Dissolution or dispersion of poorly soluble polymer

Abstract

The present invention provides a method for producing a solution or dispersion that contains a poorly soluble polymer. The method includes mixing the poorly soluble polymer, a nonionic superbase, and an aprotic solvent in an inert gas atmosphere or an air atmosphere, wherein the poorly soluble polymer has a pKa of 50 or less under measurement conditions in which the temperature is 25°C and the solvent is acetonitrile, and the nonionic superbase has a molecular weight of 150 to 4,000 and has a branched structure and / or a cyclic structure.

Description

Dissolution or dispersion of poorly soluble polymers

[0001] This invention relates to the dissolution or dispersion of poorly soluble polymers. More specifically, this invention relates to a method for producing a solution or dispersion of a poorly soluble polymer, a solution or dispersion of a poorly soluble polymer, a method for producing cellulose nanofibers, a method for dissolving the surface of a poorly soluble polymer, and a method for adhering poorly soluble polymers to each other, utilizing the dissolution or dispersion of poorly soluble polymers.

[0002] Poorly soluble polymers are known to be difficult to process or handle because they are poorly soluble in solvents. Various techniques are known to facilitate this processing or handling by dissolving poorly soluble polymers in solvents. For example, Patent Document 1 discloses a technique for dissolving cellulose in dimethyl sulfoxide in the form of a cellulose carbonate anion by mixing cellulose, a type of poorly soluble polymer, dimethyl sulfoxide, and a base (e.g., 2-(tert-butyl)-1,1,3,3-tetramethylguanidine (BTMG)) under a carbon dioxide atmosphere. For details, paragraph

[0035] of Patent Document 1 describes the following reaction equation.

[0003]

[0004] Patent Document 2, like Patent Document 1, discloses a method that includes dissolving cellulose in an organic solvent by mixing cellulose, an organic solvent, and a base under a carbon dioxide atmosphere. In the method of Patent Document 2, since the dissolution of cellulose is performed under a carbon dioxide atmosphere, it is thought that the cellulose is dissolved in the organic solvent in the form of cellulose carbonate anions.

[0005] Patent Document 3 discloses a solvent containing tetraalkylammonium hydroxide, water, and dimethyl sulfoxide as a solvent used to dissolve aromatic polyamides, which are a type of poorly soluble polymer.

[0006] International Publication No. 2018 / 203835, Chinese Patent Application Publication No. 115926007, Specification International Publication No. 2024 / 116374

[0007] The methods described in Patent Documents 1 and 2 are limited to dissolving cellulose. Furthermore, the methods in Patent Documents 1 and 2 require the use of carbon dioxide, which is an environmentally harmful substance. Moreover, in the methods in Patent Documents 1 and 2, cellulose is dissolved in the form of cellulose carbonate anions, which have poor nucleophilicity. Therefore, the reaction requires high temperatures and long durations, potentially consuming a large amount of energy.

[0008] The method described in Patent Document 3 is limited to the dissolution of aromatic polyamides. Furthermore, in methods that use highly nucleophilic hydroxides, such as the method in Patent Document 3, the hydroxide may adversely affect the reaction of the poorly soluble polymer after dissolution (for example, the hydroxide used for dissolution may nucleophilically attack the poorly soluble polymer).

[0009] This invention was made in view of the circumstances described above, and its purpose is to provide a method for dissolving or dispersing various poorly soluble polymers without using carbon dioxide, which is an environmentally harmful substance.

[0010] As a result of diligent research by the present inventors, it has been discovered that a sparingly soluble polymer having a pKa of 50 or less under measurement conditions of 25°C and acetonitrile as the solvent can be dissolved or dispersed in an aprotic solvent by mixing it with a bulky nonionic superbase and an aprotic solvent under an inert gas atmosphere or an atmospheric atmosphere. Based on this finding, the present invention is as follows.

[0011] [1] A method for producing a solution or dispersion containing a sparingly soluble polymer, the method comprising mixing the sparingly soluble polymer, a nonionic superbase, and an aprotic solvent under an inert gas atmosphere or an atmospheric atmosphere, wherein the pKa of the sparingly soluble polymer is 50 or less under measurement conditions of a temperature of 25°C and the solvent is acetonitrile, the molecular weight of the nonionic superbase is 150 to 4,000, and the nonionic superbase has a branched structure and / or a cyclic structure.

[0012] [2] The method according to [1], wherein the amount of the nonionic superbase is 0.01 to 500 mol%, preferably 0.1 to 200 mol%, and more preferably 0.1 to 100 mol%, relative to the active hydrogen atoms of the sparingly soluble polymer.

[0013] [3] The nonionic superbase is a superbase represented by formula (1) below to a superbase represented by formula (12) below:

[0014]

[0015]

[0016]

[0017]

[0018]

[0019] The method according to [1] or [2], which is at least one selected from the group consisting of (wherein Me represents a methyl group, Et represents an ethyl group, and tBu represents a tert-butyl group).

[0020] [4] The method according to [1] or [2], wherein the nonionic superbase is at least one selected from the group consisting of the superbase represented by formula (2), the superbase represented by formula (4), the superbase represented by formula (6), the superbase represented by formula (11), and the superbase represented by formula (12), and preferably the superbase represented by formula (6). [5] The method according to [1] or [2], wherein the nonionic superbase is a superbase having a phosphazene structure, preferably at least one selected from the group consisting of the superbase represented by formula (1) to the superbase represented by formula (10), more preferably at least one selected from the group consisting of the superbase represented by formula (2), the superbase represented by formula (4), and the superbase represented by formula (6), and even more preferably the superbase represented by formula (6).

[0021] [6] The method according to any one of [1] to [5] above, wherein the poorly soluble polymer is at least one selected from the group consisting of cellulose, starch, chitin, aromatic polyamide, protein, and polyfluorene, preferably cellulose.

[0022] [7] The method according to any one of [1] to [6], wherein the aprotic solvent comprises at least one aprotic polar solvent selected from the group consisting of dimethyl sulfoxide, pyridine, 2-methylpyridine, 1-methylimidazole, and N,N-dimethylacetamide, preferably at least one aprotic polar solvent selected from the group. [8] The method according to [7], wherein the group consists of dimethyl sulfoxide and pyridine.

[0023] [9] A solution or dispersion containing a sparingly soluble polymer (excluding cellulose in the form of cellulose carbonate anion), wherein the solution or dispersion comprises the sparingly soluble polymer, a nonionic superbase, and an aprotic solvent, wherein the pKa of the sparingly soluble polymer is 50 or less under measurement conditions of a temperature of 25°C and the solvent is acetonitrile, the molecular weight of the nonionic superbase is 150 to 4,000, and the nonionic superbase has a branched structure and / or a cyclic structure.

[0024]

[10] The solution or dispersion according to [9], wherein the amount of the nonionic superbase is 0.01 to 500 mol%, preferably 0.1 to 200 mol%, and more preferably 0.1 to 100 mol%, relative to the active hydrogen atoms of the sparingly soluble polymer.

[0025]

[11] The solution or dispersion according to [9] or

[10] , wherein the nonionic superbase is at least one selected from the group consisting of the superbase represented by formula (1) to the superbase represented by formula (12).

[12] The solution or dispersion according to [9] or

[10] , wherein the nonionic superbase is at least one selected from the group consisting of the superbase represented by formula (2), the superbase represented by formula (4), the superbase represented by formula (6), the superbase represented by formula (11), and the superbase represented by formula (12), preferably the superbase represented by formula (6).

[13] The solution or dispersion according to [9] or

[10] , wherein the nonionic superbase is a superbase having a phosphazene structure, preferably at least one selected from the group consisting of the superbase represented by formula (1) to the superbase represented by formula (10), more preferably at least one selected from the group consisting of the superbase represented by formula (2), the superbase represented by formula (4), and the superbase represented by formula (6), and even more preferably the superbase represented by formula (6).

[0026]

[14] The solution or dispersion according to any one of [9] to

[13] , wherein the poorly soluble polymer is at least one selected from the group consisting of cellulose, starch, chitin, aromatic polyamide, protein, and polyfluorene, preferably cellulose.

[0027]

[15] The solution or dispersion according to any one of [9] to

[14] , wherein the aprotic solvent comprises at least one aprotic polar solvent selected from the group consisting of dimethyl sulfoxide, pyridine, 2-methylpyridine, 1-methylimidazole, and N,N-dimethylacetamide, preferably at least one aprotic polar solvent selected from the group.

[16] The solution or dispersion according to any one of [9] to

[14] , wherein the group consists of dimethyl sulfoxide and pyridine.

[0028]

[17] A method for producing cellulose nanofibers, the method comprising mixing cellulose, a nonionic superbase, and an aprotic solvent under an inert gas atmosphere or an air atmosphere to obtain a solution or dispersion (preferably a solution) of cellulose, and mixing the solution or dispersion (preferably a solution) with water to obtain the cellulose nanofibers, the molecular weight of the nonionic superbase being 150 to 4,000, and the nonionic superbase having a branched structure and / or a cyclic structure.

[0029]

[18] The method according to

[17] , wherein the amount of the nonionic superbase is 0.01 to 500 mol%, preferably 0.1 to 200 mol%, more preferably 0.1 to 100 mol% based on the active hydrogen atoms of the poorly soluble polymer.

[0030]

[19] The method according to

[17] or

[18] , wherein the nonionic superbase is at least one selected from the group consisting of the superbase represented by the formula (1) to the superbase represented by the formula (12).

[20] The method according to

[17] or

[18] , wherein the nonionic superbase is at least one selected from the group consisting of the superbase represented by the formula (2), the superbase represented by the formula (4), the superbase represented by the formula (6), the superbase represented by the formula (11), and the superbase represented by the formula (12), preferably the superbase represented by the formula (6).

[21] The method according to

[17] or

[18] , wherein the nonionic superbase is a superbase having a phosphazene structure, preferably at least one selected from the group consisting of the superbase represented by the formula (1) to the superbase represented by the formula (10), more preferably at least one selected from the group consisting of the superbase represented by the formula (2), the superbase represented by the formula (4), and the superbase represented by the formula (6), and still more preferably the superbase represented by the formula (6).

