may be used instead of or in addition to features already described herein.

[0093]

[0092] Although claims may be constructed to particular combinations of features in this application or in any further application derived therefrom, it should be understood that the scope of the disclosure includes any novel feature or any novel combination of features disclosed herein, either explicitly or implicitly, or in any generalization thereof, whether or not relating to the same system or method claimed herein in any claim, and whether or not alleviating any or all of the same technical problems as the present systems and methods.

[0094]

[0093] Features that are described in the context of separate embodiments may also be provided in combination in a single embodiment. Conversely, various features that are described for brevity in the context of a single embodiment may also be provided separately or in any suitable subcombination. The applicant hereby notifies that new claims may be formulated to such features and / or combinations of such features during prosecution of this application or any further application derived therefrom.

Claims

1. a plurality of amide units forming a polymer chain; Alkyl substituents on the amide group wherein the polyamide has a substitution of said amide units in an amount of between about 0.1% and about 10% of said amide units in said polymer chain.

2. 2. The polyamide of claim 1 , wherein the polymer chains comprise end caps, at least a portion of the end caps comprising an alkyl substituent.

3. 2. The polyamide of claim 1, wherein the alkyl substituent is a methyl, ethyl, or butyl group.

4. The polyamide of claim 1 , wherein the polymer is biodegradable.

5. 10. The polyamide of claim 1 , wherein the polymer is in the form of a sheet, film, filament, ribbon, shaped article, fabric, or fiber.

6. Polyamide according to any one of claims 1 to 5, wherein the polymer has a melting point between 220°C and about 400°C.

7. 2. The polyamide of claim 1, wherein the polymer has a decomposition temperature of at least about 200°C.

8. 2. The polyamide of claim 1, wherein the polymer has a temperature differential of at least about 20° C. between its melting temperature and its decomposition temperature.

9. 2. The polyamide of claim 1, wherein the polyamide is nylon 2, nylon 3, nylon 4, nylon 6, or a protein.

10. The following formula: 【Chemistry 1】 where R includes an alkyl substituent on the amide group. wherein said poly-2-pyrrolidone has a substitution of said amide groups in an amount of from about 0.1% to about 10% of said amide groups in said poly-2-pyrrolidone.

11. 11. The polymer of claim 10, wherein R is a methyl group, an ethyl group, or a butyl group.

12. The polymer of claim 10, wherein the polymer has a melting point between 220°C and about 400°C.

13. 11. The polymer of claim 10, wherein the polymer has a decomposition temperature of at least about 200°C.

14. 11. The polymer of claim 10, wherein the polymer has a temperature differential of at least about 20°C between its melting temperature and its decomposition temperature.

15. The polymer of claim 10 , wherein the polymer is biodegradable.

16. 11. The polymer of claim 10, wherein the polymer is in the form of a sheet, film, filament, ribbon, shaped article, fabric, or fiber.

17. 1. A method of forming a polyamide composition comprising: providing a polyamide, the polyamide comprising a plurality of amide groups in a backbone structure of the polyamide; and modifying a portion of said plurality of amide groups in said backbone structure with one or more alkyl substituents to form said polyamide composition, wherein said polyamide has a substitution of said amide units in an amount of between about 0.1% and about 10% amide units in said backbone.

18. The polyamide composition comprising: 【Chemistry 2】 wherein R includes alkyl substituents on the amide groups of said plurality of amide groups.

20. The method of claim 17 having the formal

19. The polyamide composition is a polyamide having the following formula: 【Chemistry 3】 wherein n is between 200 and 100,000, m is between 1 and 11, and R １ , R ２ , and R ３ Each of the groups may contain hydrogen or alkyl substituents.

20. The method of claim 17, comprising:

20. 20. The method of claim 17, wherein the carboxyl groups in the polyamide have less than 0.1% modification in the polyamide composition.

21. modifying said portion of said amide groups in said backbone structure with one or more alkyl substituents; contacting the polyamide with a modifier; deprotonating said portion of said plurality of amide groups; alkylating the portion of the plurality of amide groups to form the polyamide composition; 20. The method of claim 17, comprising:

22. modifying said portion of said amide groups in said backbone structure with one or more alkyl substituents; 22. The method of claim 21 further comprising dissolving the polyamide in a solvent prior to contacting the polyamide with the modifier.

23. 22. The method of claim 21, wherein the modifying agent comprises a base, formaldehyde, paraformaldehyde, methyl iodide, methanol, ethanol, sodium hydride, or any combination thereof.

24. 18. The method of claim 17, wherein modifying the portion of the amide groups is carried out at a temperature in the range of 18° C. to about 265° C. for a time between about 0.1 to about 120 hours.

25. 20. The method of claim 17, further comprising modifying a portion of the end caps of the polyamide composition.

26. 26. The method of claim 25, wherein modifying the portion of the end cap comprises modifying the end cap with a capping agent, the capping agent comprising an alkanolamine, an alkylene polyamine, a cyclic lactam, or any combination thereof.

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