[0031]

[22] The method according to any one of

[17] to

[21] above, wherein the aprotic solvent contains at least one aprotic polar solvent selected from the group consisting of dimethyl sulfoxide, pyridine, 2-methylpyridine, 1-methylimidazole, and N,N-dimethylacetamide, and preferably is at least one aprotic polar solvent selected from the group.

[23] The method according to

[22] above, wherein at least one aprotic polar solvent selected from the group is dimethyl sulfoxide.

[0032]

[24] A method for dissolving the surface of a poorly soluble polymer, the method comprising contacting the surface of the poorly soluble polymer with a solution containing a nonionic superbase and an aprotic solvent to dissolve the surface of the poorly soluble polymer, wherein the pKa of the poorly soluble polymer is 50 or less under the measurement conditions of a temperature of 25 °C and a solvent of acetonitrile, the molecular weight of the nonionic superbase is 150 to 4,000, and the nonionic superbase has a branched structure and / or a cyclic structure.

[0033]

[25] The method according to

[24] above, wherein the amount of the nonionic superbase is 0.01 to 500 mol%, preferably 0.1 to 200 mol%, more preferably 0.1 to 100 mol% based on the active hydrogen atoms of the poorly soluble polymer.

[0034]

[26] The method according to

[24] or

[25] , wherein the nonionic superbase is at least one selected from the group consisting of the superbase represented by formula (1) to the superbase represented by formula (12).

[27] The method according to

[24] or

[25] , wherein the nonionic superbase is at least one selected from the group consisting of the superbase represented by formula (2), the superbase represented by formula (4), the superbase represented by formula (6), the superbase represented by formula (11), and the superbase represented by formula (12), preferably the superbase represented by formula (6).

[28] The method according to

[24] or

[25] , wherein the nonionic superbase is a superbase having a phosphazene structure, preferably at least one selected from the group consisting of the superbase represented by formula (1) to the superbase represented by formula (10), more preferably at least one selected from the group consisting of the superbase represented by formula (2), the superbase represented by formula (4), and the superbase represented by formula (6), and even more preferably the superbase represented by formula (6).

[0035]

[29] The method according to any one of

[24] to

[28] , wherein the poorly soluble polymer is at least one selected from the group consisting of cellulose, starch, chitin, aromatic polyamide, protein, and polyfluorene, preferably an aromatic polyamide.

[0036]

[30] The method according to any one of

[24] to

[29] , wherein the aprotic solvent comprises at least one aprotic polar solvent selected from the group consisting of dimethyl sulfoxide, pyridine, 2-methylpyridine, 1-methylimidazole, and N,N-dimethylacetamide, preferably at least one aprotic polar solvent selected from the group.

[31] The method according to

[30] , wherein the at least one aprotic polar solvent selected from the group is dimethyl sulfoxide.

[0037]

[32] A method for bonding two sparingly soluble polymers to each other, the method comprising: contacting one surface of the sparingly soluble polymer with a solution containing a nonionic superbase and an aprotic solvent; and contacting the one surface of the sparingly soluble polymer that has been in contact with the solution with the other surface of the sparingly soluble polymer, wherein the pKa of the sparingly soluble polymer is 50 or less under measurement conditions of a temperature of 25°C and the solvent is acetonitrile; the molecular weight of the nonionic superbase is 150 to 4,000; and the nonionic superbase has a branched structure and / or a cyclic structure.

[0038]

[33] The method according to

[32] , wherein the amount of the nonionic superbase is 0.01 to 500 mol%, preferably 0.1 to 200 mol%, and more preferably 0.1 to 100 mol%, relative to the active hydrogen atoms of the sparingly soluble polymer.

[0039]

[34] The method according to

[32] or

[33] , wherein the nonionic superbase is at least one selected from the group consisting of the superbase represented by formula (1) to the superbase represented by formula (12).

[35] The method according to

[32] or

[33] , wherein the nonionic superbase is at least one selected from the group consisting of the superbase represented by formula (2), the superbase represented by formula (4), the superbase represented by formula (6), the superbase represented by formula (11), and the superbase represented by formula (12), preferably the superbase represented by formula (6).

[36] The method according to

[32] or

[33] , wherein the nonionic superbase is a superbase having a phosphazene structure, preferably at least one selected from the group consisting of the superbases represented by formula (1) to the superbases represented by formula (10), more preferably at least one selected from the group consisting of the superbase represented by formula (2), the superbase represented by formula (4), and the superbase represented by formula (6), and even more preferably the superbase represented by formula (6).

[0040]

[37] The method according to any one of

[32] to

[36] , wherein the poorly soluble polymer is at least one selected from the group consisting of cellulose, starch, chitin, aromatic polyamide, protein, and polyfluorene, preferably an aromatic polyamide.

[0041]

[38] The method according to any one of

[32] to

[37] , wherein the aprotic solvent comprises at least one aprotic polar solvent selected from the group consisting of dimethyl sulfoxide, pyridine, 2-methylpyridine, 1-methylimidazole, and N,N-dimethylacetamide, preferably at least one aprotic polar solvent selected from the group.

[39] The method according to

[38] , wherein the at least one aprotic polar solvent selected from the group is dimethyl sulfoxide.

[0042] According to the present invention, various poorly soluble polymers can be dissolved or dispersed without using carbon dioxide, which is an environmentally harmful substance.

[0043] This graph shows the results of dynamic light scattering at 25°C for the cellulose dispersion and cellulose solution obtained in Example 12. This is an atomic force microscope image taken in Example 13. This is an atomic force microscope image taken in Example 37.

[0044] The present invention will be described in order below. Note that the descriptions herein can be combined with each other unless it is clearly stated that they cannot be combined.

[0045] <Method for Producing a Solution or Dispersion of a Sparingly Soluble Polymer> The present invention provides a method for producing a solution or dispersion containing a sparingly soluble polymer, the method comprising mixing the sparingly soluble polymer, a nonionic superbase, and an aprotic solvent under an inert gas atmosphere or an atmospheric atmosphere, wherein the pKa of the sparingly soluble polymer is 50 or less under measurement conditions where the temperature is 25°C and the solvent is acetonitrile, the molecular weight of the nonionic superbase is 150 to 4,000, and the nonionic superbase has a branched structure and / or a cyclic structure.

[0046] In this specification, "polymer" means a compound having two or more repeating units. The number of repeating units in the polymer is preferably three or more, more preferably ten or more, preferably 10,000 or less, and more preferably 1,000 or less.

[0047] In this specification, "poorly soluble polymer" means a polymer whose solubility (i.e., the maximum amount that can be dissolved in 100 g of solvent (DMSO)) is 0.1 g or less under measurement conditions where the temperature is 25°C and the solvent is dimethyl sulfoxide (hereinafter sometimes abbreviated as "DMSO"). The solubility under the above conditions may hereinafter be referred to as "solubility (25°C and DMSO)".

[0048] In this specification, "solution or dispersion containing a sparingly soluble polymer" means a solution or dispersion containing a sparingly soluble polymer. In this specification, "solution containing a sparingly soluble polymer" means a liquid in which the sparingly soluble polymer is dissolved in a solvent and is transparent to the naked eye. In this specification, "dispersion containing a sparingly soluble polymer" means a mixture of a sparingly soluble polymer as the dispersed phase and a liquid as the dispersion medium, in which, when left standing at 25°C, the sparingly soluble polymer remains suspended in the dispersion medium for 5 minutes or more without settling. In this specification, "solution or dispersion containing a sparingly soluble polymer," "solution containing a sparingly soluble polymer," and "dispersion containing a sparingly soluble polymer" may be abbreviated as "solution or dispersion," "solution," and "dispersion," respectively.

[0049] The pKa of the sparingly soluble polymer used in the present invention is 50 or less under measurement conditions of a temperature of 25°C and acetonitrile as the solvent. By mixing such a sparingly soluble polymer with a pKa, a bulky nonionic superbase (i.e., a nonionic superbase with a molecular weight of 150 to 4,000 and having a branched and / or cyclic structure), and an aprotic solvent, a salt is formed between the sparingly soluble polymer and the bulky nonionic superbase in the aprotic solvent. It is presumed that hydrogen bonding, stacking, etc., of the sparingly soluble polymer are inhibited by the bulky nonionic superbase, and as a result, the sparingly soluble polymer in the form of a salt dissolves or disperses. However, the present invention is not limited to this presumed mechanism.

[0050] From the standpoint of practical applicability and high industrial and academic demand, the poorly soluble polymer is preferably at least one selected from the group consisting of cellulose, starch, chitin, aromatic polyamide, protein, and polyfluorene, and more preferably cellulose. The aforementioned cellulose, starch, chitin, aromatic polyamide, protein, and polyfluorene are all poorly soluble polymers, and their solubility (at 25°C and DMSO) is 0.1 g or less. In other words, the poorly soluble polymers cellulose, starch, chitin, aromatic polyamide, protein, and polyfluorene are, respectively, poorly soluble cellulose, poorly soluble starch, poorly soluble chitin, poorly soluble aromatic polyamide, poorly soluble protein, and poorly soluble polyfluorene.

[0051] The poorly soluble polymers, cellulose, starch, chitin, aromatic polyamides, proteins, and polyfluorenes, may be used individually or in mixtures containing them. Examples of mixtures containing the poorly soluble polymers include cotton containing cellulose, sawdust containing cellulose, rice bran containing cellulose, bagasse (sugarcane residue) containing cellulose, and wool containing protein.

[0052] In this specification, “superbase” means a pK value at a temperature of 25°C and with acetonitrile as the solvent. ｂＨ＋means a base with a pK of 19 or more. Note that the pK under the above conditions ｂＨ＋ will be hereinafter described as "pK ｂＨ＋ (25 °C and acetonitrile)".

[0053] In this specification, the "pK ｂＨ＋ (25 °C and acetonitrile)" of a superbase refers to the following equilibrium reaction under the conditions that the temperature is 25 °C and the solvent is acetonitrile: X−H + DBU ⇔ X + DBU−H (wherein X represents the target superbase, X−H represents the protonated form of the target superbase, DBU represents 1,8-diazabicyclo[5.4.0]-7-undecene, and DBU−H represents the protonated form of DBU).) and the pK ｂＨ＋ value (hereinafter described as "pK ｂＨ＋ (DBU)", pK ｂＨ＋ (DBU) = 24.3), the following formula: pK ｂＨ＋ (25 °C and acetonitrile) = pK ｂＨ＋ (DBU) − log １０ ([X][DBU−H] / [X−H][DBU]) = 24.3 − log １０ ([X][DBU−H] / [X−H][DBU]) (wherein [X] represents the concentration (M) of X, [DBU−H] represents the concentration (M) of DBU−H, [X−H] represents the concentration (M) of X−H, and [DBU] represents the concentration (M) of DBU).) It is a value calculated from. Note that pK ｂＨ＋ (DBU) = 24.3 used in the above formula is known and is described in, for example, Liebigs Annalen, 1996, 1055-1081. Further, in the above calculation formula, the activity of each component is approximated by the concentration of each component. The higher the pK ｂＨ＋ (25 °C and acetonitrile) of a base, the higher its basicity.

[0054] In this specification, the "nonionic superbase" means a superbase that is not a salt. In this specification, the "salt" means a compound composed of an anion and a cation (for example, tetraalkylammonium hydroxide).

[0055] Furthermore, the bulky nonionic superbases used in this invention (i.e., nonionic superbases with a molecular weight of 150 to 4,000 and having a branched and / or cyclic structure) have low nucleophilicity due to their bulkiness. Therefore, the present invention, which uses bulky nonionic superbases, is less likely to adversely affect the reaction of poorly soluble polymers after dissolution compared to methods using highly nucleophilic hydroxides such as those described in Patent Document 3.

[0056] From the viewpoint of availability, the molecular weight of the nonionic superbase is preferably 150 to 2000, more preferably 180 to 1200.

[0057] In one embodiment of the present invention, from the viewpoint of availability, the nonionic superbase is preferably at least one selected from the group consisting of the superbase represented by the following formula (1) to the superbase represented by the following formula (12) (wherein Me represents a methyl group, Et represents an ethyl group, and tBu represents a tert-butyl group). In this specification, "the superbase represented by formula (1)" etc. may be abbreviated as "superbase (1)", etc.

[0058]

[0059]

[0060]

[0061]

[0062]

[0063] In one embodiment of the present invention, the nonionic superbase is more preferably at least one selected from the group consisting of superbase (2), superbase (4), superbase (6), superbase (11), and superbase (12), and even more preferably superbase (6).

[0064] In one embodiment of the present invention, the nonionic superbase is preferably a superbase having a phosphazene structure, more preferably at least one selected from the group consisting of superbase (1) to superbase (10), even more preferably at least one selected from the group consisting of superbase (2), superbase (4), and superbase (6), and particularly preferably superbase (6). Here, "phosphazene structure" means a structure in which phosphorus atoms and nitrogen atoms are alternately bonded.

[0065] Nonionic superbases can be commercially available. Superbase (1) can be obtained, for example, from Sigma-Aldrich as "tert-butylimino-tris(dimethylamino)phosphorane". Superbase (2) can be obtained, for example, from Sigma-Aldrich as "tert-butylimino-tri(pyrrolidino)phosphorane". Superbase (3) can be obtained, for example, from Sigma-Aldrich as "2-tert-butyl-2-diethylamino-1,3-dimethylperhydro-1,3,2-diazaphosphorine". Superbase (4) can be obtained, for example, from Sigma-Aldrich as "1-tert-butyl-2,2,4,4,4-pentakis(dimethylamino)-2λ". ５ ,4λ ５ - It can be obtained as "Catenagy (phosphazene)". The superbase (5) can be obtained, for example, from Sigma-Aldrich as "1-ethyl-2,2,4,4,4-pentakis(dimethylamino)-2λ". ５ ,4λ ５ -Catenagy (phosphazene) can be obtained. The superbase (6) can be obtained, for example, from Sigma-Aldrich as "1-tert-butyl-4,4,4-tris(dimethylamino)-2,2-bis[tris(dimethylamino)phosphoranylideneamino]-2λ ５ ,4λ ５- It can be obtained as "Catenagy (phosphazene)". The superbase (11) can be obtained, for example, from Tokyo Chemical Industries as "1,3-di-tert-butylimidazole-2-ylidene". The superbase (12) can be obtained, for example, from Sigma-Aldrich as "2,8,9-triisopropyl-2,5,8,9-tetraaza-1-phosphabicyclo[3.3.3]undecane".

[0066] Nonionic superbases may be prepared by known methods. For example, superbase (7) can be prepared by the method described in Angewandte Chemie International Edition, 2019, 58, 14633-14638. Superbase (8) can be prepared by the method described in Angewandte Chemie International Edition, 2019, 58, 10335-10339. Superbase (9) can be prepared by the method described in Liebigs Annalen, 1996, 1055-1081. Superbase (10) can be prepared by the method described in Angewandte Chemie International Edition, 2017, 56, 12987-12990.

[0067] The present invention relates to a method for producing a solution or dispersion, comprising mixing the sparingly soluble polymer, a nonionic superbase, and an aprotic solvent under an inert gas atmosphere or an atmospheric atmosphere. In this specification, "inert gas" means a gas that does not react with the sparingly soluble polymer. For example, carbon dioxide, which reacts with cellulose, a type of sparingly soluble polymer, is not included in "inert gas" in this specification. Examples of inert gases include nitrogen gas and argon gas. Only one inert gas may be used, or two or more may be used in combination. "Under an inert gas atmosphere or atmospheric atmosphere" is preferably an inert gas atmosphere from the viewpoint of unreactivity, and more preferably a nitrogen gas atmosphere from the viewpoint of economic efficiency.

[0068] From the viewpoint of solubility and economic efficiency, the aprotic solvent preferably comprises at least one aprotic polar solvent (hereinafter sometimes abbreviated as "aprotic polar solvent (I)") selected from the group consisting of dimethyl sulfoxide, pyridine, 2-methylpyridine, 1-methylimidazole, and N,N-dimethylacetamide (hereinafter sometimes abbreviated as "DMA"), and more preferably aprotic polar solvent (I). The group preferably consists of dimethyl sulfoxide and pyridine.

[0069] The aprotic solvent may include other aprotic solvents (hereinafter referred to as "other aprotic solvents"), as long as they do not inhibit the dissolution or dispersion of the poorly soluble polymer. Examples of other aprotic solvents include hexane, toluene, and tetrahydrofuran.

[0070] When using other aprotic solvents, the volume ratio of aprotic polar solvent (I) to the other aprotic solvent is preferably 40 / 60 to 99 / 1, more preferably 50 / 50 to 99 / 1, from the viewpoint of solubility and economy. When hexane is used as the other aprotic solvent, the volume ratio of aprotic polar solvent (I) to hexane is preferably 60 / 40 to 99 / 1, more preferably 70 / 30 to 99 / 1. When toluene is used as the other aprotic solvent, the volume ratio of aprotic polar solvent (I) to toluene is preferably 50 / 50 to 99 / 1, more preferably 60 / 40 to 99 / 1. When tetrahydrofuran is used as the other aprotic solvent, the volume ratio of aprotic polar solvent (I) to tetrahydrofuran is preferably 40 / 60 to 99 / 1, more preferably 50 / 50 to 99 / 1.

[0071] From the viewpoint of economy and ease of handling, the amount of nonionic superbase in the method for producing the solution or dispersion of the present invention is preferably 0.01 to 500 mol%, more preferably 0.1 to 200 mol%, and even more preferably 0.1 to 100 mol%, relative to the active hydrogen atoms of the sparingly soluble polymer. In this specification, "amount of B relative to A (mol%)" means "100 × amount of B (mol) / amount of A (mol)".

[0072] In this specification, "active hydrogen atoms in a sparingly soluble polymer" refers to the following equilibrium reaction at 25°C used to calculate the pKa of a sparingly soluble polymer: HP + sol ⇔ P － +Hsol ＋ In the formula (wherein HP represents a sparingly soluble polymer, H represents a hydrogen atom, and sol represents the solvent (acetonitrile)), it refers to the hydrogen atom abstracted as a proton (i.e., the H on the left side in the equilibrium reaction described above).

[0073] Specifically, "active hydrogen atoms in cellulose" refer to the hydrogen atoms in the hydroxyl groups (-OH) of cellulose. "Active hydrogen atoms in starch" refer to the hydrogen atoms in the hydroxyl groups (-OH) of starch. "Active hydrogen atoms in chitin" refer to the hydrogen atoms in the hydroxyl groups (-OH) and amide bonds (-CO-NH-) of chitin. "Active hydrogen atoms in aromatic polyamides" refer to the hydrogen atoms in the amide bonds (-CO-NH-) of aromatic polyamides. "Active hydrogen atoms in proteins" refer to the hydrogen atoms in the amide bonds (-CO-NH-) of proteins. "Active hydrogen atoms in polyfluorenes" refer to the hydrogen atoms at the benzyl position of polyfluorenes.

[0074] From the viewpoint of economy and ease of handling, the amount of nonionic superbase in the method for producing the solution of the present invention is preferably 1 to 500 mol%, more preferably 5 to 200 mol%, and even more preferably 10 to 100 mol%, relative to the active hydrogen atoms of the sparingly soluble polymer.

[0075] From the viewpoint of economy and ease of handling, the amount of nonionic superbase in the method for producing the dispersion of the present invention is preferably 0.01 to 100 mol%, more preferably 0.1 to 50 mol%, and even more preferably 0.1 to 20 mol%, relative to the active hydrogen atoms of the sparingly soluble polymer.

[0076] From the viewpoint of economy and ease of handling, the amount of sparingly soluble polymer in the method for producing the solution or dispersion of the present invention is preferably 0.1 to 100 wt%, more preferably 1 to 40 wt%, and even more preferably 1 to 20 wt%, relative to the aprotic solvent. In this specification, "amount of B relative to A (wt%)" means "100 × amount of B (g) / amount of A (g)".

[0077] From the viewpoint of economy and ease of handling, the amount of poorly soluble polymer in the method for producing the solution of the present invention is preferably 0.1 to 40 wt%, more preferably 1 to 30 wt%, and even more preferably 3 to 20 wt%, relative to the aprotic solvent.

[0078] From the viewpoint of economy and ease of handling, the amount of poorly soluble polymer in the method for producing the dispersion of the present invention is preferably 0.1 to 100 wt%, more preferably 1 to 40 wt%, and even more preferably 1 to 20 wt%, relative to the aprotic solvent.

[0079] To effectively dissolve or disperse the poorly soluble polymer, the temperature at which the poorly soluble polymer, the nonionic superbase, and the aprotic solvent are mixed, and the temperature at which the resulting suspension is stirred, are preferably 0 to 120°C, more preferably 20 to 80°C, and even more preferably 20 to 60°C.

[0080] To effectively dissolve or disperse the poorly soluble polymer, the stirring time of the suspension obtained by mixing the poorly soluble polymer, a nonionic superbase, and an aprotic solvent is preferably 1 minute to 120 hours, more preferably 1 minute to 48 hours, and even more preferably 1 minute to 24 hours.

[0081] <Solution or dispersion of poorly soluble polymers> The present invention provides a solution or dispersion containing a poorly soluble polymer (excluding cellulose in the form of cellulose carbonate anion), wherein the solution or dispersion comprises the poorly soluble polymer, a nonionic superbase, and an aprotic solvent, the pKa of the poorly soluble polymer being 50 or less under measurement conditions of a temperature of 25°C and the solvent being acetonitrile, the molecular weight of the nonionic superbase being 150 to 4,000, and the nonionic superbase having a branched structure and / or a cyclic structure.

[0082] The description of the poorly soluble polymer, nonionic superbase, and aprotic solvent in the solution or dispersion of the present invention is the same as the description in the <Method for Producing a Solution or Dispersion of a Poorly Soluble Polymer> described above.

[0083] <Method for Producing Cellulose Nanofibers> The present invention provides a method for producing cellulose nanofibers, the method comprising: mixing cellulose, a nonionic superbase, and an aprotic solvent under an inert gas atmosphere or an atmospheric atmosphere to obtain a solution or dispersion (preferably a solution) of cellulose; and mixing the solution or dispersion (preferably a solution) with water to obtain the cellulose nanofibers, wherein the molecular weight of the nonionic superbase is 150 to 4,000, and the nonionic superbase has a branched structure and / or a cyclic structure.

[0084] Unless otherwise specified, the descriptions of the nonionic superbase, aprotic solvent, and inert gas atmosphere or air atmosphere in the method for producing cellulose nanofibers of the present invention are the same as those described in the above-mentioned method for producing a solution or dispersion of a poorly soluble polymer.

[0085] In the method for producing cellulose nanofibers of the present invention, the aprotonate solvent comprises aprotonate solvent (I) (i.e., at least one selected from the group consisting of dimethyl sulfoxide, pyridine, 2-methylpyridine, 1-methylimidazole, and N,N-dimethylacetamide), and is more preferably aprotonate solvent (I). In the method for producing cellulose nanofibers of the present invention, the aprotonate solvent (I) is preferably dimethyl sulfoxide.

[0086] From the viewpoint of economy and ease of handling, the amount of nonionic superbase in the method for producing cellulose nanofibers of the present invention is preferably 0.01 to 100 mol%, more preferably 0.1 to 50 mol%, and even more preferably 0.1 to 20 mol%, relative to the active hydrogen atoms of cellulose (i.e., hydrogen atoms in the hydroxyl groups (-OH) of cellulose).

[0087] From the viewpoint of production efficiency, the amount of cellulose in the method for producing cellulose nanofibers of the present invention is preferably 0.1 to 100 wt%, more preferably 1 to 40 wt%, and even more preferably 1 to 20 wt%, relative to the aprotic solvent.

[0088] From the viewpoint of production efficiency, the temperature when mixing cellulose, nonionic superbase, and aprotic solvent, and the temperature when stirring the resulting suspension, are preferably 0 to 120°C, more preferably 20 to 80°C, and even more preferably 20 to 40°C.

[0089] From the viewpoint of production efficiency, the stirring time for the suspension obtained by mixing cellulose, a nonionic superbase, and an aprotic solvent is preferably 1 minute to 48 hours, more preferably 1 minute to 4 hours, and even more preferably 1 minute to 1 hour.

[0090] From the viewpoint of ease of handling, the amount of water in the method for producing cellulose nanofibers of the present invention is preferably 0.1 to 500 wt%, more preferably 1 to 200 wt%, and even more preferably 5 to 100 wt%, relative to the amount of cellulose used. Water may be mixed with the cellulose solution or dispersion as a mixed solvent with another solvent (e.g., methanol).

[0091] Cellulose nanofibers are obtained by mixing the aforementioned solution or dispersion with water. There are no particular limitations on the method of mixing, and it can be carried out by known means. For example, the mixing can be performed by spin-casting the solution or dispersion onto a support (e.g., highly oriented pyrolysis graphite) and washing it with water or a water-containing mixed solvent (e.g., water and methanol).

[0092] <Method for dissolving the surface of a poorly soluble polymer> The present invention provides a method for dissolving the surface of a poorly soluble polymer, the method comprising contacting the surface of the poorly soluble polymer with a solution containing a nonionic superbase and an aprotic solvent to dissolve the surface of the poorly soluble polymer, the pKa of the poorly soluble polymer being 50 or less under measurement conditions of a temperature of 25°C and the solvent being acetonitrile, the molecular weight of the nonionic superbase being 150 to 4,000, and the nonionic superbase having a branched structure and / or a cyclic structure.

[0093] Unless otherwise specified, the descriptions of nonionic superbases and aprotic solvents in the method for dissolving the surface of the sparingly soluble polymer of the present invention are the same as those described in the above-mentioned <Method for producing a solution or dispersion of a sparingly soluble polymer>.

[0094] In the method for dissolving the surface of a poorly soluble polymer of the present invention, the aprotonate solvent comprises aprotonate solvent (I) (i.e., at least one selected from the group consisting of dimethyl sulfoxide, pyridine, 2-methylpyridine, 1-methylimidazole, and N,N-dimethylacetamide), and is more preferably aprotonate solvent (I). In the method for dissolving the surface of a poorly soluble polymer of the present invention, the aprotonate solvent (I) is preferably dimethyl sulfoxide.

[0095] From the standpoint of practical availability and high industrial and academic demand, the poorly soluble polymer is preferably at least one selected from the group consisting of cellulose, starch, chitin, aromatic polyamides, proteins, and polyfluorene, and more preferably aromatic polyamides. The aromatic polyamide may be either a meta-aramid or a para-aramid.

[0096] From the viewpoint of economy and ease of handling, the concentration of the nonionic superbase in the solution is preferably 0.01 to 5 M, more preferably 0.1 to 2 M, and even more preferably 0.2 to 1 M.

[0097] Contact between the surface of a sparingly soluble polymer and a solution containing a nonionic superbase and an aprotic solvent may be carried out under either an inert gas atmosphere or an air atmosphere. The inert gas is preferably nitrogen gas. For convenience, the contact is preferably carried out under an air atmosphere.

[0098] To effectively dissolve the surface of a poorly soluble polymer, the temperature at which the surface of the poorly soluble polymer is brought into contact with a solution containing a nonionic superbase and an aprotic solvent is preferably 0 to 120°C, more preferably 20 to 80°C, and even more preferably 20 to 40°C.

[0099] <Method for bonding poorly soluble polymers> The present invention provides a method for bonding two poorly soluble polymers to each other, the method comprising contacting one surface of the poorly soluble polymer with a solution containing a nonionic superbase and an aprotic solvent, and contacting the one surface of the poorly soluble polymer that has been in contact with the solution with the other surface of the poorly soluble polymer, wherein the pKa of the poorly soluble polymer is 50 or less under measurement conditions of a temperature of 25°C and the solvent is acetonitrile, the molecular weight of the nonionic superbase is 150 to 4,000, and the nonionic superbase has a branched structure and / or a cyclic structure.

[0100] Unless otherwise specified, the descriptions of nonionic superbases and aprotic solvents in the adhesive method for poorly soluble polymers of the present invention are the same as those described in the above-mentioned <Method for producing a solution or dispersion of poorly soluble polymers>.

[0101] In the present invention's method for bonding poorly soluble polymers, the aprotonate solvent comprises aprotonate solvent (I) (i.e., at least one selected from the group consisting of dimethyl sulfoxide, pyridine, 2-methylpyridine, 1-methylimidazole, and N,N-dimethylacetamide), and is more preferably aprotonate solvent (I). In the method for bonding poorly soluble polymers, the aprotonate solvent (I) is preferably dimethyl sulfoxide.

[0102] The two poorly soluble polymers may be the same or different, but preferably they are the same. From the viewpoint of practical availability and high industrial and academic demand, the poorly soluble polymer is preferably at least one selected from the group consisting of cellulose, starch, chitin, aromatic polyamides, proteins, and polyfluorene, and more preferably an aromatic polyamide. The aromatic polyamide may be either a meta-aramid or a para-aramid.

[0103] From the viewpoint of economy and ease of handling, the concentration of the nonionic superbase in the solution is preferably 0.01 to 5 M, more preferably 0.1 to 2 M, and even more preferably 0.2 to 1 M.

[0104] Contact between one surface of a sparingly soluble polymer and a solution containing a nonionic superbase and an aprotic solvent may be carried out under either an inert gas atmosphere or an air atmosphere. The inert gas is preferably nitrogen gas. For convenience, the contact is preferably carried out under an air atmosphere.

[0105] To ensure good adhesion of poorly soluble polymers, the temperature at which one surface of the poorly soluble polymer is brought into contact with a solution containing a nonionic superbase and an aprotic solvent is preferably 0 to 120°C, more preferably 20 to 80°C, and even more preferably 20 to 40°C.

[0106] The method for bonding sparingly soluble polymers involves contacting one surface of a sparingly soluble polymer with a solution containing a nonionic superbase and an aprotic solvent, and then bringing the other surface of the sparingly soluble polymer into contact with each other to bond them together. The other surface of the sparingly soluble polymer may also be contacted with a solution containing a nonionic superbase and an aprotic solvent. In other words, in the bonding method for sparingly soluble polymers of the present invention, both surfaces of the sparingly soluble polymer may be contacted with a solution containing a nonionic superbase and an aprotic solvent, and then the two surfaces of the sparingly soluble polymer that have been contacted with the solution may be brought into contact with each other to bond them together.

[0107] The contact between one surface of the sparingly soluble polymer that has been in contact with the aforementioned solution and the other surface of the sparingly soluble polymer may be carried out under either an inert gas atmosphere or an air atmosphere. Nitrogen gas is preferred as the inert gas. For convenience, the contact is preferably carried out under an air atmosphere.

[0108] In order to ensure good adhesion of the poorly soluble polymer, the temperature at which one surface of the poorly soluble polymer that has been in contact with the solution is brought into contact with the other surface of the poorly soluble polymer is preferably 0 to 120°C, more preferably 20 to 80°C, and even more preferably 20 to 40°C.

[0109] To ensure good adhesion, it is preferable to bring one surface of the poorly soluble polymer, which has been in contact with the solution, into contact with the other surface of the poorly soluble polymer, and then press them together. To ensure good adhesion, the pressure applied during pressing should be 1 cm. ２ The weight per sheet is 10 to 10,000 g, more preferably 100 to 1,000 g. To ensure good adhesion, the pressing time is preferably 1 to 100 minutes, more preferably 1 to 30 minutes. The pressing temperature is preferably 0 to 120°C, more preferably 20 to 80°C. After pressing, it is preferable to wash the poorly soluble polymer with water and methanol and then dry it.

[0110] The present invention will be described in more detail below with reference to examples, but the present invention is not limited by the following examples, and it is possible to implement it with appropriate modifications within the scope that is consistent with the spirit of the above and below, and all such modifications are included in the technical scope of the present invention.

[0111] In the following examples, the following were used as nonionic superbases or sparingly soluble polymers: (1) Nonionic superbases: Superbase (2): Sigma-Aldrich "tert-butylimino-tri(pyrrolidino)phosphorane"; (4) 2.0 M tetrahydrofuran solution of superbase (4): Sigma-Aldrich "1-tert-butyl-2,2,4,4,4-pentakis(dimethylamino)-2λ" ５ ,4λ ５ - 2.0 M tetrahydrofuran solution of catenagy (phosphazene) 0.8 M hexane solution of superbase (6): Sigma-Aldrich "1-tert-butyl-4,4,4-tris(dimethylamino)-2,2-bis[tris(dimethylamino)phosphoranylideneamino]-2λ ５ ,4λ ５ - 0.8 M hexane solution of catenagy (phosphazene) Superbase (11): "1,3-di-tert-butylimidazole-2-ylidene" manufactured by Tokyo Chemical Industry Co., Ltd. Superbase (12): "2,8,9-triisopropyl-2,5,8,9-tetraaza-1-phosphabicyclo[3.3.3]undecane" manufactured by Sigma-Aldrich

[0112] (2) Cellulose Sigma-Aldrich "Avicel PH-101 (registered trademark)" Nacalai Tesque "Cellulose (powder)"

[0113] (3) α-Chitin manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.

[0114] (4) Starch made from starch-based lacryites

[0115] (5) Aromatic polyamide metharamid: DuPont's "Nomex®" Paraaramid: DuPont's "Kevlar®"

[0116] (6) Polyfluorene Polyfluorene synthesized by the method described in Polymer Journal, 2009, 41, 327-331 was used in the following examples.

[0117] Example 1 (Dissolution of cellulose in pyridine, amount of cellulose relative to aprotic solvent: 20 wt%, amount of nonionic superbase relative to hydroxyl groups of cellulose: 50 mol%) Under a nitrogen atmosphere, a 0.8 M hexane solution of superbase (6) (750 μL, 0.6 mmol) was added to a vial, and the hexane was removed by distillation under reduced pressure. To the dry superbase (6), pyridine (330 μL) and Sigma-Aldrich's "Avicel PH-101®" (64.9 mg, amount of hydroxyl groups: 1.2 mmol) were added as cellulose, and the suspension was stirred at approximately 25°C for 30 minutes to obtain a cellulose solution that was visually clear.

[0118] Example 2 (Dissolution of cellulose in DMSO, amount of cellulose relative to aprotic solvent: 1 wt%, amount of nonionic superbase relative to hydroxyl groups of cellulose: 10 mol%) Under a nitrogen atmosphere, a 0.8 M hexane solution of superbase (6) (15 μL, 0.012 mmol) was added to a vial, and the hexane was removed by distillation under reduced pressure. To the dry superbase (6), DMSO (590 μL) and Nacalai Tesque's "Cellulose (powder)" (6.42 mg, amount of hydroxyl groups: 0.12 mmol) were added, and the suspension was stirred at approximately 25°C for 30 minutes to obtain a cellulose solution that was visually clear.

[0119] Example 3 (Dissolution of cellulose in DMSO, amount of cellulose relative to aprotic solvent: 1.4 wt%, amount of nonionic superbase relative to hydroxyl groups of cellulose: 50 mol%) Under a nitrogen atmosphere, a 0.8 M hexane solution of superbase (6) (75 μL, 0.06 mmol), DMSO (400 μL), and Nacalai Tesque's "Cellulose (powder)" (6.42 mg, amount of hydroxyl groups: 0.12 mmol) were added to a vial, and the suspension was stirred at approximately 25°C for 1 minute to obtain a cellulose solution that was visibly clear.

[0120] Example 4 (Dissolution of cellulose in pyridine, amount of cellulose relative to aprotic solvent: 1.1 wt%, amount of nonionic superbase relative to hydroxyl groups of cellulose: 200 mol%) Under a nitrogen atmosphere, a 0.8 M hexane solution of superbase (6) (300 μL, 0.06 mmol), DMSO (400 μL), and Nacalai Tesque's "Cellulose (powder)" (6.55 mg, amount of hydroxyl groups: 0.12 mmol) were added to a vial, and the suspension was stirred at approximately 25°C for 10 minutes to obtain a cellulose solution that was visually clear.

[0121] Example 5 (Dissolution of cellulose in DMA, amount of cellulose relative to aprotic solvent: 1 wt%, amount of nonionic superbase relative to hydroxyl groups of cellulose: 50 mol%) Under a nitrogen atmosphere, a 0.8 M hexane solution of superbase (6) (75 μL, 0.06 mmol) was added to a vial, and the hexane was removed by distillation under reduced pressure. To the dry superbase (6), DMA (640 μL) and Nacalai Tesque's "Cellulose (powder)" (6.48 mg, amount of hydroxyl groups: 0.12 mmol) were added, and the suspension was stirred at approximately 25°C for 60 minutes to obtain a cellulose solution that was visually clear.

[0122] Example 6 (Dissolution of cellulose in 2-methylpyridine, amount of cellulose relative to aprotic solvent: 1 wt%, amount of nonionic superbase relative to hydroxyl groups of cellulose: 50 mol%) Under a nitrogen atmosphere, a 0.8 M hexane solution of superbase (6) (75 μL, 0.06 mmol) was added to a vial, and the hexane was removed by distillation under reduced pressure. 2-methylpyridine (680 μL) and Nacalai Tesque's "Cellulose (powder)" (6.49 mg, amount of hydroxyl groups: 0.12 mmol) were added to the dry superbase (6), and the suspension was stirred at approximately 25°C for 8 hours to obtain a cellulose solution that was visually clear.

[0123] Example 7 (Dissolution of cellulose in 1-methylimidazole, amount of cellulose relative to aprotic solvent: 1 wt%, amount of nonionic superbase relative to hydroxyl groups of cellulose: 50 mol%) Under a nitrogen atmosphere, a 0.8 M hexane solution of superbase (6) (75 μL, 0.06 mmol) was added to a vial, and the hexane was removed by distillation under reduced pressure. To the dry superbase (6), 1-methylimidazole (620 μL) and Nacalai Tesque's "Cellulose (powder)" (6.47 mg, amount of hydroxyl groups: 0.12 mmol) were added, and the suspension was stirred at approximately 25°C for 10 minutes to obtain a cellulose solution that was visually clear.

[0124] Example 8 (Dissolution of cellulose in a mixed solvent of DMSO and toluene, amount of cellulose relative to the aprotic solvent: 1 wt% or less, amount of nonionic superbase relative to the hydroxyl groups of cellulose: 50 mol%) Under a nitrogen atmosphere, a 0.8 M hexane solution of superbase (6) (75 μL, 0.06 mmol) was added to a vial, and the hexane was removed by distillation under reduced pressure. To the dry superbase (6), DMSO (590 μL), toluene (250 μL), and Sigma-Aldrich "Avicel PH-101®" (6.48 mg, amount of hydroxyl groups: 0.12 mmol) were added, and the suspension was stirred at approximately 25°C for 10 minutes to obtain a cellulose solution that was visually clear. When toluene (2.75 mL) was further added to the obtained solution, a visually clear solution (DMSO / toluene volume ratio: approximately 1 / 5) was obtained.

[0125] Example 9 (Dissolution of cellulose in DMSO, amount of cellulose relative to aprotic solvent: 1 wt%, amount of nonionic superbase relative to hydroxyl groups of cellulose: 100 mol%) Under a nitrogen atmosphere, a 2.0 M tetrahydrofuran solution of superbase (4) (120 μL, 0.24 mmol) was added to a vial, and the tetrahydrofuran was removed by distillation under reduced pressure. DMSO (1.18 mL) and Nacalai Tesque "Cellulose (powder)" (13.1 mg, amount of hydroxyl groups: 0.24 mmol) were added to the dry superbase (4), and the suspension was stirred at 60°C for 2 hours to obtain a cellulose solution that was visually clear.

[0126] Example 10 (Dissolution of absorbent cotton in pyridine, amount of cellulose relative to the aprotic solvent: 1 wt%, amount of nonionic superbase relative to the hydroxyl groups of cellulose when the absorbent cotton is considered to be entirely cellulose: 50 mol%) Under a nitrogen atmosphere, a 0.8 M hexane solution of superbase (6) (75 μL, 0.06 mmol) was added to a vial, and the hexane was removed by distillation under reduced pressure. Pyridine (660 μL) and absorbent cotton (6.43 mg, amount of hydroxyl groups when the absorbent cotton is considered to be entirely cellulose: 0.12 mmol) were added to the dry superbase (6), and the suspension was stirred at approximately 25°C for 15 minutes to obtain a visually clear solution.

[0127] Example 11 (Dissolution of α-chitin in pyridine, amount of α-chitin relative to aprotic solvent: 1 wt%, amount of nonionic superbase relative to hydroxyl groups of α-chitin: 100 mol%) Under a nitrogen atmosphere, a 0.8 M hexane solution of superbase (6) (150 μL, 0.12 mmol) was added to a vial, and the hexane was removed by distillation under reduced pressure. Pyridine (830 μL) and α-chitin (8.19 mg, total amount of hydroxyl groups and amide bonds: 0.12 mmol) were added to the dry superbase (6), and the suspension was stirred at approximately 25°C for 5 minutes to obtain a visually clear α-chitin solution.

[0128] Example 12 (Dissolution of cellulose in DMSO, amount of cellulose relative to aprotic solvent: 0.2 wt%, amount of nonionic superbase relative to hydroxyl groups of cellulose: 2.5 or 5 mol%) Under a nitrogen atmosphere, 3.75 μL (0.003 mmol) or 7.50 μL (0.006 mmol) of a 0.8 M hexane solution of superbase (6) was added to a vial, to which DMSO (2.95 mL) and Sigma-Aldrich "Avicel PH-101®" (6.49 mg, amount of hydroxyl groups: 0.12 mmol) were added as cellulose, respectively. The suspension was stirred at approximately 25°C for 24 hours to prepare a dispersion in which the amount of superbase (6) relative to the hydroxyl groups of cellulose was 2.5 mol%, or a clear cellulose solution in which the amount of superbase (6) relative to the hydroxyl groups of cellulose was 5.0 mol%.

[0129] For comparison with the cellulose dispersion and cellulose solution described above, a mixture of DMSO and cellulose was prepared using the same procedure as above, except that superbase (6) was not used. This mixture was not transparent, and when it was allowed to stand at 25°C, the cellulose precipitated in less than 5 minutes. Thus, without using superbase (6), a cellulose dispersion or solution could not be obtained.

[0130] A cellulose solution with a superbase (6) content of 5.0 mol% relative to the hydroxyl groups of cellulose was visually transparent, indicating that the cellulose had dissolved in the solvent. Furthermore, dynamic light scattering measurements were performed on the above cellulose dispersion and cellulose solution at 25°C. The results are shown in Figure 1. In Figure 1, the horizontal axis represents the hydrodynamic diameter (nm), and the vertical axis represents the number of particles. The peak tops for the dispersion with a superbase (6) content of 2.5 mol% and the solution with a superbase (6) content of 5.0 mol% were 955 nm and 21.0 nm, respectively, confirming that the particle size of cellulose in the solution decreased as the superbase (6) content increased.

[0131] Example 13 (Production of Cellulose Nanofibers, Amount of Cellulose relative to Aprotic Solvent: 0.2 wt%, Amount of Nonionic Superbase relative to Hydroxyl Groups in Cellulose: 7.5 mol%) Under a nitrogen atmosphere, a 0.8 M hexane solution of superbase (6) (11.3 μL, 0.009 mmol), DMSO (2.95 mL), and Sigma-Aldrich "Avicel PH-101®" (6.49 mg, hydroxyl group amount: 0.12 mmol) as cellulose were added to a vial, and the suspension was stirred at approximately 25°C for 24 hours to prepare a visually clear solution. The obtained solution was spin-cast onto highly oriented pyrolysis graphite (HOPG), then washed with water and methanol, and the washed HOPG was dried at room temperature under reduced pressure. An atomic force microscope image of the dried HOPG surface was taken. The image is shown in Figure 2. As shown in Figure 2, it was observed that cellulose nanofibers with a thickness of approximately 10 to 50 nm were formed on the HOPG surface.

[0132] Example 14 (Dissolution of cellulose in pyridine and regeneration of cellulose, amount of cellulose relative to aprotic solvent: 1 wt%, amount of nonionic superbase relative to hydroxyl groups of cellulose: 50 mol%) Under a nitrogen atmosphere, a 0.8 M hexane solution of superbase (6) (75 μL, 0.06 mmol) was added to a vial, and the hexane was removed by distillation under reduced pressure. To the dry superbase (6), pyridine (660 μL) and Nacalai Tesque's "Cellulose (powder)" (6.52 mg, amount of hydroxyl groups: 0.12 mmol) were added as cellulose, and the suspension was stirred at approximately 25°C for 30 minutes to obtain a cellulose solution that was visually clear.

[0133] The precipitate obtained by adding the above solution to 20 mL of water was collected, washed with methanol, and then vacuum-dried overnight to obtain regenerated cellulose as a white film-like solid (5.86 mg, yield: 91%).

[0134] Example 15 (Dissolution of Cellulose in Pyridine and Subsequent Esterification Reaction) Under a nitrogen atmosphere, a 0.8 M hexane solution of superbase (6) (180 μL, 0.144 mmol) was added to a vial, and the hexane was removed by distillation under reduced pressure. To the dry superbase (6), pyridine (660 μL) and Nacalai Tesque "Cellulose (Powder)" (6.54 mg, hydroxyl group content: 0.12 mmol) were added, and the suspension was stirred at approximately 25°C for 2 hours to prepare a cellulose solution that was visually clear.

[0135] To the obtained solution, 4-toluoyl chloride (19.0 μL, 0.144 mmol) was added, and the resulting reaction solution was stirred at approximately 25°C for 2 hours. Then, the reaction solution was added to 20 mL of citric acid solution (citric acid concentration: 0.025 M, solvent: mixed solvent of water and methanol (volume ratio: 1 / 1)), and the precipitate obtained was collected, washed with methanol, and then vacuum-dried overnight to obtain a white solid product (ester of cellulose and 4-toluoyl chloride) (14.2 mg, yield: 69%, degree of substitution (= "average number of functional groups introduced per glucose unit in cellulose", the same applies below): 2.1).

[0136] Example 16 (Dissolution of Cellulose in Pyridine and Subsequent Esterification Reaction) Under a nitrogen atmosphere, a 0.8 M hexane solution of superbase (6) (180 μL, 0.144 mmol) was added to a vial, and the hexane was removed by distillation under reduced pressure. To the dry superbase (6), pyridine (660 μL) and Nacalai Tesque's "Cellulose (Powder)" (6.45 mg, hydroxyl group content: 0.12 mmol) were added, and the suspension was stirred at approximately 25°C for 2 hours to prepare a cellulose solution that was visually clear.

[0137] To the obtained solution, octanoic anhydride (42.8 μL, 0.144 mmol) was added, and the resulting reaction solution was stirred at approximately 25°C for 2 hours. Then, the reaction solution was added to 20 mL of citric acid solution (citric acid concentration: 0.025 M, solvent: mixed solvent of water and methanol (volume ratio: 1 / 1)), and the precipitate obtained was collected, washed with methanol, and then vacuum-dried overnight to obtain a white solid product (ester of cellulose and octanoic anhydride) (10.5 mg, yield: 49%, degree of substitution: 3.0).

[0138] Example 17 (Dissolution of Cellulose in Pyridine and Subsequent Silylation Reaction) Under a nitrogen atmosphere, a 0.8 M hexane solution of superbase (6) (180 μL, 0.144 mmol) was added to a vial, and the hexane was removed by distillation under reduced pressure. To the dry superbase (6), pyridine (660 μL) and Nacalai Tesque's "Cellulose (Powder)" (6.58 mg, hydroxyl group content: 0.12 mmol) were added, and the suspension was stirred at approximately 25°C for 2 hours to prepare a cellulose solution that was visually clear.

[0139] Triisopropylsilyl chloride (30.2 μL, 0.144 mmol) was added to the obtained solution, and the resulting reaction solution was stirred at approximately 25°C for 2 hours. Then, the reaction solution was added to 20 mL of citric acid solution (citric acid concentration: 0.025 M, solvent: mixed solvent of water and methanol (volume ratio: 1 / 1)), and the precipitate obtained was collected, washed with methanol, and then vacuum-dried overnight to obtain a white solid product (cellulose in which some hydrogen atoms of hydroxyl groups were replaced with silyl groups) (14.4 mg, yield: 57%, degree of substitution: 0.5).

[0140] Example 18 (Dissolution of cellulose in pyridine and subsequent alkylation reaction) Under a nitrogen atmosphere, a 0.8 M hexane solution of superbase (6) (180 μL, 0.144 mmol) was added to a vial, and the hexane was removed by distillation under reduced pressure. To the dry superbase (6), pyridine (660 μL) and Nacalai Tesque "Cellulose (powder)" (6.58 mg, 0.12 mmol) were added, and the suspension was stirred at approximately 25°C for 2 hours to prepare a cellulose solution that was visually clear.

[0141] After adding p-tert butylbenzyl chloride (26.0 μL, 0.144 mmol) to the obtained solution, the reaction solution was stirred at approximately 25°C for 2 hours. Then, the reaction solution was added to 20 mL of citric acid solution (citric acid concentration: 0.025 M, solvent: mixed solvent of water and methanol (volume ratio: 1 / 1)), and the precipitate obtained was collected, washed with diethyl ether, and then vacuum-dried overnight to obtain a white solid product (cellulose in which some hydrogen atoms of hydroxyl groups were replaced with alkyl groups (substituted benzyl groups)) (12.6 mg, yield: 53%, degree of substitution: 1.2).

[0142] Example 19 (Dissolution of cellulose in pyridine and subsequent arylation reaction) Under a nitrogen atmosphere, a 0.8 M hexane solution of superbase (6) (180 μL, 0.144 mmol) was added to a vial, and the hexane was removed by distillation under reduced pressure. To the dry superbase (6), pyridine (660 μL) and Nacalai Tesque "Cellulose (powder)" (6.49 mg, hydroxyl group amount: 0.12 mmol) were added, and the suspension was stirred at approximately 25°C for 2 hours to prepare a cellulose solution that was visually clear.

[0143] 4-fluoronitrobenzene (15.3 μL, 0.144 mmol) was added to the obtained solution, and the resulting reaction solution was stirred at approximately 25°C for 2 hours. Then, the reaction solution was added to 20 mL of citric acid solution (citric acid concentration: 0.025 M, solvent: mixed solvent of ethanol and hexane (volume ratio: 1 / 1)), and the precipitate obtained was collected, washed with diethyl ether, and then vacuum-dried overnight to obtain a brown solid product (cellulose in which all hydrogen atoms of hydroxyl groups are replaced by aryl groups (substituted phenyl groups)) (20.9 mg, yield: 100%, degree of substitution: 3.0).

[0144] Example 20 (Dissolution of cellulose in pyridine, and subsequent thiocarbamate reaction) Under a nitrogen atmosphere, a 0.8 M hexane solution of superbase (6) (180 μL, 0.144 mmol) was added to a vial, and the hexane was removed by distillation under reduced pressure. To the dry superbase (6), pyridine (660 μL) and Nacalai Tesque's "Cellulose (powder)" (6.49 mg, hydroxyl group amount: 0.12 mmol) were added, and the suspension was stirred at approximately 25°C for 2 hours to prepare a cellulose solution that was visually clear.

[0145] After adding 1-adamantyl isothiocyanate (28.0 mg, 0.144 mmol) to the obtained solution, the reaction solution was stirred at approximately 25°C for 2 hours. Then, the reaction solution was added to 20 mL of citric acid solution (citric acid concentration: 0.025 M, solvent: mixed solvent of ethanol and hexane (volume ratio of ethanol / hexane: 1 / 2)), and the precipitate obtained was collected, washed with diethyl ether, and then vacuum-dried overnight to obtain a white solid product (cellulose in which some hydrogen atoms of hydroxyl groups were replaced with thiocarbamoyl groups) (17.6 mg, yield: 59%, degree of substitution: 1.7).

[0146] Example 21 (Dissolution of cellulose in pyridine and subsequent urethane reaction) Under a nitrogen atmosphere, a 0.8 M hexane solution of superbase (6) (180 μL, 0.144 mmol) was added to a vial, and the hexane was removed by distillation under reduced pressure. To the dry superbase (6), pyridine (660 μL) and Nacalai Tesque's "Cellulose (powder)" (6.49 mg, hydroxyl group content: 0.12 mmol) were added, and the suspension was stirred at approximately 25°C for 2 hours to prepare a cellulose solution that was visually clear.

[0147] After adding dodecyl isocyanate (35.0 μL, 0.144 mmol) to the obtained solution, the reaction solution was stirred at approximately 25°C for 2 hours. Subsequently, the reaction solution was added to 20 mL of ethanol solution of acetic acid (acetic acid concentration: 0.15 M), and the precipitate obtained was collected. After washing with ethanol, the precipitate was vacuum-dried overnight to obtain a white solid product (cellulose with some hydroxyl groups urethane-treated) (8.43 mg, yield: 27%, degree of substitution: 0.5).

[0148] Example 22 (Dissolution of cellulose in pyridine and subsequent sulfonylation reaction) Under a nitrogen atmosphere, a 0.8 M hexane solution of superbase (6) (180 μL, 0.144 mmol) was added to a vial, and the hexane was removed by distillation under reduced pressure. To the dry superbase (6), pyridine (660 μL) and Nacalai Tesque "Cellulose (powder)" (6.49 mg, hydroxyl group amount: 0.12 mmol) were added, and the suspension was stirred at approximately 25°C for 2 hours to prepare a cellulose solution that was visually clear.

[0149] Tosyl chloride (27.5 mg, 0.144 mmol) was added to the obtained solution, and the resulting reaction solution was stirred at approximately 25°C for 2 hours. Then, the reaction solution was added to 20 mL of citric acid solution (citric acid concentration: 0.025 M, solvent: mixed solvent of ethanol and hexane (volume ratio of ethanol / hexane: 1 / 2)), and the precipitate obtained was collected, washed with diethyl ether, and then vacuum-dried overnight to obtain a light brown solid product (cellulose with some hydroxyl groups sulfonylated) (10.3 mg, yield: 41%, degree of substitution: 1.2).

[0150] Example 23 (Dissolution of cellulose in pyridine, and subsequent ring-opening polymerization of caprolactone using hydroxyl groups on cellulose as initiators) Under a nitrogen atmosphere, a 0.8 M hexane solution of superbase (6) (75 μL, 0.06 mmol) was added to a vial, and the hexane was removed by distillation under reduced pressure. To the dry superbase (6), pyridine (660 μL) and Nacalai Tesque's "Cellulose (powder)" (6.48 mg, hydroxyl group amount: 0.12 mmol) were added, and the suspension was stirred at approximately 25°C for 2 hours to prepare a cellulose solution that was visually clear.

[0151] After adding caprolactone (101 μL, 0.96 mmol) to the obtained solution, the reaction solution was stirred at approximately 25°C for 2 hours. Then, the reaction solution was added to 20 mL of an ethanol solution of acetic acid (acetic acid concentration: 0.15 M) to collect the precipitate, which was washed with ethanol and then vacuum-dried overnight to obtain a white solid product (cellulose with caprolactone attached to the hydroxyl groups) (28.3 mg, yield: 25%, degree of substitution (MS) (= "average number of caprolactones introduced per glucose unit in cellulose"): 7.3).

[0152] Example 24 (Dissolution of sawdust (pine-derived) in pyridine, amount of sawdust relative to aprotic solvent: 1 wt%, amount of nonionic superbase relative to hydroxyl groups in cellulose when sawdust is considered entirely as cellulose: 100 mol%) Under a nitrogen atmosphere, a 0.8 M hexane solution of superbase (6) (150 μL, 0.12 mmol) was added to a vial, and the hexane was removed by distillation under reduced pressure. Pyridine (660 μL) and sawdust (6.45 mg, amount of hydroxyl groups when sawdust is considered entirely as cellulose: 0.12 mmol) were added to the dry superbase (6), and the suspension was stirred at approximately 25°C for 30 minutes to obtain a visually clear solution.

[0153] Example 25 (Dissolution of rice bran in pyridine, amount of rice bran relative to aprotic solvent: 1 wt%, amount of nonionic superbase relative to hydroxyl groups in cellulose when rice bran is considered entirely as cellulose: 100 mol%) Under a nitrogen atmosphere, a 0.8 M hexane solution of superbase (6) (150 μL, 0.12 mmol) was added to a vial, and the hexane was removed by distillation under reduced pressure. Pyridine (660 μL) and rice bran (6.48 mg, amount of hydroxyl groups when rice bran is considered entirely as cellulose: 0.12 mmol) were added to the dry superbase (6), and the suspension was stirred at approximately 25°C for 30 minutes to obtain a visually clear solution.

[0154] Example 26 (Dissolution of starch in pyridine, amount of starch relative to aprotic solvent: 1 wt%, amount of nonionic superbase relative to hydroxyl groups of starch when all starch is considered amylose: 100 mol%) Under a nitrogen atmosphere, a 0.8 M hexane solution of superbase (6) (150 μL, 0.12 mmol) was added to a vial, and the hexane was removed by distillation under reduced pressure. Pyridine (660 μL) and starch (6.50 mg, amount of hydroxyl groups when all starch is considered amylose: 0.12 mmol) were added to the dry superbase (6), and the suspension was stirred at approximately 25°C for 1 minute to obtain a visually clear solution.

[0155] Example 27 (Dissolution of bagasse (sugarcane residue) in pyridine and regeneration of cellulose (amount of bagasse relative to aprotic solvent: 1 wt%, amount of nonionic superbase relative to hydroxyl groups when bagasse is considered entirely as cellulose: 100 mol%)) Under a nitrogen atmosphere, a 0.8 M hexane solution of superbase (6) (150 μL, 0.12 mmol) was added to a vial, and the hexane was removed by distillation under reduced pressure. Pyridine (660 μL) and bagasse (6.48 mg, amount of hydroxyl groups when bagasse is considered entirely as cellulose: 0.12 mmol) were added to the dry superbase (6), and the suspension was stirred at approximately 25°C for 30 minutes to obtain a visually clear solution.

[0156] The precipitate obtained by adding the above solution to 20 mL of water was collected, washed with methanol, and then vacuum-dried overnight to obtain regenerated cellulose as a brown film-like solid (4.60 mg, yield: 71%).

[0157] Example 28 (Dissolution of meta-aramid in DMSO, amount of meta-aramid relative to aprotic solvent: 1 wt%, amount of nonionic superbase relative to amide bonds in meta-aramid: 50 mol%) Under a nitrogen atmosphere, a 0.8 M hexane solution of superbase (6) (25 μL, 0.02 mmol), DMSO (430 μL), and meta-aramid (4.76 mg, amount of amide bonds: 0.04 mmol) were added to a vial, and the suspension was stirred at 60°C for 4 hours to obtain a meta-aramid solution that was visibly clear.

[0158] Example 29 (Dissolution of para-aramid in DMSO, amount of para-aramid relative to aprotic solvent: 0.2 wt%, amount of nonionic superbase relative to amide bonds in para-aramid: 100 mol%) Under a nitrogen atmosphere, a 0.8 M hexane solution of superbase (6) (50 μL, 0.04 mmol) was added to a vial, and the hexane was removed by distillation under reduced pressure. DMSO (2.17 mL) and para-aramid (4.72 mg, amount of amide bonds: 0.04 mmol) were added to the dry superbase (6), and the suspension was stirred at approximately 25°C for 3 hours to obtain a visually clear para-aramid solution.

[0159] Example 30 (Dissolution of protein-containing wool in DMSO, amount of wool relative to aprotic solvent: 1 wt%, amount of nonionic superbase relative to amide bonds in the protein when the wool is considered entirely as polyglycine (protein): 100 mol%) Under a nitrogen atmosphere, a 0.8 M hexane solution of superbase (6) (50 μL, 0.04 mmol), DMSO (230 μL), and wool (2.22 mg, amount of amide bonds when the wool is considered entirely as polyglycine: 0.04 mmol) were added to a vial, and the suspension was stirred at 60°C for 1 day to obtain a visually clear solution.

[0160] Example 31 (Surface dissolution and adhesion of para-aramid fiber woven fabric) Under a nitrogen atmosphere, a 0.8 M hexane solution of superbase (6) (150 μL, 0.12 mmol) and DMSO (590 μL) were added to a vial, and the mixture was stirred to prepare a solution (concentration of nonionic superbase: 0.16 M). Of the obtained solution, 100 μL of the solution was uniformly applied to a 1 cm square tip of a para-aramid fiber woven fabric piece (width 10 mm × length 30 mm × thickness 0.5 mm), and its surface was dissolved.

[0161] A piece of woven fabric coated with the aforementioned solution was placed over a 1 cm square section of the tip of another piece of woven fabric of the same size (10 mm wide x 30 mm long x 0.5 mm thick), and a 500 g weight was placed on top to press them together for 20 minutes. After pressing, the woven fabric pieces were washed with water and methanol and dried. When the upper end of the bonded woven fabric pieces was fixed and a 5 g weight was hung from the lower end, the weight could be suspended without the bonded surface peeling off. When the same procedure was performed using DMSO without the superbase (6) instead of the aforementioned solution, the woven fabric pieces could not be bonded together.

[0162] Example 32 (Dissolution of polyfluorene in DMSO, amount of polyfluorene relative to aprotic solvent: 1 wt%, amount of nonionic superbase relative to the benzyl hydrogen atom of polyfluorene: 50 mol%) Under a nitrogen atmosphere, a 0.8 M hexane solution of superbase (6) (25 μL, 0.02 mmol) was added to a vial, and the hexane was removed by distillation under reduced pressure. DMSO (300 μL) and polyfluorene (3.15 mg, amount of hydrogen atom at the benzyl position: 0.04 mmol) were added to the dry superbase (6), and the suspension was stirred at approximately 25°C for 1 minute to obtain a visually clear polyfluorene solution.

[0163] Example 33 (Dissolution of polyfluorene in pyridine, amount of polyfluorene relative to aprotic solvent: 1 wt%, amount of nonionic superbase relative to the benzyl hydrogen atom of polyfluorene: 50 mol%) Under a nitrogen atmosphere, a 0.8 M hexane solution of superbase (6) (25 μL, 0.02 mmol) was added to a vial, and the hexane was removed by distillation under reduced pressure. Pyridine (340 μL) and polyfluorene (3.15 mg, amount of hydrogen atom at the benzyl position: 0.04 mmol) were added to the dry superbase (6), and the suspension was stirred at approximately 25°C for 10 seconds to obtain a visually clear polyfluorene solution.

[0164] Example 34 (Dissolution of cellulose in DMSO, amount of cellulose relative to aprotic solvent: 0.2 wt%, amount of nonionic superbase relative to hydroxyl groups of cellulose: 100 mol%) Under a nitrogen atmosphere, superbase (11) (21.9 mg, 0.12 mmol) was added to a vial, DMSO (2.94 mL) and Sigma-Aldrich's "Avicel PH-101®" (6.51 mg, amount of hydroxyl groups: 0.12 mmol) were added as cellulose, and the suspension was stirred at approximately 60°C for 24 hours to obtain a cellulose solution that was visually clear.

[0165] Example 35 (Dissolution of cellulose in DMSO, amount of cellulose relative to aprotic solvent: 0.2 wt%, amount of nonionic superbase relative to hydroxyl groups of cellulose: 100 mol%) Under a nitrogen atmosphere, superbase (12) (21.3 μL, 0.06 mmol) was added to a vial, DMSO (1.47 mL) and Sigma-Aldrich's "Avicel PH-101®" (3.26 mg, amount of hydroxyl groups: 0.06 mmol) were added as cellulose, and the suspension was stirred at approximately 60°C for 15 hours to obtain a cellulose solution that was visually clear.

[0166] Example 36 (Dissolution of cellulose in DMSO, amount of cellulose relative to aprotic solvent: 0.2 wt%, amount of nonionic superbase relative to hydroxyl groups of cellulose: 100 mol%) Under a nitrogen atmosphere, superbase (2) (18.3 μL, 0.06 mmol) was added to a vial, DMSO (1.47 mL) and Sigma-Aldrich's "Avicel PH-101®" (3.15 mg, amount of hydroxyl groups: 0.06 mmol) were added as cellulose, and the suspension was stirred at approximately 60°C for 24 hours to obtain a cellulose solution that was visually clear.

[0167] Example 37 (Production of Cellulose Nanofibers, Amount of Cellulose relative to Aprotic Solvent: 0.6 wt%, Amount of Nonionic Superbase relative to Hydroxyl Groups in Cellulose: 8.0 mol%) Under a nitrogen atmosphere, a 0.8 M hexane solution of superbase (6) (12.0 μL, 0.009 mmol) was added to a vial, and the hexane was removed by distillation under reduced pressure. Then, DMSO (1.00 mL) and absorbent cotton (6.52 mg, Amount of hydroxyl groups when the absorbent cotton is considered to be entirely cellulose: 0.12 mmol) were added, and the suspension was stirred at approximately 25°C for 4 hours to prepare a visually clear solution. The obtained solution was spin-cast onto highly oriented pyrolysis graphite (HOPG), then washed with water and methanol, and the washed HOPG was dried at room temperature under reduced pressure. An atomic force microscope image of the dried HOPG surface was taken. The image is shown in Figure 3. As shown in Figure 3, it was observed that cellulose nanofibers with a thickness of approximately 3 to 5 nm were formed on the HOPG surface.

[0168] According to the present invention, various poorly soluble polymers can be dissolved or dispersed without using carbon dioxide, which is an environmentally harmful substance, and as a result, the processing or handling of poorly soluble polymers becomes easier.

[0169] This application is based on Japanese Patent Application No. 2024-213180, which is entirely contained herein.

Claims

A method for producing a solution or dispersion containing a poorly soluble polymer, The method comprises mixing the poorly soluble polymer, a nonionic superbase, and an aprotic solvent under an inert gas atmosphere or an atmospheric atmosphere. The pKa of the aforementioned poorly soluble polymer is 50 or less under measurement conditions where the temperature is 25°C and the solvent is acetonitrile. The molecular weight of the aforementioned nonionic superbase is 150 to 4,000, and The nonionic superbase has a branched structure and / or a cyclic structure. method. 　 The method according to claim 1, wherein the amount of the nonionic superbase is 0.01 to 500 mol% with respect to the active hydrogen atoms of the sparingly soluble polymer. 　 The aforementioned nonionic superbase is a superbase represented by the following formula (1) to a superbase represented by the following formula (12): (In the formula, Me represents a methyl group, Et represents an ethyl group, and tBu represents a tert-butyl group.) The method according to claim 1 or 2, wherein at least one is selected from the group consisting of the following. 　 The method according to claim 1 or 2, wherein the poorly soluble polymer is at least one selected from the group consisting of cellulose, starch, chitin, aromatic polyamide, protein, and polyfluorene. 　 The method according to claim 1 or 2, wherein the aprotic solvent comprises at least one aprotic polar solvent selected from the group consisting of dimethyl sulfoxide, pyridine, 2-methylpyridine, 1-methylimidazole, and N,N-dimethylacetamide. 　 A solution or dispersion containing a poorly soluble polymer (excluding cellulose in the form of cellulose carbonate anion), The solution or dispersion comprises the sparingly soluble polymer, a nonionic superbase, and an aprotic solvent. The pKa of the aforementioned poorly soluble polymer is 50 or less under measurement conditions where the temperature is 25°C and the solvent is acetonitrile. The molecular weight of the aforementioned nonionic superbase is 150 to 4,000, and The nonionic superbase has a branched structure and / or a cyclic structure. A solution or dispersion. 　 A method for producing cellulose nanofibers, The aforementioned method, Mixing cellulose, a nonionic superbase, and an aprotic solvent under an inert gas atmosphere or air atmosphere to obtain a cellulose solution or dispersion, and The cellulose nanofibers are obtained by mixing the aforementioned solution or dispersion with water. Includes, The molecular weight of the nonionic superbase is 150 to 4,000, and The nonionic superbase has a branched structure and / or a cyclic structure. method. 　 A method for dissolving the surface of a poorly soluble polymer, The method includes contacting the surface of the poorly soluble polymer with a solution containing a nonionic superbase and an aprotic solvent to dissolve the surface of the poorly soluble polymer. The pKa of the aforementioned poorly soluble polymer is 50 or less under measurement conditions where the temperature is 25°C and the solvent is acetonitrile. The molecular weight of the aforementioned nonionic superbase is 150 to 4,000, and The nonionic superbase has a branched structure and / or a cyclic structure. method. 　 A method for bonding two poorly soluble polymers together, The aforementioned method, Contacting one surface of the poorly soluble polymer with a solution containing a nonionic superbase and an aprotic solvent, and Bringing one surface of the poorly soluble polymer that has been in contact with the solution into contact with the other surface of the poorly soluble polymer. Includes, The pKa of the aforementioned poorly soluble polymer is 50 or less under measurement conditions where the temperature is 25°C and the solvent is acetonitrile. The molecular weight of the aforementioned nonionic superbase is 150 to 4,000, and The nonionic superbase has a branched structure and / or a cyclic structure. method.

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